core/num/uint_macros.rs
1macro_rules! uint_impl {
2 (
3 Self = $SelfT:ty,
4 ActualT = $ActualT:ident,
5 SignedT = $SignedT:ident,
6
7 // These are all for use *only* in doc comments.
8 // As such, they're all passed as literals -- passing them as a string
9 // literal is fine if they need to be multiple code tokens.
10 // In non-comments, use the associated constants rather than these.
11 BITS = $BITS:literal,
12 BITS_MINUS_ONE = $BITS_MINUS_ONE:literal,
13 MAX = $MaxV:literal,
14 rot = $rot:literal,
15 rot_op = $rot_op:literal,
16 rot_result = $rot_result:literal,
17 fsh_op = $fsh_op:literal,
18 fshl_result = $fshl_result:literal,
19 fshr_result = $fshr_result:literal,
20 clmul_lhs = $clmul_lhs:literal,
21 clmul_rhs = $clmul_rhs:literal,
22 clmul_result = $clmul_result:literal,
23 swap_op = $swap_op:literal,
24 swapped = $swapped:literal,
25 reversed = $reversed:literal,
26 le_bytes = $le_bytes:literal,
27 be_bytes = $be_bytes:literal,
28 to_xe_bytes_doc = $to_xe_bytes_doc:expr,
29 from_xe_bytes_doc = $from_xe_bytes_doc:expr,
30 bound_condition = $bound_condition:literal,
31 ) => {
32 /// The smallest value that can be represented by this integer type.
33 ///
34 /// # Examples
35 ///
36 /// ```
37 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MIN, 0);")]
38 /// ```
39 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
40 pub const MIN: Self = 0;
41
42 /// The largest value that can be represented by this integer type
43 #[doc = concat!("(2<sup>", $BITS, "</sup> − 1", $bound_condition, ").")]
44 ///
45 /// # Examples
46 ///
47 /// ```
48 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX, ", stringify!($MaxV), ");")]
49 /// ```
50 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
51 pub const MAX: Self = !0;
52
53 /// The size of this integer type in bits.
54 ///
55 /// # Examples
56 ///
57 /// ```
58 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::BITS, ", stringify!($BITS), ");")]
59 /// ```
60 #[stable(feature = "int_bits_const", since = "1.53.0")]
61 pub const BITS: u32 = Self::MAX.count_ones();
62
63 /// Returns the number of ones in the binary representation of `self`.
64 ///
65 /// # Examples
66 ///
67 /// ```
68 #[doc = concat!("let n = 0b01001100", stringify!($SelfT), ";")]
69 /// assert_eq!(n.count_ones(), 3);
70 ///
71 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
72 #[doc = concat!("assert_eq!(max.count_ones(), ", stringify!($BITS), ");")]
73 ///
74 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
75 /// assert_eq!(zero.count_ones(), 0);
76 /// ```
77 #[stable(feature = "rust1", since = "1.0.0")]
78 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
79 #[doc(alias = "popcount")]
80 #[doc(alias = "popcnt")]
81 #[must_use = "this returns the result of the operation, \
82 without modifying the original"]
83 #[inline(always)]
84 pub const fn count_ones(self) -> u32 {
85 return intrinsics::ctpop(self);
86 }
87
88 /// Returns the number of zeros in the binary representation of `self`.
89 ///
90 /// # Examples
91 ///
92 /// ```
93 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
94 #[doc = concat!("assert_eq!(zero.count_zeros(), ", stringify!($BITS), ");")]
95 ///
96 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
97 /// assert_eq!(max.count_zeros(), 0);
98 /// ```
99 ///
100 /// This is heavily dependent on the width of the type, and thus
101 /// might give surprising results depending on type inference:
102 /// ```
103 /// # fn foo(_: u8) {}
104 /// # fn bar(_: u16) {}
105 /// let lucky = 7;
106 /// foo(lucky);
107 /// assert_eq!(lucky.count_zeros(), 5);
108 /// assert_eq!(lucky.count_ones(), 3);
109 ///
110 /// let lucky = 7;
111 /// bar(lucky);
112 /// assert_eq!(lucky.count_zeros(), 13);
113 /// assert_eq!(lucky.count_ones(), 3);
114 /// ```
115 /// You might want to use [`Self::count_ones`] instead, or emphasize
116 /// the type you're using in the call rather than method syntax:
117 /// ```
118 /// let small = 1;
119 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::count_zeros(small), ", stringify!($BITS_MINUS_ONE) ,");")]
120 /// ```
121 #[stable(feature = "rust1", since = "1.0.0")]
122 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
123 #[must_use = "this returns the result of the operation, \
124 without modifying the original"]
125 #[inline(always)]
126 pub const fn count_zeros(self) -> u32 {
127 (!self).count_ones()
128 }
129
130 /// Returns the number of leading zeros in the binary representation of `self`.
131 ///
132 /// Depending on what you're doing with the value, you might also be interested in the
133 /// [`ilog2`] function which returns a consistent number, even if the type widens.
134 ///
135 /// # Examples
136 ///
137 /// ```
138 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX >> 2;")]
139 /// assert_eq!(n.leading_zeros(), 2);
140 ///
141 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
142 #[doc = concat!("assert_eq!(zero.leading_zeros(), ", stringify!($BITS), ");")]
143 ///
144 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
145 /// assert_eq!(max.leading_zeros(), 0);
146 /// ```
147 #[doc = concat!("[`ilog2`]: ", stringify!($SelfT), "::ilog2")]
148 #[stable(feature = "rust1", since = "1.0.0")]
149 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
150 #[must_use = "this returns the result of the operation, \
151 without modifying the original"]
152 #[inline(always)]
153 pub const fn leading_zeros(self) -> u32 {
154 return intrinsics::ctlz(self as $ActualT);
155 }
156
157 /// Returns the number of trailing zeros in the binary representation
158 /// of `self`.
159 ///
160 /// # Examples
161 ///
162 /// ```
163 #[doc = concat!("let n = 0b0101000", stringify!($SelfT), ";")]
164 /// assert_eq!(n.trailing_zeros(), 3);
165 ///
166 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
167 #[doc = concat!("assert_eq!(zero.trailing_zeros(), ", stringify!($BITS), ");")]
168 ///
169 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
170 #[doc = concat!("assert_eq!(max.trailing_zeros(), 0);")]
171 /// ```
172 #[stable(feature = "rust1", since = "1.0.0")]
173 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
174 #[must_use = "this returns the result of the operation, \
175 without modifying the original"]
176 #[inline(always)]
177 pub const fn trailing_zeros(self) -> u32 {
178 return intrinsics::cttz(self);
179 }
180
181 /// Returns the number of leading ones in the binary representation of `self`.
182 ///
183 /// # Examples
184 ///
185 /// ```
186 #[doc = concat!("let n = !(", stringify!($SelfT), "::MAX >> 2);")]
187 /// assert_eq!(n.leading_ones(), 2);
188 ///
189 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
190 /// assert_eq!(zero.leading_ones(), 0);
191 ///
192 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
193 #[doc = concat!("assert_eq!(max.leading_ones(), ", stringify!($BITS), ");")]
194 /// ```
195 #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
196 #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
197 #[must_use = "this returns the result of the operation, \
198 without modifying the original"]
199 #[inline(always)]
200 pub const fn leading_ones(self) -> u32 {
201 (!self).leading_zeros()
202 }
203
204 /// Returns the number of trailing ones in the binary representation
205 /// of `self`.
206 ///
207 /// # Examples
208 ///
209 /// ```
210 #[doc = concat!("let n = 0b1010111", stringify!($SelfT), ";")]
211 /// assert_eq!(n.trailing_ones(), 3);
212 ///
213 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
214 /// assert_eq!(zero.trailing_ones(), 0);
215 ///
216 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
217 #[doc = concat!("assert_eq!(max.trailing_ones(), ", stringify!($BITS), ");")]
218 /// ```
219 #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
220 #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
221 #[must_use = "this returns the result of the operation, \
222 without modifying the original"]
223 #[inline(always)]
224 pub const fn trailing_ones(self) -> u32 {
225 (!self).trailing_zeros()
226 }
227
228 /// Returns the minimum number of bits required to represent `self`.
229 ///
230 /// This method returns zero if `self` is zero.
231 ///
232 /// # Examples
233 ///
234 /// ```
235 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".bit_width(), 0);")]
236 #[doc = concat!("assert_eq!(0b111_", stringify!($SelfT), ".bit_width(), 3);")]
237 #[doc = concat!("assert_eq!(0b1110_", stringify!($SelfT), ".bit_width(), 4);")]
238 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.bit_width(), ", stringify!($BITS), ");")]
239 /// ```
240 #[stable(feature = "uint_bit_width", since = "CURRENT_RUSTC_VERSION")]
241 #[rustc_const_stable(feature = "uint_bit_width", since = "CURRENT_RUSTC_VERSION")]
242 #[must_use = "this returns the result of the operation, \
243 without modifying the original"]
244 #[inline(always)]
245 pub const fn bit_width(self) -> u32 {
246 Self::BITS - self.leading_zeros()
247 }
248
249 /// Returns `self` with only the most significant bit set, or `0` if
250 /// the input is `0`.
251 ///
252 /// # Examples
253 ///
254 /// ```
255 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b_01100100;")]
256 ///
257 /// assert_eq!(n.isolate_highest_one(), 0b_01000000);
258 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".isolate_highest_one(), 0);")]
259 /// ```
260 #[stable(feature = "isolate_most_least_significant_one", since = "CURRENT_RUSTC_VERSION")]
261 #[rustc_const_stable(feature = "isolate_most_least_significant_one", since = "CURRENT_RUSTC_VERSION")]
262 #[must_use = "this returns the result of the operation, \
263 without modifying the original"]
264 #[inline(always)]
265 pub const fn isolate_highest_one(self) -> Self {
266 self & (((1 as $SelfT) << (<$SelfT>::BITS - 1)).wrapping_shr(self.leading_zeros()))
267 }
268
269 /// Returns `self` with only the least significant bit set, or `0` if
270 /// the input is `0`.
271 ///
272 /// # Examples
273 ///
274 /// ```
275 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b_01100100;")]
276 ///
277 /// assert_eq!(n.isolate_lowest_one(), 0b_00000100);
278 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".isolate_lowest_one(), 0);")]
279 /// ```
280 #[stable(feature = "isolate_most_least_significant_one", since = "CURRENT_RUSTC_VERSION")]
281 #[rustc_const_stable(feature = "isolate_most_least_significant_one", since = "CURRENT_RUSTC_VERSION")]
282 #[must_use = "this returns the result of the operation, \
283 without modifying the original"]
284 #[inline(always)]
285 pub const fn isolate_lowest_one(self) -> Self {
286 self & self.wrapping_neg()
287 }
288
289 /// Returns the index of the highest bit set to one in `self`, or `None`
290 /// if `self` is `0`.
291 ///
292 /// # Examples
293 ///
294 /// ```
295 #[doc = concat!("assert_eq!(0b0_", stringify!($SelfT), ".highest_one(), None);")]
296 #[doc = concat!("assert_eq!(0b1_", stringify!($SelfT), ".highest_one(), Some(0));")]
297 #[doc = concat!("assert_eq!(0b1_0000_", stringify!($SelfT), ".highest_one(), Some(4));")]
298 #[doc = concat!("assert_eq!(0b1_1111_", stringify!($SelfT), ".highest_one(), Some(4));")]
299 /// ```
300 #[stable(feature = "int_lowest_highest_one", since = "CURRENT_RUSTC_VERSION")]
301 #[rustc_const_stable(feature = "int_lowest_highest_one", since = "CURRENT_RUSTC_VERSION")]
302 #[must_use = "this returns the result of the operation, \
303 without modifying the original"]
304 #[inline(always)]
305 pub const fn highest_one(self) -> Option<u32> {
306 match NonZero::new(self) {
307 Some(v) => Some(v.highest_one()),
308 None => None,
309 }
310 }
311
312 /// Returns the index of the lowest bit set to one in `self`, or `None`
313 /// if `self` is `0`.
314 ///
315 /// # Examples
316 ///
317 /// ```
318 #[doc = concat!("assert_eq!(0b0_", stringify!($SelfT), ".lowest_one(), None);")]
319 #[doc = concat!("assert_eq!(0b1_", stringify!($SelfT), ".lowest_one(), Some(0));")]
320 #[doc = concat!("assert_eq!(0b1_0000_", stringify!($SelfT), ".lowest_one(), Some(4));")]
321 #[doc = concat!("assert_eq!(0b1_1111_", stringify!($SelfT), ".lowest_one(), Some(0));")]
322 /// ```
323 #[stable(feature = "int_lowest_highest_one", since = "CURRENT_RUSTC_VERSION")]
324 #[rustc_const_stable(feature = "int_lowest_highest_one", since = "CURRENT_RUSTC_VERSION")]
325 #[must_use = "this returns the result of the operation, \
326 without modifying the original"]
327 #[inline(always)]
328 pub const fn lowest_one(self) -> Option<u32> {
329 match NonZero::new(self) {
330 Some(v) => Some(v.lowest_one()),
331 None => None,
332 }
333 }
334
335 /// Returns the bit pattern of `self` reinterpreted as a signed integer of the same size.
336 ///
337 /// This produces the same result as an `as` cast, but ensures that the bit-width remains
338 /// the same.
339 ///
340 /// # Examples
341 ///
342 /// ```
343 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
344 ///
345 #[doc = concat!("assert_eq!(n.cast_signed(), -1", stringify!($SignedT), ");")]
346 /// ```
347 #[stable(feature = "integer_sign_cast", since = "1.87.0")]
348 #[rustc_const_stable(feature = "integer_sign_cast", since = "1.87.0")]
349 #[must_use = "this returns the result of the operation, \
350 without modifying the original"]
351 #[inline(always)]
352 pub const fn cast_signed(self) -> $SignedT {
353 self as $SignedT
354 }
355
356 /// Saturating conversion of `self` to a signed integer of the same size.
357 ///
358 /// The signed integer's maximum value is returned if `self` is larger
359 /// than the maximum positive value representable by the signed integer.
360 ///
361 /// For other kinds of signed integer casts, see
362 /// [`cast_signed`](Self::cast_signed),
363 /// [`checked_cast_signed`](Self::checked_cast_signed),
364 /// or [`strict_cast_signed`](Self::strict_cast_signed).
365 ///
366 /// # Examples
367 ///
368 /// ```
369 /// #![feature(integer_cast_extras)]
370 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
371 ///
372 #[doc = concat!("assert_eq!(n.saturating_cast_signed(), ", stringify!($SignedT), "::MAX);")]
373 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".saturating_cast_signed(), 64", stringify!($SignedT), ");")]
374 /// ```
375 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
376 #[unstable(feature = "integer_cast_extras", issue = "154650")]
377 #[must_use = "this returns the result of the operation, \
378 without modifying the original"]
379 #[inline(always)]
380 pub const fn saturating_cast_signed(self) -> $SignedT {
381 // Clamp to the signed integer max size, which is ActualT::MAX >> 1.
382 if self <= <$SignedT>::MAX.cast_unsigned() {
383 self.cast_signed()
384 } else {
385 <$SignedT>::MAX
386 }
387 }
388
389 /// Checked conversion of `self` to a signed integer of the same size,
390 /// returning `None` if `self` is larger than the signed integer's
391 /// maximum value.
392 ///
393 /// For other kinds of signed integer casts, see
394 /// [`cast_signed`](Self::cast_signed),
395 /// [`saturating_cast_signed`](Self::saturating_cast_signed),
396 /// or [`strict_cast_signed`](Self::strict_cast_signed).
397 ///
398 /// # Examples
399 ///
400 /// ```
401 /// #![feature(integer_cast_extras)]
402 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
403 ///
404 #[doc = concat!("assert_eq!(n.checked_cast_signed(), None);")]
405 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_cast_signed(), Some(64", stringify!($SignedT), "));")]
406 /// ```
407 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
408 #[unstable(feature = "integer_cast_extras", issue = "154650")]
409 #[must_use = "this returns the result of the operation, \
410 without modifying the original"]
411 #[inline(always)]
412 pub const fn checked_cast_signed(self) -> Option<$SignedT> {
413 if self <= <$SignedT>::MAX.cast_unsigned() {
414 Some(self.cast_signed())
415 } else {
416 None
417 }
418 }
419
420 /// Strict conversion of `self` to a signed integer of the same size,
421 /// which panics if `self` is larger than the signed integer's maximum
422 /// value.
423 ///
424 /// For other kinds of signed integer casts, see
425 /// [`cast_signed`](Self::cast_signed),
426 /// [`checked_cast_signed`](Self::checked_cast_signed),
427 /// or [`saturating_cast_signed`](Self::saturating_cast_signed).
428 ///
429 /// # Examples
430 ///
431 /// ```should_panic
432 /// #![feature(integer_cast_extras)]
433 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_cast_signed();")]
434 /// ```
435 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
436 #[unstable(feature = "integer_cast_extras", issue = "154650")]
437 #[must_use = "this returns the result of the operation, \
438 without modifying the original"]
439 #[inline]
440 #[track_caller]
441 pub const fn strict_cast_signed(self) -> $SignedT {
442 match self.checked_cast_signed() {
443 Some(n) => n,
444 None => imp::overflow_panic::cast_integer(),
445 }
446 }
447
448 /// Shifts the bits to the left by a specified amount, `n`,
449 /// wrapping the truncated bits to the end of the resulting integer.
450 ///
451 /// `rotate_left(n)` is equivalent to applying `rotate_left(1)` a total of `n` times. In
452 /// particular, a rotation by the number of bits in `self` returns the input value
453 /// unchanged.
454 ///
455 /// Please note this isn't the same operation as the `<<` shifting operator!
456 ///
457 /// # Examples
458 ///
459 /// ```
460 #[doc = concat!("let n = ", $rot_op, stringify!($SelfT), ";")]
461 #[doc = concat!("let m = ", $rot_result, ";")]
462 ///
463 #[doc = concat!("assert_eq!(n.rotate_left(", $rot, "), m);")]
464 #[doc = concat!("assert_eq!(n.rotate_left(1024), n);")]
465 /// ```
466 #[stable(feature = "rust1", since = "1.0.0")]
467 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
468 #[must_use = "this returns the result of the operation, \
469 without modifying the original"]
470 #[inline(always)]
471 #[rustc_allow_const_fn_unstable(const_trait_impl)] // for the intrinsic fallback
472 pub const fn rotate_left(self, n: u32) -> Self {
473 return intrinsics::rotate_left(self, n);
474 }
475
476 /// Shifts the bits to the right by a specified amount, `n`,
477 /// wrapping the truncated bits to the beginning of the resulting
478 /// integer.
479 ///
480 /// `rotate_right(n)` is equivalent to applying `rotate_right(1)` a total of `n` times. In
481 /// particular, a rotation by the number of bits in `self` returns the input value
482 /// unchanged.
483 ///
484 /// Please note this isn't the same operation as the `>>` shifting operator!
485 ///
486 /// # Examples
487 ///
488 /// ```
489 #[doc = concat!("let n = ", $rot_result, stringify!($SelfT), ";")]
490 #[doc = concat!("let m = ", $rot_op, ";")]
491 ///
492 #[doc = concat!("assert_eq!(n.rotate_right(", $rot, "), m);")]
493 #[doc = concat!("assert_eq!(n.rotate_right(1024), n);")]
494 /// ```
495 #[stable(feature = "rust1", since = "1.0.0")]
496 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
497 #[must_use = "this returns the result of the operation, \
498 without modifying the original"]
499 #[inline(always)]
500 #[rustc_allow_const_fn_unstable(const_trait_impl)] // for the intrinsic fallback
501 pub const fn rotate_right(self, n: u32) -> Self {
502 return intrinsics::rotate_right(self, n);
503 }
504
505 /// Performs a left funnel shift (concatenates `self` with `rhs`, with `self`
506 /// making up the most significant half, then shifts the combined value left
507 /// by `n`, and most significant half is extracted to produce the result).
508 ///
509 /// Please note this isn't the same operation as the `<<` shifting operator or
510 /// [`rotate_left`](Self::rotate_left), although `a.funnel_shl(a, n)` is *equivalent*
511 /// to `a.rotate_left(n)`.
512 ///
513 /// # Panics
514 ///
515 /// If `n` is greater than or equal to the number of bits in `self`
516 ///
517 /// # Examples
518 ///
519 /// Basic usage:
520 ///
521 /// ```
522 /// #![feature(funnel_shifts)]
523 #[doc = concat!("let a = ", $rot_op, stringify!($SelfT), ";")]
524 #[doc = concat!("let b = ", $fsh_op, stringify!($SelfT), ";")]
525 #[doc = concat!("let m = ", $fshl_result, ";")]
526 ///
527 #[doc = concat!("assert_eq!(a.funnel_shl(b, ", $rot, "), m);")]
528 /// ```
529 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
530 #[unstable(feature = "funnel_shifts", issue = "145686")]
531 #[must_use = "this returns the result of the operation, \
532 without modifying the original"]
533 #[inline(always)]
534 pub const fn funnel_shl(self, rhs: Self, n: u32) -> Self {
535 assert!(n < Self::BITS, "attempt to funnel shift left with overflow");
536 // SAFETY: just checked that `shift` is in-range
537 unsafe { self.unchecked_funnel_shl(rhs, n) }
538 }
539
540 /// Performs a right funnel shift (concatenates `self` and `rhs`, with `self`
541 /// making up the most significant half, then shifts the combined value right
542 /// by `n`, and least significant half is extracted to produce the result).
543 ///
544 /// Please note this isn't the same operation as the `>>` shifting operator or
545 /// [`rotate_right`](Self::rotate_right), although `a.funnel_shr(a, n)` is *equivalent*
546 /// to `a.rotate_right(n)`.
547 ///
548 /// # Panics
549 ///
550 /// If `n` is greater than or equal to the number of bits in `self`
551 ///
552 /// # Examples
553 ///
554 /// Basic usage:
555 ///
556 /// ```
557 /// #![feature(funnel_shifts)]
558 #[doc = concat!("let a = ", $rot_op, stringify!($SelfT), ";")]
559 #[doc = concat!("let b = ", $fsh_op, stringify!($SelfT), ";")]
560 #[doc = concat!("let m = ", $fshr_result, ";")]
561 ///
562 #[doc = concat!("assert_eq!(a.funnel_shr(b, ", $rot, "), m);")]
563 /// ```
564 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
565 #[unstable(feature = "funnel_shifts", issue = "145686")]
566 #[must_use = "this returns the result of the operation, \
567 without modifying the original"]
568 #[inline(always)]
569 pub const fn funnel_shr(self, rhs: Self, n: u32) -> Self {
570 assert!(n < Self::BITS, "attempt to funnel shift right with overflow");
571 // SAFETY: just checked that `shift` is in-range
572 unsafe { self.unchecked_funnel_shr(rhs, n) }
573 }
574
575 /// Unchecked funnel shift left.
576 ///
577 /// # Safety
578 ///
579 /// This results in undefined behavior if `n` is greater than or equal to
580 #[doc = concat!("`", stringify!($SelfT) , "::BITS`,")]
581 /// i.e. when [`funnel_shl`](Self::funnel_shl) would panic.
582 ///
583 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
584 #[unstable(feature = "funnel_shifts", issue = "145686")]
585 #[must_use = "this returns the result of the operation, \
586 without modifying the original"]
587 #[inline(always)]
588 #[track_caller]
589 pub const unsafe fn unchecked_funnel_shl(self, low: Self, n: u32) -> Self {
590 assert_unsafe_precondition!(
591 check_language_ub,
592 concat!(stringify!($SelfT), "::unchecked_funnel_shl cannot overflow"),
593 (n: u32 = n) => n < <$ActualT>::BITS,
594 );
595
596 // SAFETY: this is guaranteed to be safe by the caller.
597 unsafe {
598 intrinsics::unchecked_funnel_shl(self, low, n)
599 }
600 }
601
602 /// Unchecked funnel shift right.
603 ///
604 /// # Safety
605 ///
606 /// This results in undefined behavior if `n` is greater than or equal to
607 #[doc = concat!("`", stringify!($SelfT) , "::BITS`,")]
608 /// i.e. when [`funnel_shr`](Self::funnel_shr) would panic.
609 ///
610 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
611 #[unstable(feature = "funnel_shifts", issue = "145686")]
612 #[must_use = "this returns the result of the operation, \
613 without modifying the original"]
614 #[inline(always)]
615 #[track_caller]
616 pub const unsafe fn unchecked_funnel_shr(self, low: Self, n: u32) -> Self {
617 assert_unsafe_precondition!(
618 check_language_ub,
619 concat!(stringify!($SelfT), "::unchecked_funnel_shr cannot overflow"),
620 (n: u32 = n) => n < <$ActualT>::BITS,
621 );
622
623 // SAFETY: this is guaranteed to be safe by the caller.
624 unsafe {
625 intrinsics::unchecked_funnel_shr(self, low, n)
626 }
627 }
628
629 /// Performs a carry-less multiplication, returning the lower bits.
630 ///
631 /// This operation is similar to long multiplication in base 2, except that exclusive or is
632 /// used instead of addition. The implementation is equivalent to:
633 ///
634 /// ```no_run
635 #[doc = concat!("pub fn carryless_mul(lhs: ", stringify!($SelfT), ", rhs: ", stringify!($SelfT), ") -> ", stringify!($SelfT), "{")]
636 /// let mut retval = 0;
637 #[doc = concat!(" for i in 0..", stringify!($SelfT), "::BITS {")]
638 /// if (rhs >> i) & 1 != 0 {
639 /// // long multiplication would use +=
640 /// retval ^= lhs << i;
641 /// }
642 /// }
643 /// retval
644 /// }
645 /// ```
646 ///
647 /// The actual implementation is more efficient, and on some platforms lowers directly to a
648 /// dedicated instruction.
649 ///
650 /// # Uses
651 ///
652 /// Carryless multiplication can be used to turn a bitmask of quote characters into a
653 /// bit mask of characters surrounded by quotes:
654 ///
655 /// ```no_run
656 /// r#"abc xxx "foobar" zzz "a"!"#; // input string
657 /// 0b0000000010000001000001010; // quote_mask
658 /// 0b0000000001111110000000100; // quote_mask.carryless_mul(!0) & !quote_mask
659 /// ```
660 ///
661 /// Another use is in cryptography, where carryless multiplication allows for efficient
662 /// implementations of polynomial multiplication in `GF(2)[X]`, the polynomial ring
663 /// over `GF(2)`.
664 ///
665 /// # Examples
666 ///
667 /// ```
668 /// #![feature(uint_carryless_mul)]
669 ///
670 #[doc = concat!("let a = ", $clmul_lhs, stringify!($SelfT), ";")]
671 #[doc = concat!("let b = ", $clmul_rhs, stringify!($SelfT), ";")]
672 ///
673 #[doc = concat!("assert_eq!(a.carryless_mul(b), ", $clmul_result, ");")]
674 /// ```
675 #[rustc_const_unstable(feature = "uint_carryless_mul", issue = "152080")]
676 #[doc(alias = "clmul")]
677 #[unstable(feature = "uint_carryless_mul", issue = "152080")]
678 #[must_use = "this returns the result of the operation, \
679 without modifying the original"]
680 #[inline(always)]
681 pub const fn carryless_mul(self, rhs: Self) -> Self {
682 intrinsics::carryless_mul(self, rhs)
683 }
684
685 /// Reverses the byte order of the integer.
686 ///
687 /// # Examples
688 ///
689 /// ```
690 #[doc = concat!("let n = ", $swap_op, stringify!($SelfT), ";")]
691 /// let m = n.swap_bytes();
692 ///
693 #[doc = concat!("assert_eq!(m, ", $swapped, ");")]
694 /// ```
695 #[stable(feature = "rust1", since = "1.0.0")]
696 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
697 #[must_use = "this returns the result of the operation, \
698 without modifying the original"]
699 #[inline(always)]
700 pub const fn swap_bytes(self) -> Self {
701 intrinsics::bswap(self as $ActualT) as Self
702 }
703
704 /// Returns an integer with the bit locations specified by `mask` packed
705 /// contiguously into the least significant bits of the result.
706 /// ```
707 /// #![feature(uint_gather_scatter_bits)]
708 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b1011_1100;")]
709 ///
710 /// assert_eq!(n.extract_bits(0b0010_0100), 0b0000_0011);
711 /// assert_eq!(n.extract_bits(0xF0), 0b0000_1011);
712 /// ```
713 #[unstable(feature = "uint_gather_scatter_bits", issue = "149069")]
714 #[must_use = "this returns the result of the operation, \
715 without modifying the original"]
716 #[inline]
717 pub const fn extract_bits(self, mask: Self) -> Self {
718 imp::int_bits::$ActualT::extract_impl(self as $ActualT, mask as $ActualT) as $SelfT
719 }
720
721 /// Returns an integer with the least significant bits of `self`
722 /// distributed to the bit locations specified by `mask`.
723 /// ```
724 /// #![feature(uint_gather_scatter_bits)]
725 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b1010_1101;")]
726 ///
727 /// assert_eq!(n.deposit_bits(0b0101_0101), 0b0101_0001);
728 /// assert_eq!(n.deposit_bits(0xF0), 0b1101_0000);
729 /// ```
730 #[unstable(feature = "uint_gather_scatter_bits", issue = "149069")]
731 #[must_use = "this returns the result of the operation, \
732 without modifying the original"]
733 #[inline]
734 pub const fn deposit_bits(self, mask: Self) -> Self {
735 imp::int_bits::$ActualT::deposit_impl(self as $ActualT, mask as $ActualT) as $SelfT
736 }
737
738 /// Reverses the order of bits in the integer. The least significant bit becomes the most significant bit,
739 /// second least-significant bit becomes second most-significant bit, etc.
740 ///
741 /// # Examples
742 ///
743 /// ```
744 #[doc = concat!("let n = ", $swap_op, stringify!($SelfT), ";")]
745 /// let m = n.reverse_bits();
746 ///
747 #[doc = concat!("assert_eq!(m, ", $reversed, ");")]
748 #[doc = concat!("assert_eq!(0, 0", stringify!($SelfT), ".reverse_bits());")]
749 /// ```
750 #[stable(feature = "reverse_bits", since = "1.37.0")]
751 #[rustc_const_stable(feature = "reverse_bits", since = "1.37.0")]
752 #[must_use = "this returns the result of the operation, \
753 without modifying the original"]
754 #[inline(always)]
755 pub const fn reverse_bits(self) -> Self {
756 intrinsics::bitreverse(self as $ActualT) as Self
757 }
758
759 /// Converts an integer from big endian to the target's endianness.
760 ///
761 /// On big endian this is a no-op. On little endian the bytes are
762 /// swapped.
763 ///
764 /// # Examples
765 ///
766 /// ```
767 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
768 ///
769 /// if cfg!(target_endian = "big") {
770 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_be(n), n)")]
771 /// } else {
772 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_be(n), n.swap_bytes())")]
773 /// }
774 /// ```
775 #[stable(feature = "rust1", since = "1.0.0")]
776 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
777 #[must_use]
778 #[inline(always)]
779 pub const fn from_be(x: Self) -> Self {
780 cfg_select! {
781 target_endian = "big" => x,
782 _ => x.swap_bytes(),
783 }
784 }
785
786 /// Converts an integer from little endian to the target's endianness.
787 ///
788 /// On little endian this is a no-op. On big endian the bytes are
789 /// swapped.
790 ///
791 /// # Examples
792 ///
793 /// ```
794 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
795 ///
796 /// if cfg!(target_endian = "little") {
797 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_le(n), n)")]
798 /// } else {
799 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_le(n), n.swap_bytes())")]
800 /// }
801 /// ```
802 #[stable(feature = "rust1", since = "1.0.0")]
803 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
804 #[must_use]
805 #[inline(always)]
806 pub const fn from_le(x: Self) -> Self {
807 cfg_select! {
808 target_endian = "little" => x,
809 _ => x.swap_bytes(),
810 }
811 }
812
813 /// Converts `self` to big endian from the target's endianness.
814 ///
815 /// On big endian this is a no-op. On little endian the bytes are
816 /// swapped.
817 ///
818 /// # Examples
819 ///
820 /// ```
821 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
822 ///
823 /// if cfg!(target_endian = "big") {
824 /// assert_eq!(n.to_be(), n)
825 /// } else {
826 /// assert_eq!(n.to_be(), n.swap_bytes())
827 /// }
828 /// ```
829 #[stable(feature = "rust1", since = "1.0.0")]
830 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
831 #[must_use = "this returns the result of the operation, \
832 without modifying the original"]
833 #[inline(always)]
834 pub const fn to_be(self) -> Self { // or not to be?
835 cfg_select! {
836 target_endian = "big" => self,
837 _ => self.swap_bytes(),
838 }
839 }
840
841 /// Converts `self` to little endian from the target's endianness.
842 ///
843 /// On little endian this is a no-op. On big endian the bytes are
844 /// swapped.
845 ///
846 /// # Examples
847 ///
848 /// ```
849 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
850 ///
851 /// if cfg!(target_endian = "little") {
852 /// assert_eq!(n.to_le(), n)
853 /// } else {
854 /// assert_eq!(n.to_le(), n.swap_bytes())
855 /// }
856 /// ```
857 #[stable(feature = "rust1", since = "1.0.0")]
858 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
859 #[must_use = "this returns the result of the operation, \
860 without modifying the original"]
861 #[inline(always)]
862 pub const fn to_le(self) -> Self {
863 cfg_select! {
864 target_endian = "little" => self,
865 _ => self.swap_bytes(),
866 }
867 }
868
869 /// Checked integer addition. Computes `self + rhs`, returning `None`
870 /// if overflow occurred.
871 ///
872 /// # Examples
873 ///
874 /// ```
875 #[doc = concat!(
876 "assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add(1), ",
877 "Some(", stringify!($SelfT), "::MAX - 1));"
878 )]
879 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add(3), None);")]
880 /// ```
881 #[stable(feature = "rust1", since = "1.0.0")]
882 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
883 #[must_use = "this returns the result of the operation, \
884 without modifying the original"]
885 #[inline]
886 pub const fn checked_add(self, rhs: Self) -> Option<Self> {
887 // This used to use `overflowing_add`, but that means it ends up being
888 // a `wrapping_add`, losing some optimization opportunities. Notably,
889 // phrasing it this way helps `.checked_add(1)` optimize to a check
890 // against `MAX` and a `add nuw`.
891 // Per <https://github.com/rust-lang/rust/pull/124114#issuecomment-2066173305>,
892 // LLVM is happy to re-form the intrinsic later if useful.
893
894 if intrinsics::unlikely(intrinsics::add_with_overflow(self, rhs).1) {
895 None
896 } else {
897 // SAFETY: Just checked it doesn't overflow
898 Some(unsafe { intrinsics::unchecked_add(self, rhs) })
899 }
900 }
901
902 /// Strict integer addition. Computes `self + rhs`, panicking
903 /// if overflow occurred.
904 ///
905 /// # Panics
906 ///
907 /// ## Overflow behavior
908 ///
909 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
910 ///
911 /// # Examples
912 ///
913 /// ```
914 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).strict_add(1), ", stringify!($SelfT), "::MAX - 1);")]
915 /// ```
916 ///
917 /// The following panics because of overflow:
918 ///
919 /// ```should_panic
920 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX - 2).strict_add(3);")]
921 /// ```
922 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
923 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
924 #[must_use = "this returns the result of the operation, \
925 without modifying the original"]
926 #[inline]
927 #[track_caller]
928 pub const fn strict_add(self, rhs: Self) -> Self {
929 let (a, b) = self.overflowing_add(rhs);
930 if b { imp::overflow_panic::add() } else { a }
931 }
932
933 /// Unchecked integer addition. Computes `self + rhs`, assuming overflow
934 /// cannot occur.
935 ///
936 /// Calling `x.unchecked_add(y)` is semantically equivalent to calling
937 /// `x.`[`checked_add`]`(y).`[`unwrap_unchecked`]`()`.
938 ///
939 /// If you're just trying to avoid the panic in debug mode, then **do not**
940 /// use this. Instead, you're looking for [`wrapping_add`].
941 ///
942 /// # Safety
943 ///
944 /// This results in undefined behavior when
945 #[doc = concat!("`self + rhs > ", stringify!($SelfT), "::MAX`,")]
946 /// i.e. when [`checked_add`] would return `None`.
947 ///
948 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
949 #[doc = concat!("[`checked_add`]: ", stringify!($SelfT), "::checked_add")]
950 #[doc = concat!("[`wrapping_add`]: ", stringify!($SelfT), "::wrapping_add")]
951 #[stable(feature = "unchecked_math", since = "1.79.0")]
952 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
953 #[must_use = "this returns the result of the operation, \
954 without modifying the original"]
955 #[inline(always)]
956 #[track_caller]
957 pub const unsafe fn unchecked_add(self, rhs: Self) -> Self {
958 assert_unsafe_precondition!(
959 check_language_ub,
960 concat!(stringify!($SelfT), "::unchecked_add cannot overflow"),
961 (
962 lhs: $SelfT = self,
963 rhs: $SelfT = rhs,
964 ) => !lhs.overflowing_add(rhs).1,
965 );
966
967 // SAFETY: this is guaranteed to be safe by the caller.
968 unsafe {
969 intrinsics::unchecked_add(self, rhs)
970 }
971 }
972
973 /// Checked addition with a signed integer. Computes `self + rhs`,
974 /// returning `None` if overflow occurred.
975 ///
976 /// # Examples
977 ///
978 /// ```
979 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_add_signed(2), Some(3));")]
980 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_add_signed(-2), None);")]
981 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add_signed(3), None);")]
982 /// ```
983 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
984 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
985 #[must_use = "this returns the result of the operation, \
986 without modifying the original"]
987 #[inline]
988 pub const fn checked_add_signed(self, rhs: $SignedT) -> Option<Self> {
989 let (a, b) = self.overflowing_add_signed(rhs);
990 if intrinsics::unlikely(b) { None } else { Some(a) }
991 }
992
993 /// Strict addition with a signed integer. Computes `self + rhs`,
994 /// panicking if overflow occurred.
995 ///
996 /// # Panics
997 ///
998 /// ## Overflow behavior
999 ///
1000 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1001 ///
1002 /// # Examples
1003 ///
1004 /// ```
1005 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".strict_add_signed(2), 3);")]
1006 /// ```
1007 ///
1008 /// The following panic because of overflow:
1009 ///
1010 /// ```should_panic
1011 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_add_signed(-2);")]
1012 /// ```
1013 ///
1014 /// ```should_panic
1015 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX - 2).strict_add_signed(3);")]
1016 /// ```
1017 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1018 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1019 #[must_use = "this returns the result of the operation, \
1020 without modifying the original"]
1021 #[inline]
1022 #[track_caller]
1023 pub const fn strict_add_signed(self, rhs: $SignedT) -> Self {
1024 let (a, b) = self.overflowing_add_signed(rhs);
1025 if b { imp::overflow_panic::add() } else { a }
1026 }
1027
1028 /// Checked integer subtraction. Computes `self - rhs`, returning
1029 /// `None` if overflow occurred.
1030 ///
1031 /// # Examples
1032 ///
1033 /// ```
1034 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub(1), Some(0));")]
1035 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_sub(1), None);")]
1036 /// ```
1037 #[stable(feature = "rust1", since = "1.0.0")]
1038 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1039 #[must_use = "this returns the result of the operation, \
1040 without modifying the original"]
1041 #[inline]
1042 pub const fn checked_sub(self, rhs: Self) -> Option<Self> {
1043 // Per PR#103299, there's no advantage to the `overflowing` intrinsic
1044 // for *unsigned* subtraction and we just emit the manual check anyway.
1045 // Thus, rather than using `overflowing_sub` that produces a wrapping
1046 // subtraction, check it ourself so we can use an unchecked one.
1047
1048 if self < rhs {
1049 None
1050 } else {
1051 // SAFETY: just checked this can't overflow
1052 Some(unsafe { intrinsics::unchecked_sub(self, rhs) })
1053 }
1054 }
1055
1056 /// Strict integer subtraction. Computes `self - rhs`, panicking if
1057 /// overflow occurred.
1058 ///
1059 /// # Panics
1060 ///
1061 /// ## Overflow behavior
1062 ///
1063 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1064 ///
1065 /// # Examples
1066 ///
1067 /// ```
1068 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".strict_sub(1), 0);")]
1069 /// ```
1070 ///
1071 /// The following panics because of overflow:
1072 ///
1073 /// ```should_panic
1074 #[doc = concat!("let _ = 0", stringify!($SelfT), ".strict_sub(1);")]
1075 /// ```
1076 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1077 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1078 #[must_use = "this returns the result of the operation, \
1079 without modifying the original"]
1080 #[inline]
1081 #[track_caller]
1082 pub const fn strict_sub(self, rhs: Self) -> Self {
1083 let (a, b) = self.overflowing_sub(rhs);
1084 if b { imp::overflow_panic::sub() } else { a }
1085 }
1086
1087 /// Unchecked integer subtraction. Computes `self - rhs`, assuming overflow
1088 /// cannot occur.
1089 ///
1090 /// Calling `x.unchecked_sub(y)` is semantically equivalent to calling
1091 /// `x.`[`checked_sub`]`(y).`[`unwrap_unchecked`]`()`.
1092 ///
1093 /// If you're just trying to avoid the panic in debug mode, then **do not**
1094 /// use this. Instead, you're looking for [`wrapping_sub`].
1095 ///
1096 /// If you find yourself writing code like this:
1097 ///
1098 /// ```
1099 /// # let foo = 30_u32;
1100 /// # let bar = 20;
1101 /// if foo >= bar {
1102 /// // SAFETY: just checked it will not overflow
1103 /// let diff = unsafe { foo.unchecked_sub(bar) };
1104 /// // ... use diff ...
1105 /// }
1106 /// ```
1107 ///
1108 /// Consider changing it to
1109 ///
1110 /// ```
1111 /// # let foo = 30_u32;
1112 /// # let bar = 20;
1113 /// if let Some(diff) = foo.checked_sub(bar) {
1114 /// // ... use diff ...
1115 /// }
1116 /// ```
1117 ///
1118 /// As that does exactly the same thing -- including telling the optimizer
1119 /// that the subtraction cannot overflow -- but avoids needing `unsafe`.
1120 ///
1121 /// # Safety
1122 ///
1123 /// This results in undefined behavior when
1124 #[doc = concat!("`self - rhs < ", stringify!($SelfT), "::MIN`,")]
1125 /// i.e. when [`checked_sub`] would return `None`.
1126 ///
1127 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
1128 #[doc = concat!("[`checked_sub`]: ", stringify!($SelfT), "::checked_sub")]
1129 #[doc = concat!("[`wrapping_sub`]: ", stringify!($SelfT), "::wrapping_sub")]
1130 #[stable(feature = "unchecked_math", since = "1.79.0")]
1131 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
1132 #[must_use = "this returns the result of the operation, \
1133 without modifying the original"]
1134 #[inline(always)]
1135 #[track_caller]
1136 pub const unsafe fn unchecked_sub(self, rhs: Self) -> Self {
1137 assert_unsafe_precondition!(
1138 check_language_ub,
1139 concat!(stringify!($SelfT), "::unchecked_sub cannot overflow"),
1140 (
1141 lhs: $SelfT = self,
1142 rhs: $SelfT = rhs,
1143 ) => !lhs.overflowing_sub(rhs).1,
1144 );
1145
1146 // SAFETY: this is guaranteed to be safe by the caller.
1147 unsafe {
1148 intrinsics::unchecked_sub(self, rhs)
1149 }
1150 }
1151
1152 /// Checked subtraction with a signed integer. Computes `self - rhs`,
1153 /// returning `None` if overflow occurred.
1154 ///
1155 /// # Examples
1156 ///
1157 /// ```
1158 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_signed(2), None);")]
1159 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_signed(-2), Some(3));")]
1160 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_sub_signed(-4), None);")]
1161 /// ```
1162 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
1163 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
1164 #[must_use = "this returns the result of the operation, \
1165 without modifying the original"]
1166 #[inline]
1167 pub const fn checked_sub_signed(self, rhs: $SignedT) -> Option<Self> {
1168 let (res, overflow) = self.overflowing_sub_signed(rhs);
1169
1170 if !overflow {
1171 Some(res)
1172 } else {
1173 None
1174 }
1175 }
1176
1177 /// Strict subtraction with a signed integer. Computes `self - rhs`,
1178 /// panicking if overflow occurred.
1179 ///
1180 /// # Panics
1181 ///
1182 /// ## Overflow behavior
1183 ///
1184 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1185 ///
1186 /// # Examples
1187 ///
1188 /// ```
1189 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".strict_sub_signed(2), 1);")]
1190 /// ```
1191 ///
1192 /// The following panic because of overflow:
1193 ///
1194 /// ```should_panic
1195 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_sub_signed(2);")]
1196 /// ```
1197 ///
1198 /// ```should_panic
1199 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX).strict_sub_signed(-1);")]
1200 /// ```
1201 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1202 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1203 #[must_use = "this returns the result of the operation, \
1204 without modifying the original"]
1205 #[inline]
1206 #[track_caller]
1207 pub const fn strict_sub_signed(self, rhs: $SignedT) -> Self {
1208 let (a, b) = self.overflowing_sub_signed(rhs);
1209 if b { imp::overflow_panic::sub() } else { a }
1210 }
1211
1212 #[doc = concat!(
1213 "Checked integer subtraction. Computes `self - rhs` and checks if the result fits into an [`",
1214 stringify!($SignedT), "`], returning `None` if overflow occurred."
1215 )]
1216 ///
1217 /// # Examples
1218 ///
1219 /// ```
1220 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".checked_signed_diff(2), Some(8));")]
1221 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_signed_diff(10), Some(-8));")]
1222 #[doc = concat!(
1223 "assert_eq!(",
1224 stringify!($SelfT),
1225 "::MAX.checked_signed_diff(",
1226 stringify!($SignedT),
1227 "::MAX as ",
1228 stringify!($SelfT),
1229 "), None);"
1230 )]
1231 #[doc = concat!(
1232 "assert_eq!((",
1233 stringify!($SignedT),
1234 "::MAX as ",
1235 stringify!($SelfT),
1236 ").checked_signed_diff(",
1237 stringify!($SelfT),
1238 "::MAX), Some(",
1239 stringify!($SignedT),
1240 "::MIN));"
1241 )]
1242 #[doc = concat!(
1243 "assert_eq!((",
1244 stringify!($SignedT),
1245 "::MAX as ",
1246 stringify!($SelfT),
1247 " + 1).checked_signed_diff(0), None);"
1248 )]
1249 #[doc = concat!(
1250 "assert_eq!(",
1251 stringify!($SelfT),
1252 "::MAX.checked_signed_diff(",
1253 stringify!($SelfT),
1254 "::MAX), Some(0));"
1255 )]
1256 /// ```
1257 #[stable(feature = "unsigned_signed_diff", since = "1.91.0")]
1258 #[rustc_const_stable(feature = "unsigned_signed_diff", since = "1.91.0")]
1259 #[inline]
1260 pub const fn checked_signed_diff(self, rhs: Self) -> Option<$SignedT> {
1261 let res = self.wrapping_sub(rhs) as $SignedT;
1262 let overflow = (self >= rhs) == (res < 0);
1263
1264 if !overflow {
1265 Some(res)
1266 } else {
1267 None
1268 }
1269 }
1270
1271 /// Checked integer multiplication. Computes `self * rhs`, returning
1272 /// `None` if overflow occurred.
1273 ///
1274 /// # Examples
1275 ///
1276 /// ```
1277 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_mul(1), Some(5));")]
1278 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_mul(2), None);")]
1279 /// ```
1280 #[stable(feature = "rust1", since = "1.0.0")]
1281 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1282 #[must_use = "this returns the result of the operation, \
1283 without modifying the original"]
1284 #[inline]
1285 pub const fn checked_mul(self, rhs: Self) -> Option<Self> {
1286 let (a, b) = self.overflowing_mul(rhs);
1287 if intrinsics::unlikely(b) { None } else { Some(a) }
1288 }
1289
1290 /// Strict integer multiplication. Computes `self * rhs`, panicking if
1291 /// overflow occurred.
1292 ///
1293 /// # Panics
1294 ///
1295 /// ## Overflow behavior
1296 ///
1297 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1298 ///
1299 /// # Examples
1300 ///
1301 /// ```
1302 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".strict_mul(1), 5);")]
1303 /// ```
1304 ///
1305 /// The following panics because of overflow:
1306 ///
1307 /// ``` should_panic
1308 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_mul(2);")]
1309 /// ```
1310 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1311 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1312 #[must_use = "this returns the result of the operation, \
1313 without modifying the original"]
1314 #[inline]
1315 #[track_caller]
1316 pub const fn strict_mul(self, rhs: Self) -> Self {
1317 let (a, b) = self.overflowing_mul(rhs);
1318 if b { imp::overflow_panic::mul() } else { a }
1319 }
1320
1321 /// Unchecked integer multiplication. Computes `self * rhs`, assuming overflow
1322 /// cannot occur.
1323 ///
1324 /// Calling `x.unchecked_mul(y)` is semantically equivalent to calling
1325 /// `x.`[`checked_mul`]`(y).`[`unwrap_unchecked`]`()`.
1326 ///
1327 /// If you're just trying to avoid the panic in debug mode, then **do not**
1328 /// use this. Instead, you're looking for [`wrapping_mul`].
1329 ///
1330 /// # Safety
1331 ///
1332 /// This results in undefined behavior when
1333 #[doc = concat!("`self * rhs > ", stringify!($SelfT), "::MAX`,")]
1334 /// i.e. when [`checked_mul`] would return `None`.
1335 ///
1336 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
1337 #[doc = concat!("[`checked_mul`]: ", stringify!($SelfT), "::checked_mul")]
1338 #[doc = concat!("[`wrapping_mul`]: ", stringify!($SelfT), "::wrapping_mul")]
1339 #[stable(feature = "unchecked_math", since = "1.79.0")]
1340 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
1341 #[must_use = "this returns the result of the operation, \
1342 without modifying the original"]
1343 #[inline(always)]
1344 #[track_caller]
1345 pub const unsafe fn unchecked_mul(self, rhs: Self) -> Self {
1346 assert_unsafe_precondition!(
1347 check_language_ub,
1348 concat!(stringify!($SelfT), "::unchecked_mul cannot overflow"),
1349 (
1350 lhs: $SelfT = self,
1351 rhs: $SelfT = rhs,
1352 ) => !lhs.overflowing_mul(rhs).1,
1353 );
1354
1355 // SAFETY: this is guaranteed to be safe by the caller.
1356 unsafe {
1357 intrinsics::unchecked_mul(self, rhs)
1358 }
1359 }
1360
1361 /// Checked integer division. Computes `self / rhs`, returning `None`
1362 /// if `rhs == 0`.
1363 ///
1364 /// # Examples
1365 ///
1366 /// ```
1367 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_div(2), Some(64));")]
1368 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_div(0), None);")]
1369 /// ```
1370 #[stable(feature = "rust1", since = "1.0.0")]
1371 #[rustc_const_stable(feature = "const_checked_int_div", since = "1.52.0")]
1372 #[must_use = "this returns the result of the operation, \
1373 without modifying the original"]
1374 #[inline]
1375 pub const fn checked_div(self, rhs: Self) -> Option<Self> {
1376 if intrinsics::unlikely(rhs == 0) {
1377 None
1378 } else {
1379 // SAFETY: div by zero has been checked above and unsigned types have no other
1380 // failure modes for division
1381 Some(unsafe { intrinsics::unchecked_div(self, rhs) })
1382 }
1383 }
1384
1385 /// Strict integer division. Computes `self / rhs`.
1386 ///
1387 /// Strict division on unsigned types is just normal division. There's no
1388 /// way overflow could ever happen. This function exists so that all
1389 /// operations are accounted for in the strict operations.
1390 ///
1391 /// # Panics
1392 ///
1393 /// This function will panic if `rhs` is zero.
1394 ///
1395 /// # Examples
1396 ///
1397 /// ```
1398 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_div(10), 10);")]
1399 /// ```
1400 ///
1401 /// The following panics because of division by zero:
1402 ///
1403 /// ```should_panic
1404 #[doc = concat!("let _ = (1", stringify!($SelfT), ").strict_div(0);")]
1405 /// ```
1406 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1407 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1408 #[must_use = "this returns the result of the operation, \
1409 without modifying the original"]
1410 #[inline(always)]
1411 #[track_caller]
1412 pub const fn strict_div(self, rhs: Self) -> Self {
1413 self / rhs
1414 }
1415
1416 /// Checked Euclidean division. Computes `self.div_euclid(rhs)`, returning `None`
1417 /// if `rhs == 0`.
1418 ///
1419 /// # Examples
1420 ///
1421 /// ```
1422 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_div_euclid(2), Some(64));")]
1423 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_div_euclid(0), None);")]
1424 /// ```
1425 #[stable(feature = "euclidean_division", since = "1.38.0")]
1426 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
1427 #[must_use = "this returns the result of the operation, \
1428 without modifying the original"]
1429 #[inline]
1430 pub const fn checked_div_euclid(self, rhs: Self) -> Option<Self> {
1431 if intrinsics::unlikely(rhs == 0) {
1432 None
1433 } else {
1434 Some(self.div_euclid(rhs))
1435 }
1436 }
1437
1438 /// Strict Euclidean division. Computes `self.div_euclid(rhs)`.
1439 ///
1440 /// Strict division on unsigned types is just normal division. There's no
1441 /// way overflow could ever happen. This function exists so that all
1442 /// operations are accounted for in the strict operations. Since, for the
1443 /// positive integers, all common definitions of division are equal, this
1444 /// is exactly equal to `self.strict_div(rhs)`.
1445 ///
1446 /// # Panics
1447 ///
1448 /// This function will panic if `rhs` is zero.
1449 ///
1450 /// # Examples
1451 ///
1452 /// ```
1453 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_div_euclid(10), 10);")]
1454 /// ```
1455 /// The following panics because of division by zero:
1456 ///
1457 /// ```should_panic
1458 #[doc = concat!("let _ = (1", stringify!($SelfT), ").strict_div_euclid(0);")]
1459 /// ```
1460 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1461 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1462 #[must_use = "this returns the result of the operation, \
1463 without modifying the original"]
1464 #[inline(always)]
1465 #[track_caller]
1466 pub const fn strict_div_euclid(self, rhs: Self) -> Self {
1467 self / rhs
1468 }
1469
1470 /// Checked integer division without remainder. Computes `self / rhs`,
1471 /// returning `None` if `rhs == 0` or if `self % rhs != 0`.
1472 ///
1473 /// # Examples
1474 ///
1475 /// ```
1476 /// #![feature(exact_div)]
1477 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(2), Some(32));")]
1478 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(32), Some(2));")]
1479 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(0), None);")]
1480 #[doc = concat!("assert_eq!(65", stringify!($SelfT), ".checked_div_exact(2), None);")]
1481 /// ```
1482 #[unstable(
1483 feature = "exact_div",
1484 issue = "139911",
1485 )]
1486 #[must_use = "this returns the result of the operation, \
1487 without modifying the original"]
1488 #[inline]
1489 pub const fn checked_div_exact(self, rhs: Self) -> Option<Self> {
1490 if intrinsics::unlikely(rhs == 0) {
1491 None
1492 } else {
1493 // SAFETY: division by zero is checked above
1494 unsafe {
1495 if intrinsics::unlikely(intrinsics::unchecked_rem(self, rhs) != 0) {
1496 None
1497 } else {
1498 Some(intrinsics::exact_div(self, rhs))
1499 }
1500 }
1501 }
1502 }
1503
1504 /// Integer division without remainder. Computes `self / rhs`, returning `None` if `self % rhs != 0`.
1505 ///
1506 /// # Panics
1507 ///
1508 /// This function will panic if `rhs == 0`.
1509 ///
1510 /// # Examples
1511 ///
1512 /// ```
1513 /// #![feature(exact_div)]
1514 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".div_exact(2), Some(32));")]
1515 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".div_exact(32), Some(2));")]
1516 #[doc = concat!("assert_eq!(65", stringify!($SelfT), ".div_exact(2), None);")]
1517 /// ```
1518 #[unstable(
1519 feature = "exact_div",
1520 issue = "139911",
1521 )]
1522 #[must_use = "this returns the result of the operation, \
1523 without modifying the original"]
1524 #[inline]
1525 #[rustc_inherit_overflow_checks]
1526 pub const fn div_exact(self, rhs: Self) -> Option<Self> {
1527 if self % rhs != 0 {
1528 None
1529 } else {
1530 Some(self / rhs)
1531 }
1532 }
1533
1534 /// Unchecked integer division without remainder. Computes `self / rhs`.
1535 ///
1536 /// # Safety
1537 ///
1538 /// This results in undefined behavior when `rhs == 0` or `self % rhs != 0`,
1539 /// i.e. when [`checked_div_exact`](Self::checked_div_exact) would return `None`.
1540 #[unstable(
1541 feature = "exact_div",
1542 issue = "139911",
1543 )]
1544 #[must_use = "this returns the result of the operation, \
1545 without modifying the original"]
1546 #[inline]
1547 pub const unsafe fn unchecked_div_exact(self, rhs: Self) -> Self {
1548 assert_unsafe_precondition!(
1549 check_language_ub,
1550 concat!(stringify!($SelfT), "::unchecked_div_exact divide by zero or leave a remainder"),
1551 (
1552 lhs: $SelfT = self,
1553 rhs: $SelfT = rhs,
1554 ) => rhs > 0 && lhs % rhs == 0,
1555 );
1556 // SAFETY: Same precondition
1557 unsafe { intrinsics::exact_div(self, rhs) }
1558 }
1559
1560 /// Checked integer remainder. Computes `self % rhs`, returning `None`
1561 /// if `rhs == 0`.
1562 ///
1563 /// # Examples
1564 ///
1565 /// ```
1566 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem(2), Some(1));")]
1567 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem(0), None);")]
1568 /// ```
1569 #[stable(feature = "wrapping", since = "1.7.0")]
1570 #[rustc_const_stable(feature = "const_checked_int_div", since = "1.52.0")]
1571 #[must_use = "this returns the result of the operation, \
1572 without modifying the original"]
1573 #[inline]
1574 pub const fn checked_rem(self, rhs: Self) -> Option<Self> {
1575 if intrinsics::unlikely(rhs == 0) {
1576 None
1577 } else {
1578 // SAFETY: div by zero has been checked above and unsigned types have no other
1579 // failure modes for division
1580 Some(unsafe { intrinsics::unchecked_rem(self, rhs) })
1581 }
1582 }
1583
1584 /// Strict integer remainder. Computes `self % rhs`.
1585 ///
1586 /// Strict remainder calculation on unsigned types is just the regular
1587 /// remainder calculation. There's no way overflow could ever happen.
1588 /// This function exists so that all operations are accounted for in the
1589 /// strict operations.
1590 ///
1591 /// # Panics
1592 ///
1593 /// This function will panic if `rhs` is zero.
1594 ///
1595 /// # Examples
1596 ///
1597 /// ```
1598 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_rem(10), 0);")]
1599 /// ```
1600 ///
1601 /// The following panics because of division by zero:
1602 ///
1603 /// ```should_panic
1604 #[doc = concat!("let _ = 5", stringify!($SelfT), ".strict_rem(0);")]
1605 /// ```
1606 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1607 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1608 #[must_use = "this returns the result of the operation, \
1609 without modifying the original"]
1610 #[inline(always)]
1611 #[track_caller]
1612 pub const fn strict_rem(self, rhs: Self) -> Self {
1613 self % rhs
1614 }
1615
1616 /// Checked Euclidean modulo. Computes `self.rem_euclid(rhs)`, returning `None`
1617 /// if `rhs == 0`.
1618 ///
1619 /// # Examples
1620 ///
1621 /// ```
1622 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem_euclid(2), Some(1));")]
1623 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem_euclid(0), None);")]
1624 /// ```
1625 #[stable(feature = "euclidean_division", since = "1.38.0")]
1626 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
1627 #[must_use = "this returns the result of the operation, \
1628 without modifying the original"]
1629 #[inline]
1630 pub const fn checked_rem_euclid(self, rhs: Self) -> Option<Self> {
1631 if intrinsics::unlikely(rhs == 0) {
1632 None
1633 } else {
1634 Some(self.rem_euclid(rhs))
1635 }
1636 }
1637
1638 /// Strict Euclidean modulo. Computes `self.rem_euclid(rhs)`.
1639 ///
1640 /// Strict modulo calculation on unsigned types is just the regular
1641 /// remainder calculation. There's no way overflow could ever happen.
1642 /// This function exists so that all operations are accounted for in the
1643 /// strict operations. Since, for the positive integers, all common
1644 /// definitions of division are equal, this is exactly equal to
1645 /// `self.strict_rem(rhs)`.
1646 ///
1647 /// # Panics
1648 ///
1649 /// This function will panic if `rhs` is zero.
1650 ///
1651 /// # Examples
1652 ///
1653 /// ```
1654 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_rem_euclid(10), 0);")]
1655 /// ```
1656 ///
1657 /// The following panics because of division by zero:
1658 ///
1659 /// ```should_panic
1660 #[doc = concat!("let _ = 5", stringify!($SelfT), ".strict_rem_euclid(0);")]
1661 /// ```
1662 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1663 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1664 #[must_use = "this returns the result of the operation, \
1665 without modifying the original"]
1666 #[inline(always)]
1667 #[track_caller]
1668 pub const fn strict_rem_euclid(self, rhs: Self) -> Self {
1669 self % rhs
1670 }
1671
1672 /// Same value as `self | other`, but UB if any bit position is set in both inputs.
1673 ///
1674 /// This is a situational micro-optimization for places where you'd rather
1675 /// use addition on some platforms and bitwise or on other platforms, based
1676 /// on exactly which instructions combine better with whatever else you're
1677 /// doing. Note that there's no reason to bother using this for places
1678 /// where it's clear from the operations involved that they can't overlap.
1679 /// For example, if you're combining `u16`s into a `u32` with
1680 /// `((a as u32) << 16) | (b as u32)`, that's fine, as the backend will
1681 /// know those sides of the `|` are disjoint without needing help.
1682 ///
1683 /// # Examples
1684 ///
1685 /// ```
1686 /// #![feature(disjoint_bitor)]
1687 ///
1688 /// // SAFETY: `1` and `4` have no bits in common.
1689 /// unsafe {
1690 #[doc = concat!(" assert_eq!(1_", stringify!($SelfT), ".unchecked_disjoint_bitor(4), 5);")]
1691 /// }
1692 /// ```
1693 ///
1694 /// # Safety
1695 ///
1696 /// Requires that `(self & other) == 0`, otherwise it's immediate UB.
1697 ///
1698 /// Equivalently, requires that `(self | other) == (self + other)`.
1699 #[unstable(feature = "disjoint_bitor", issue = "135758")]
1700 #[rustc_const_unstable(feature = "disjoint_bitor", issue = "135758")]
1701 #[inline]
1702 pub const unsafe fn unchecked_disjoint_bitor(self, other: Self) -> Self {
1703 assert_unsafe_precondition!(
1704 check_language_ub,
1705 concat!(stringify!($SelfT), "::unchecked_disjoint_bitor cannot have overlapping bits"),
1706 (
1707 lhs: $SelfT = self,
1708 rhs: $SelfT = other,
1709 ) => (lhs & rhs) == 0,
1710 );
1711
1712 // SAFETY: Same precondition
1713 unsafe { intrinsics::disjoint_bitor(self, other) }
1714 }
1715
1716 /// Returns the logarithm of the number with respect to an arbitrary base,
1717 /// rounded down.
1718 ///
1719 /// This method might not be optimized owing to implementation details;
1720 /// `ilog2` can produce results more efficiently for base 2, and `ilog10`
1721 /// can produce results more efficiently for base 10.
1722 ///
1723 /// # Panics
1724 ///
1725 /// This function will panic if `self` is zero, or if `base` is less than 2.
1726 ///
1727 /// # Examples
1728 ///
1729 /// ```
1730 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".ilog(5), 1);")]
1731 /// ```
1732 #[stable(feature = "int_log", since = "1.67.0")]
1733 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1734 #[must_use = "this returns the result of the operation, \
1735 without modifying the original"]
1736 #[inline]
1737 #[track_caller]
1738 pub const fn ilog(self, base: Self) -> u32 {
1739 assert!(base >= 2, "base of integer logarithm must be at least 2");
1740 if let Some(log) = self.checked_ilog(base) {
1741 log
1742 } else {
1743 imp::int_log10::panic_for_nonpositive_argument()
1744 }
1745 }
1746
1747 /// Returns the base 2 logarithm of the number, rounded down.
1748 ///
1749 /// # Panics
1750 ///
1751 /// This function will panic if `self` is zero.
1752 ///
1753 /// # Examples
1754 ///
1755 /// ```
1756 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".ilog2(), 1);")]
1757 /// ```
1758 #[stable(feature = "int_log", since = "1.67.0")]
1759 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1760 #[must_use = "this returns the result of the operation, \
1761 without modifying the original"]
1762 #[inline]
1763 #[track_caller]
1764 pub const fn ilog2(self) -> u32 {
1765 if let Some(log) = self.checked_ilog2() {
1766 log
1767 } else {
1768 imp::int_log10::panic_for_nonpositive_argument()
1769 }
1770 }
1771
1772 /// Returns the base 10 logarithm of the number, rounded down.
1773 ///
1774 /// # Panics
1775 ///
1776 /// This function will panic if `self` is zero.
1777 ///
1778 /// # Example
1779 ///
1780 /// ```
1781 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".ilog10(), 1);")]
1782 /// ```
1783 #[stable(feature = "int_log", since = "1.67.0")]
1784 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1785 #[must_use = "this returns the result of the operation, \
1786 without modifying the original"]
1787 #[inline]
1788 #[track_caller]
1789 pub const fn ilog10(self) -> u32 {
1790 if let Some(log) = self.checked_ilog10() {
1791 log
1792 } else {
1793 imp::int_log10::panic_for_nonpositive_argument()
1794 }
1795 }
1796
1797 /// Returns the logarithm of the number with respect to an arbitrary base,
1798 /// rounded down.
1799 ///
1800 /// Returns `None` if the number is zero, or if the base is not at least 2.
1801 ///
1802 /// This method might not be optimized owing to implementation details;
1803 /// `checked_ilog2` can produce results more efficiently for base 2, and
1804 /// `checked_ilog10` can produce results more efficiently for base 10.
1805 ///
1806 /// # Examples
1807 ///
1808 /// ```
1809 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_ilog(5), Some(1));")]
1810 /// ```
1811 #[stable(feature = "int_log", since = "1.67.0")]
1812 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1813 #[must_use = "this returns the result of the operation, \
1814 without modifying the original"]
1815 #[inline]
1816 pub const fn checked_ilog(self, base: Self) -> Option<u32> {
1817 // Inform compiler of optimizations when the base is known at
1818 // compile time and there's a cheaper method available.
1819 //
1820 // Note: Like all optimizations, this is not guaranteed to be
1821 // applied by the compiler. If you want those specific bases,
1822 // use `.checked_ilog2()` or `.checked_ilog10()` directly.
1823 if core::intrinsics::is_val_statically_known(base) {
1824 if base == 2 {
1825 return self.checked_ilog2();
1826 } else if base == 10 {
1827 return self.checked_ilog10();
1828 }
1829 }
1830
1831 if self <= 0 || base <= 1 {
1832 None
1833 } else if self < base {
1834 Some(0)
1835 } else {
1836 // Since base >= self, n >= 1
1837 let mut n = 1;
1838 let mut r = base;
1839
1840 // Optimization for 128 bit wide integers.
1841 if Self::BITS == 128 {
1842 // The following is a correct lower bound for ⌊log(base,self)⌋ because
1843 //
1844 // log(base,self) = log(2,self) / log(2,base)
1845 // ≥ ⌊log(2,self)⌋ / (⌊log(2,base)⌋ + 1)
1846 //
1847 // hence
1848 //
1849 // ⌊log(base,self)⌋ ≥ ⌊ ⌊log(2,self)⌋ / (⌊log(2,base)⌋ + 1) ⌋ .
1850 n = self.ilog2() / (base.ilog2() + 1);
1851 r = base.pow(n);
1852 }
1853
1854 while r <= self / base {
1855 n += 1;
1856 r *= base;
1857 }
1858 Some(n)
1859 }
1860 }
1861
1862 /// Returns the base 2 logarithm of the number, rounded down.
1863 ///
1864 /// Returns `None` if the number is zero.
1865 ///
1866 /// # Examples
1867 ///
1868 /// ```
1869 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_ilog2(), Some(1));")]
1870 /// ```
1871 #[stable(feature = "int_log", since = "1.67.0")]
1872 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1873 #[must_use = "this returns the result of the operation, \
1874 without modifying the original"]
1875 #[inline]
1876 pub const fn checked_ilog2(self) -> Option<u32> {
1877 match NonZero::new(self) {
1878 Some(x) => Some(x.ilog2()),
1879 None => None,
1880 }
1881 }
1882
1883 /// Returns the base 10 logarithm of the number, rounded down.
1884 ///
1885 /// Returns `None` if the number is zero.
1886 ///
1887 /// # Examples
1888 ///
1889 /// ```
1890 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".checked_ilog10(), Some(1));")]
1891 /// ```
1892 #[stable(feature = "int_log", since = "1.67.0")]
1893 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1894 #[must_use = "this returns the result of the operation, \
1895 without modifying the original"]
1896 #[inline]
1897 pub const fn checked_ilog10(self) -> Option<u32> {
1898 match NonZero::new(self) {
1899 Some(x) => Some(x.ilog10()),
1900 None => None,
1901 }
1902 }
1903
1904 /// Checked negation. Computes `-self`, returning `None` unless `self ==
1905 /// 0`.
1906 ///
1907 /// Note that negating any positive integer will overflow.
1908 ///
1909 /// # Examples
1910 ///
1911 /// ```
1912 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_neg(), Some(0));")]
1913 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_neg(), None);")]
1914 /// ```
1915 #[stable(feature = "wrapping", since = "1.7.0")]
1916 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1917 #[must_use = "this returns the result of the operation, \
1918 without modifying the original"]
1919 #[inline]
1920 pub const fn checked_neg(self) -> Option<Self> {
1921 let (a, b) = self.overflowing_neg();
1922 if intrinsics::unlikely(b) { None } else { Some(a) }
1923 }
1924
1925 /// Strict negation. Computes `-self`, panicking unless `self ==
1926 /// 0`.
1927 ///
1928 /// Note that negating any positive integer will overflow.
1929 ///
1930 /// # Panics
1931 ///
1932 /// ## Overflow behavior
1933 ///
1934 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1935 ///
1936 /// # Examples
1937 ///
1938 /// ```
1939 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".strict_neg(), 0);")]
1940 /// ```
1941 ///
1942 /// The following panics because of overflow:
1943 ///
1944 /// ```should_panic
1945 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_neg();")]
1946 /// ```
1947 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1948 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1949 #[must_use = "this returns the result of the operation, \
1950 without modifying the original"]
1951 #[inline]
1952 #[track_caller]
1953 pub const fn strict_neg(self) -> Self {
1954 let (a, b) = self.overflowing_neg();
1955 if b { imp::overflow_panic::neg() } else { a }
1956 }
1957
1958 /// Checked shift left. Computes `self << rhs`, returning `None`
1959 /// if `rhs` is larger than or equal to the number of bits in `self`.
1960 ///
1961 /// # Examples
1962 ///
1963 /// ```
1964 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".checked_shl(4), Some(0x10));")]
1965 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shl(129), None);")]
1966 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shl(", stringify!($BITS_MINUS_ONE), "), Some(0));")]
1967 /// ```
1968 #[stable(feature = "wrapping", since = "1.7.0")]
1969 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1970 #[must_use = "this returns the result of the operation, \
1971 without modifying the original"]
1972 #[inline]
1973 pub const fn checked_shl(self, rhs: u32) -> Option<Self> {
1974 // Not using overflowing_shl as that's a wrapping shift
1975 if rhs < Self::BITS {
1976 // SAFETY: just checked the RHS is in-range
1977 Some(unsafe { self.unchecked_shl(rhs) })
1978 } else {
1979 None
1980 }
1981 }
1982
1983 /// Strict shift left. Computes `self << rhs`, panicking if `rhs` is larger
1984 /// than or equal to the number of bits in `self`.
1985 ///
1986 /// # Panics
1987 ///
1988 /// ## Overflow behavior
1989 ///
1990 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1991 ///
1992 /// # Examples
1993 ///
1994 /// ```
1995 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".strict_shl(4), 0x10);")]
1996 /// ```
1997 ///
1998 /// The following panics because of overflow:
1999 ///
2000 /// ```should_panic
2001 #[doc = concat!("let _ = 0x10", stringify!($SelfT), ".strict_shl(129);")]
2002 /// ```
2003 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2004 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2005 #[must_use = "this returns the result of the operation, \
2006 without modifying the original"]
2007 #[inline]
2008 #[track_caller]
2009 pub const fn strict_shl(self, rhs: u32) -> Self {
2010 let (a, b) = self.overflowing_shl(rhs);
2011 if b { imp::overflow_panic::shl() } else { a }
2012 }
2013
2014 /// Unchecked shift left. Computes `self << rhs`, assuming that
2015 /// `rhs` is less than the number of bits in `self`.
2016 ///
2017 /// # Safety
2018 ///
2019 /// This results in undefined behavior if `rhs` is larger than
2020 /// or equal to the number of bits in `self`,
2021 /// i.e. when [`checked_shl`] would return `None`.
2022 ///
2023 #[doc = concat!("[`checked_shl`]: ", stringify!($SelfT), "::checked_shl")]
2024 #[stable(feature = "unchecked_shifts", since = "1.93.0")]
2025 #[rustc_const_stable(feature = "unchecked_shifts", since = "1.93.0")]
2026 #[must_use = "this returns the result of the operation, \
2027 without modifying the original"]
2028 #[inline(always)]
2029 #[track_caller]
2030 pub const unsafe fn unchecked_shl(self, rhs: u32) -> Self {
2031 assert_unsafe_precondition!(
2032 check_language_ub,
2033 concat!(stringify!($SelfT), "::unchecked_shl cannot overflow"),
2034 (
2035 rhs: u32 = rhs,
2036 ) => rhs < <$ActualT>::BITS,
2037 );
2038
2039 // SAFETY: this is guaranteed to be safe by the caller.
2040 unsafe {
2041 intrinsics::unchecked_shl(self, rhs)
2042 }
2043 }
2044
2045 /// Unbounded shift left. Computes `self << rhs`, without bounding the value of `rhs`.
2046 ///
2047 /// If `rhs` is larger or equal to the number of bits in `self`,
2048 /// the entire value is shifted out, and `0` is returned.
2049 ///
2050 /// # Examples
2051 ///
2052 /// ```
2053 #[doc = concat!("assert_eq!(0x1_", stringify!($SelfT), ".unbounded_shl(4), 0x10);")]
2054 #[doc = concat!("assert_eq!(0x1_", stringify!($SelfT), ".unbounded_shl(129), 0);")]
2055 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(0), 0b101);")]
2056 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(1), 0b1010);")]
2057 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(2), 0b10100);")]
2058 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shl(", stringify!($BITS), "), 0);")]
2059 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shl(1).unbounded_shl(", stringify!($BITS_MINUS_ONE), "), 0);")]
2060 ///
2061 #[doc = concat!("let start : ", stringify!($SelfT), " = 13;")]
2062 /// let mut running = start;
2063 /// for i in 0..160 {
2064 /// // The unbounded shift left by i is the same as `<< 1` i times
2065 /// assert_eq!(running, start.unbounded_shl(i));
2066 /// // Which is not always the case for a wrapping shift
2067 #[doc = concat!(" assert_eq!(running == start.wrapping_shl(i), i < ", stringify!($BITS), ");")]
2068 ///
2069 /// running <<= 1;
2070 /// }
2071 /// ```
2072 #[stable(feature = "unbounded_shifts", since = "1.87.0")]
2073 #[rustc_const_stable(feature = "unbounded_shifts", since = "1.87.0")]
2074 #[must_use = "this returns the result of the operation, \
2075 without modifying the original"]
2076 #[inline]
2077 pub const fn unbounded_shl(self, rhs: u32) -> $SelfT{
2078 if rhs < Self::BITS {
2079 // SAFETY:
2080 // rhs is just checked to be in-range above
2081 unsafe { self.unchecked_shl(rhs) }
2082 } else {
2083 0
2084 }
2085 }
2086
2087 /// Exact shift left. Computes `self << rhs` as long as it can be reversed losslessly.
2088 ///
2089 /// Returns `None` if any non-zero bits would be shifted out or if `rhs` >=
2090 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2091 /// Otherwise, returns `Some(self << rhs)`.
2092 ///
2093 /// # Examples
2094 ///
2095 /// ```
2096 /// #![feature(exact_bitshifts)]
2097 ///
2098 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".shl_exact(4), Some(0x10));")]
2099 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".shl_exact(129), None);")]
2100 /// ```
2101 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2102 #[must_use = "this returns the result of the operation, \
2103 without modifying the original"]
2104 #[inline]
2105 pub const fn shl_exact(self, rhs: u32) -> Option<$SelfT> {
2106 if rhs <= self.leading_zeros() && rhs < <$SelfT>::BITS {
2107 // SAFETY: rhs is checked above
2108 Some(unsafe { self.unchecked_shl(rhs) })
2109 } else {
2110 None
2111 }
2112 }
2113
2114 /// Unchecked exact shift left. Computes `self << rhs`, assuming the operation can be
2115 /// losslessly reversed `rhs` cannot be larger than
2116 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2117 ///
2118 /// # Safety
2119 ///
2120 /// This results in undefined behavior when `rhs > self.leading_zeros() || rhs >=
2121 #[doc = concat!(stringify!($SelfT), "::BITS`")]
2122 /// i.e. when
2123 #[doc = concat!("[`", stringify!($SelfT), "::shl_exact`]")]
2124 /// would return `None`.
2125 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2126 #[must_use = "this returns the result of the operation, \
2127 without modifying the original"]
2128 #[inline]
2129 pub const unsafe fn unchecked_shl_exact(self, rhs: u32) -> $SelfT {
2130 assert_unsafe_precondition!(
2131 check_library_ub,
2132 concat!(stringify!($SelfT), "::unchecked_shl_exact cannot shift out non-zero bits"),
2133 (
2134 zeros: u32 = self.leading_zeros(),
2135 bits: u32 = <$SelfT>::BITS,
2136 rhs: u32 = rhs,
2137 ) => rhs <= zeros && rhs < bits,
2138 );
2139
2140 // SAFETY: this is guaranteed to be safe by the caller
2141 unsafe { self.unchecked_shl(rhs) }
2142 }
2143
2144 /// Checked shift right. Computes `self >> rhs`, returning `None`
2145 /// if `rhs` is larger than or equal to the number of bits in `self`.
2146 ///
2147 /// # Examples
2148 ///
2149 /// ```
2150 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shr(4), Some(0x1));")]
2151 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shr(129), None);")]
2152 /// ```
2153 #[stable(feature = "wrapping", since = "1.7.0")]
2154 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
2155 #[must_use = "this returns the result of the operation, \
2156 without modifying the original"]
2157 #[inline]
2158 pub const fn checked_shr(self, rhs: u32) -> Option<Self> {
2159 // Not using overflowing_shr as that's a wrapping shift
2160 if rhs < Self::BITS {
2161 // SAFETY: just checked the RHS is in-range
2162 Some(unsafe { self.unchecked_shr(rhs) })
2163 } else {
2164 None
2165 }
2166 }
2167
2168 /// Strict shift right. Computes `self >> rhs`, panicking if `rhs` is
2169 /// larger than or equal to the number of bits in `self`.
2170 ///
2171 /// # Panics
2172 ///
2173 /// ## Overflow behavior
2174 ///
2175 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2176 ///
2177 /// # Examples
2178 ///
2179 /// ```
2180 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".strict_shr(4), 0x1);")]
2181 /// ```
2182 ///
2183 /// The following panics because of overflow:
2184 ///
2185 /// ```should_panic
2186 #[doc = concat!("let _ = 0x10", stringify!($SelfT), ".strict_shr(129);")]
2187 /// ```
2188 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2189 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2190 #[must_use = "this returns the result of the operation, \
2191 without modifying the original"]
2192 #[inline]
2193 #[track_caller]
2194 pub const fn strict_shr(self, rhs: u32) -> Self {
2195 let (a, b) = self.overflowing_shr(rhs);
2196 if b { imp::overflow_panic::shr() } else { a }
2197 }
2198
2199 /// Unchecked shift right. Computes `self >> rhs`, assuming that
2200 /// `rhs` is less than the number of bits in `self`.
2201 ///
2202 /// # Safety
2203 ///
2204 /// This results in undefined behavior if `rhs` is larger than
2205 /// or equal to the number of bits in `self`,
2206 /// i.e. when [`checked_shr`] would return `None`.
2207 ///
2208 #[doc = concat!("[`checked_shr`]: ", stringify!($SelfT), "::checked_shr")]
2209 #[stable(feature = "unchecked_shifts", since = "1.93.0")]
2210 #[rustc_const_stable(feature = "unchecked_shifts", since = "1.93.0")]
2211 #[must_use = "this returns the result of the operation, \
2212 without modifying the original"]
2213 #[inline(always)]
2214 #[track_caller]
2215 pub const unsafe fn unchecked_shr(self, rhs: u32) -> Self {
2216 assert_unsafe_precondition!(
2217 check_language_ub,
2218 concat!(stringify!($SelfT), "::unchecked_shr cannot overflow"),
2219 (
2220 rhs: u32 = rhs,
2221 ) => rhs < <$ActualT>::BITS,
2222 );
2223
2224 // SAFETY: this is guaranteed to be safe by the caller.
2225 unsafe {
2226 intrinsics::unchecked_shr(self, rhs)
2227 }
2228 }
2229
2230 /// Unbounded shift right. Computes `self >> rhs`, without bounding the value of `rhs`.
2231 ///
2232 /// If `rhs` is larger or equal to the number of bits in `self`,
2233 /// the entire value is shifted out, and `0` is returned.
2234 ///
2235 /// # Examples
2236 ///
2237 /// ```
2238 #[doc = concat!("assert_eq!(0x10_", stringify!($SelfT), ".unbounded_shr(4), 0x1);")]
2239 #[doc = concat!("assert_eq!(0x10_", stringify!($SelfT), ".unbounded_shr(129), 0);")]
2240 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(0), 0b1010);")]
2241 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(1), 0b101);")]
2242 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(2), 0b10);")]
2243 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shr(", stringify!($BITS), "), 0);")]
2244 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shr(1).unbounded_shr(", stringify!($BITS_MINUS_ONE), "), 0);")]
2245 ///
2246 #[doc = concat!("let start = ", stringify!($SelfT), "::rotate_right(13, 4);")]
2247 /// let mut running = start;
2248 /// for i in 0..160 {
2249 /// // The unbounded shift right by i is the same as `>> 1` i times
2250 /// assert_eq!(running, start.unbounded_shr(i));
2251 /// // Which is not always the case for a wrapping shift
2252 #[doc = concat!(" assert_eq!(running == start.wrapping_shr(i), i < ", stringify!($BITS), ");")]
2253 ///
2254 /// running >>= 1;
2255 /// }
2256 /// ```
2257 #[stable(feature = "unbounded_shifts", since = "1.87.0")]
2258 #[rustc_const_stable(feature = "unbounded_shifts", since = "1.87.0")]
2259 #[must_use = "this returns the result of the operation, \
2260 without modifying the original"]
2261 #[inline]
2262 pub const fn unbounded_shr(self, rhs: u32) -> $SelfT{
2263 if rhs < Self::BITS {
2264 // SAFETY:
2265 // rhs is just checked to be in-range above
2266 unsafe { self.unchecked_shr(rhs) }
2267 } else {
2268 0
2269 }
2270 }
2271
2272 /// Exact shift right. Computes `self >> rhs` as long as it can be reversed losslessly.
2273 ///
2274 /// Returns `None` if any non-zero bits would be shifted out or if `rhs` >=
2275 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2276 /// Otherwise, returns `Some(self >> rhs)`.
2277 ///
2278 /// # Examples
2279 ///
2280 /// ```
2281 /// #![feature(exact_bitshifts)]
2282 ///
2283 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".shr_exact(4), Some(0x1));")]
2284 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".shr_exact(5), None);")]
2285 /// ```
2286 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2287 #[must_use = "this returns the result of the operation, \
2288 without modifying the original"]
2289 #[inline]
2290 pub const fn shr_exact(self, rhs: u32) -> Option<$SelfT> {
2291 if rhs <= self.trailing_zeros() && rhs < <$SelfT>::BITS {
2292 // SAFETY: rhs is checked above
2293 Some(unsafe { self.unchecked_shr(rhs) })
2294 } else {
2295 None
2296 }
2297 }
2298
2299 /// Unchecked exact shift right. Computes `self >> rhs`, assuming the operation can be
2300 /// losslessly reversed and `rhs` cannot be larger than
2301 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2302 ///
2303 /// # Safety
2304 ///
2305 /// This results in undefined behavior when `rhs > self.trailing_zeros() || rhs >=
2306 #[doc = concat!(stringify!($SelfT), "::BITS`")]
2307 /// i.e. when
2308 #[doc = concat!("[`", stringify!($SelfT), "::shr_exact`]")]
2309 /// would return `None`.
2310 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2311 #[must_use = "this returns the result of the operation, \
2312 without modifying the original"]
2313 #[inline]
2314 pub const unsafe fn unchecked_shr_exact(self, rhs: u32) -> $SelfT {
2315 assert_unsafe_precondition!(
2316 check_library_ub,
2317 concat!(stringify!($SelfT), "::unchecked_shr_exact cannot shift out non-zero bits"),
2318 (
2319 zeros: u32 = self.trailing_zeros(),
2320 bits: u32 = <$SelfT>::BITS,
2321 rhs: u32 = rhs,
2322 ) => rhs <= zeros && rhs < bits,
2323 );
2324
2325 // SAFETY: this is guaranteed to be safe by the caller
2326 unsafe { self.unchecked_shr(rhs) }
2327 }
2328
2329 /// Checked exponentiation. Computes `self.pow(exp)`, returning `None` if
2330 /// overflow occurred.
2331 ///
2332 /// # Examples
2333 ///
2334 /// ```
2335 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_pow(5), Some(32));")]
2336 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".checked_pow(0), Some(1));")]
2337 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_pow(2), None);")]
2338 /// ```
2339 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2340 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2341 #[must_use = "this returns the result of the operation, \
2342 without modifying the original"]
2343 #[inline]
2344 pub const fn checked_pow(self, mut exp: u32) -> Option<Self> {
2345 if exp == 0 {
2346 return Some(1);
2347 }
2348 let mut base = self;
2349 let mut acc: Self = 1;
2350
2351 loop {
2352 if (exp & 1) == 1 {
2353 acc = try_opt!(acc.checked_mul(base));
2354 // since exp!=0, finally the exp must be 1.
2355 if exp == 1 {
2356 return Some(acc);
2357 }
2358 }
2359 exp /= 2;
2360 base = try_opt!(base.checked_mul(base));
2361 }
2362 }
2363
2364 /// Strict exponentiation. Computes `self.pow(exp)`, panicking if
2365 /// overflow occurred.
2366 ///
2367 /// # Panics
2368 ///
2369 /// ## Overflow behavior
2370 ///
2371 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2372 ///
2373 /// # Examples
2374 ///
2375 /// ```
2376 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".strict_pow(5), 32);")]
2377 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".strict_pow(0), 1);")]
2378 /// ```
2379 ///
2380 /// The following panics because of overflow:
2381 ///
2382 /// ```should_panic
2383 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_pow(2);")]
2384 /// ```
2385 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2386 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2387 #[must_use = "this returns the result of the operation, \
2388 without modifying the original"]
2389 #[inline]
2390 #[track_caller]
2391 pub const fn strict_pow(self, mut exp: u32) -> Self {
2392 if exp == 0 {
2393 return 1;
2394 }
2395 let mut base = self;
2396 let mut acc: Self = 1;
2397
2398 loop {
2399 if (exp & 1) == 1 {
2400 acc = acc.strict_mul(base);
2401 // since exp!=0, finally the exp must be 1.
2402 if exp == 1 {
2403 return acc;
2404 }
2405 }
2406 exp /= 2;
2407 base = base.strict_mul(base);
2408 }
2409 }
2410
2411 /// Saturating integer addition. Computes `self + rhs`, saturating at
2412 /// the numeric bounds instead of overflowing.
2413 ///
2414 /// # Examples
2415 ///
2416 /// ```
2417 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".saturating_add(1), 101);")]
2418 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.saturating_add(127), ", stringify!($SelfT), "::MAX);")]
2419 /// ```
2420 #[stable(feature = "rust1", since = "1.0.0")]
2421 #[must_use = "this returns the result of the operation, \
2422 without modifying the original"]
2423 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2424 #[inline(always)]
2425 pub const fn saturating_add(self, rhs: Self) -> Self {
2426 intrinsics::saturating_add(self, rhs)
2427 }
2428
2429 /// Saturating addition with a signed integer. Computes `self + rhs`,
2430 /// saturating at the numeric bounds instead of overflowing.
2431 ///
2432 /// # Examples
2433 ///
2434 /// ```
2435 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_add_signed(2), 3);")]
2436 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_add_signed(-2), 0);")]
2437 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).saturating_add_signed(4), ", stringify!($SelfT), "::MAX);")]
2438 /// ```
2439 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
2440 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
2441 #[must_use = "this returns the result of the operation, \
2442 without modifying the original"]
2443 #[inline]
2444 pub const fn saturating_add_signed(self, rhs: $SignedT) -> Self {
2445 let (res, overflow) = self.overflowing_add(rhs as Self);
2446 if overflow == (rhs < 0) {
2447 res
2448 } else if overflow {
2449 Self::MAX
2450 } else {
2451 0
2452 }
2453 }
2454
2455 /// Saturating integer subtraction. Computes `self - rhs`, saturating
2456 /// at the numeric bounds instead of overflowing.
2457 ///
2458 /// # Examples
2459 ///
2460 /// ```
2461 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".saturating_sub(27), 73);")]
2462 #[doc = concat!("assert_eq!(13", stringify!($SelfT), ".saturating_sub(127), 0);")]
2463 /// ```
2464 #[stable(feature = "rust1", since = "1.0.0")]
2465 #[must_use = "this returns the result of the operation, \
2466 without modifying the original"]
2467 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2468 #[inline(always)]
2469 pub const fn saturating_sub(self, rhs: Self) -> Self {
2470 intrinsics::saturating_sub(self, rhs)
2471 }
2472
2473 /// Saturating integer subtraction. Computes `self` - `rhs`, saturating at
2474 /// the numeric bounds instead of overflowing.
2475 ///
2476 /// # Examples
2477 ///
2478 /// ```
2479 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_sub_signed(2), 0);")]
2480 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_sub_signed(-2), 3);")]
2481 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).saturating_sub_signed(-4), ", stringify!($SelfT), "::MAX);")]
2482 /// ```
2483 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2484 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2485 #[must_use = "this returns the result of the operation, \
2486 without modifying the original"]
2487 #[inline]
2488 pub const fn saturating_sub_signed(self, rhs: $SignedT) -> Self {
2489 let (res, overflow) = self.overflowing_sub_signed(rhs);
2490
2491 if !overflow {
2492 res
2493 } else if rhs < 0 {
2494 Self::MAX
2495 } else {
2496 0
2497 }
2498 }
2499
2500 /// Saturating integer multiplication. Computes `self * rhs`,
2501 /// saturating at the numeric bounds instead of overflowing.
2502 ///
2503 /// # Examples
2504 ///
2505 /// ```
2506 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".saturating_mul(10), 20);")]
2507 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX).saturating_mul(10), ", stringify!($SelfT),"::MAX);")]
2508 /// ```
2509 #[stable(feature = "wrapping", since = "1.7.0")]
2510 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2511 #[must_use = "this returns the result of the operation, \
2512 without modifying the original"]
2513 #[inline]
2514 pub const fn saturating_mul(self, rhs: Self) -> Self {
2515 match self.checked_mul(rhs) {
2516 Some(x) => x,
2517 None => Self::MAX,
2518 }
2519 }
2520
2521 /// Saturating integer division. Computes `self / rhs`, saturating at the
2522 /// numeric bounds instead of overflowing.
2523 ///
2524 /// # Panics
2525 ///
2526 /// This function will panic if `rhs` is zero.
2527 ///
2528 /// # Examples
2529 ///
2530 /// ```
2531 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".saturating_div(2), 2);")]
2532 ///
2533 /// ```
2534 #[stable(feature = "saturating_div", since = "1.58.0")]
2535 #[rustc_const_stable(feature = "saturating_div", since = "1.58.0")]
2536 #[must_use = "this returns the result of the operation, \
2537 without modifying the original"]
2538 #[inline]
2539 #[track_caller]
2540 pub const fn saturating_div(self, rhs: Self) -> Self {
2541 // on unsigned types, there is no overflow in integer division
2542 self.wrapping_div(rhs)
2543 }
2544
2545 /// Saturating integer exponentiation. Computes `self.pow(exp)`,
2546 /// saturating at the numeric bounds instead of overflowing.
2547 ///
2548 /// # Examples
2549 ///
2550 /// ```
2551 #[doc = concat!("assert_eq!(4", stringify!($SelfT), ".saturating_pow(3), 64);")]
2552 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".saturating_pow(0), 1);")]
2553 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.saturating_pow(2), ", stringify!($SelfT), "::MAX);")]
2554 /// ```
2555 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2556 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2557 #[must_use = "this returns the result of the operation, \
2558 without modifying the original"]
2559 #[inline]
2560 pub const fn saturating_pow(self, exp: u32) -> Self {
2561 match self.checked_pow(exp) {
2562 Some(x) => x,
2563 None => Self::MAX,
2564 }
2565 }
2566
2567 /// Wrapping (modular) addition. Computes `self + rhs`,
2568 /// wrapping around at the boundary of the type.
2569 ///
2570 /// # Examples
2571 ///
2572 /// ```
2573 #[doc = concat!("assert_eq!(200", stringify!($SelfT), ".wrapping_add(55), 255);")]
2574 #[doc = concat!("assert_eq!(200", stringify!($SelfT), ".wrapping_add(", stringify!($SelfT), "::MAX), 199);")]
2575 /// ```
2576 #[stable(feature = "rust1", since = "1.0.0")]
2577 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2578 #[must_use = "this returns the result of the operation, \
2579 without modifying the original"]
2580 #[inline(always)]
2581 pub const fn wrapping_add(self, rhs: Self) -> Self {
2582 intrinsics::wrapping_add(self, rhs)
2583 }
2584
2585 /// Wrapping (modular) addition with a signed integer. Computes
2586 /// `self + rhs`, wrapping around at the boundary of the type.
2587 ///
2588 /// # Examples
2589 ///
2590 /// ```
2591 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_add_signed(2), 3);")]
2592 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_add_signed(-2), ", stringify!($SelfT), "::MAX);")]
2593 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).wrapping_add_signed(4), 1);")]
2594 /// ```
2595 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
2596 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
2597 #[must_use = "this returns the result of the operation, \
2598 without modifying the original"]
2599 #[inline]
2600 pub const fn wrapping_add_signed(self, rhs: $SignedT) -> Self {
2601 self.wrapping_add(rhs as Self)
2602 }
2603
2604 /// Wrapping (modular) subtraction. Computes `self - rhs`,
2605 /// wrapping around at the boundary of the type.
2606 ///
2607 /// # Examples
2608 ///
2609 /// ```
2610 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_sub(100), 0);")]
2611 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_sub(", stringify!($SelfT), "::MAX), 101);")]
2612 /// ```
2613 #[stable(feature = "rust1", since = "1.0.0")]
2614 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2615 #[must_use = "this returns the result of the operation, \
2616 without modifying the original"]
2617 #[inline(always)]
2618 pub const fn wrapping_sub(self, rhs: Self) -> Self {
2619 intrinsics::wrapping_sub(self, rhs)
2620 }
2621
2622 /// Wrapping (modular) subtraction with a signed integer. Computes
2623 /// `self - rhs`, wrapping around at the boundary of the type.
2624 ///
2625 /// # Examples
2626 ///
2627 /// ```
2628 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_sub_signed(2), ", stringify!($SelfT), "::MAX);")]
2629 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_sub_signed(-2), 3);")]
2630 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).wrapping_sub_signed(-4), 1);")]
2631 /// ```
2632 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2633 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2634 #[must_use = "this returns the result of the operation, \
2635 without modifying the original"]
2636 #[inline]
2637 pub const fn wrapping_sub_signed(self, rhs: $SignedT) -> Self {
2638 self.wrapping_sub(rhs as Self)
2639 }
2640
2641 /// Wrapping (modular) multiplication. Computes `self *
2642 /// rhs`, wrapping around at the boundary of the type.
2643 ///
2644 /// # Examples
2645 ///
2646 /// Please note that this example is shared among integer types, which is why `u8` is used.
2647 ///
2648 /// ```
2649 /// assert_eq!(10u8.wrapping_mul(12), 120);
2650 /// assert_eq!(25u8.wrapping_mul(12), 44);
2651 /// ```
2652 #[stable(feature = "rust1", since = "1.0.0")]
2653 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2654 #[must_use = "this returns the result of the operation, \
2655 without modifying the original"]
2656 #[inline(always)]
2657 pub const fn wrapping_mul(self, rhs: Self) -> Self {
2658 intrinsics::wrapping_mul(self, rhs)
2659 }
2660
2661 /// Wrapping (modular) division. Computes `self / rhs`.
2662 ///
2663 /// Wrapped division on unsigned types is just normal division. There's
2664 /// no way wrapping could ever happen. This function exists so that all
2665 /// operations are accounted for in the wrapping operations.
2666 ///
2667 /// # Panics
2668 ///
2669 /// This function will panic if `rhs` is zero.
2670 ///
2671 /// # Examples
2672 ///
2673 /// ```
2674 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_div(10), 10);")]
2675 /// ```
2676 #[stable(feature = "num_wrapping", since = "1.2.0")]
2677 #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.52.0")]
2678 #[must_use = "this returns the result of the operation, \
2679 without modifying the original"]
2680 #[inline(always)]
2681 #[track_caller]
2682 pub const fn wrapping_div(self, rhs: Self) -> Self {
2683 self / rhs
2684 }
2685
2686 /// Wrapping Euclidean division. Computes `self.div_euclid(rhs)`.
2687 ///
2688 /// Wrapped division on unsigned types is just normal division. There's
2689 /// no way wrapping could ever happen. This function exists so that all
2690 /// operations are accounted for in the wrapping operations. Since, for
2691 /// the positive integers, all common definitions of division are equal,
2692 /// this is exactly equal to `self.wrapping_div(rhs)`.
2693 ///
2694 /// # Panics
2695 ///
2696 /// This function will panic if `rhs` is zero.
2697 ///
2698 /// # Examples
2699 ///
2700 /// ```
2701 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_div_euclid(10), 10);")]
2702 /// ```
2703 #[stable(feature = "euclidean_division", since = "1.38.0")]
2704 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
2705 #[must_use = "this returns the result of the operation, \
2706 without modifying the original"]
2707 #[inline(always)]
2708 #[track_caller]
2709 pub const fn wrapping_div_euclid(self, rhs: Self) -> Self {
2710 self / rhs
2711 }
2712
2713 /// Wrapping (modular) remainder. Computes `self % rhs`.
2714 ///
2715 /// Wrapped remainder calculation on unsigned types is just the regular
2716 /// remainder calculation. There's no way wrapping could ever happen.
2717 /// This function exists so that all operations are accounted for in the
2718 /// wrapping operations.
2719 ///
2720 /// # Panics
2721 ///
2722 /// This function will panic if `rhs` is zero.
2723 ///
2724 /// # Examples
2725 ///
2726 /// ```
2727 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_rem(10), 0);")]
2728 /// ```
2729 #[stable(feature = "num_wrapping", since = "1.2.0")]
2730 #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.52.0")]
2731 #[must_use = "this returns the result of the operation, \
2732 without modifying the original"]
2733 #[inline(always)]
2734 #[track_caller]
2735 pub const fn wrapping_rem(self, rhs: Self) -> Self {
2736 self % rhs
2737 }
2738
2739 /// Wrapping Euclidean modulo. Computes `self.rem_euclid(rhs)`.
2740 ///
2741 /// Wrapped modulo calculation on unsigned types is just the regular
2742 /// remainder calculation. There's no way wrapping could ever happen.
2743 /// This function exists so that all operations are accounted for in the
2744 /// wrapping operations. Since, for the positive integers, all common
2745 /// definitions of division are equal, this is exactly equal to
2746 /// `self.wrapping_rem(rhs)`.
2747 ///
2748 /// # Panics
2749 ///
2750 /// This function will panic if `rhs` is zero.
2751 ///
2752 /// # Examples
2753 ///
2754 /// ```
2755 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_rem_euclid(10), 0);")]
2756 /// ```
2757 #[stable(feature = "euclidean_division", since = "1.38.0")]
2758 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
2759 #[must_use = "this returns the result of the operation, \
2760 without modifying the original"]
2761 #[inline(always)]
2762 #[track_caller]
2763 pub const fn wrapping_rem_euclid(self, rhs: Self) -> Self {
2764 self % rhs
2765 }
2766
2767 /// Wrapping (modular) negation. Computes `-self`,
2768 /// wrapping around at the boundary of the type.
2769 ///
2770 /// Since unsigned types do not have negative equivalents
2771 /// all applications of this function will wrap (except for `-0`).
2772 /// For values smaller than the corresponding signed type's maximum
2773 /// the result is the same as casting the corresponding signed value.
2774 /// Any larger values are equivalent to `MAX + 1 - (val - MAX - 1)` where
2775 /// `MAX` is the corresponding signed type's maximum.
2776 ///
2777 /// # Examples
2778 ///
2779 /// ```
2780 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".wrapping_neg(), 0);")]
2781 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_neg(), 1);")]
2782 #[doc = concat!("assert_eq!(13_", stringify!($SelfT), ".wrapping_neg(), (!13) + 1);")]
2783 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_neg(), !(42 - 1));")]
2784 /// ```
2785 #[stable(feature = "num_wrapping", since = "1.2.0")]
2786 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2787 #[must_use = "this returns the result of the operation, \
2788 without modifying the original"]
2789 #[inline(always)]
2790 pub const fn wrapping_neg(self) -> Self {
2791 (0 as $SelfT).wrapping_sub(self)
2792 }
2793
2794 /// Panic-free bitwise shift-left; yields `self << mask(rhs)`,
2795 /// where `mask` removes any high-order bits of `rhs` that
2796 /// would cause the shift to exceed the bitwidth of the type.
2797 ///
2798 /// Beware that, unlike most other `wrapping_*` methods on integers, this
2799 /// does *not* give the same result as doing the shift in infinite precision
2800 /// then truncating as needed. The behaviour matches what shift instructions
2801 /// do on many processors, and is what the `<<` operator does when overflow
2802 /// checks are disabled, but numerically it's weird. Consider, instead,
2803 /// using [`Self::unbounded_shl`] which has nicer behaviour.
2804 ///
2805 /// Note that this is *not* the same as a rotate-left; the
2806 /// RHS of a wrapping shift-left is restricted to the range
2807 /// of the type, rather than the bits shifted out of the LHS
2808 /// being returned to the other end. The primitive integer
2809 /// types all implement a [`rotate_left`](Self::rotate_left) function,
2810 /// which may be what you want instead.
2811 ///
2812 /// # Examples
2813 ///
2814 /// ```
2815 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".wrapping_shl(7), 128);")]
2816 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(0), 0b101);")]
2817 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(1), 0b1010);")]
2818 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(2), 0b10100);")]
2819 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_shl(2), ", stringify!($SelfT), "::MAX - 3);")]
2820 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shl(", stringify!($BITS), "), 42);")]
2821 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shl(1).wrapping_shl(", stringify!($BITS_MINUS_ONE), "), 0);")]
2822 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".wrapping_shl(128), 1);")]
2823 #[doc = concat!("assert_eq!(5_", stringify!($SelfT), ".wrapping_shl(1025), 10);")]
2824 /// ```
2825 #[stable(feature = "num_wrapping", since = "1.2.0")]
2826 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2827 #[must_use = "this returns the result of the operation, \
2828 without modifying the original"]
2829 #[inline(always)]
2830 pub const fn wrapping_shl(self, rhs: u32) -> Self {
2831 // SAFETY: the masking by the bitsize of the type ensures that we do not shift
2832 // out of bounds
2833 unsafe {
2834 self.unchecked_shl(rhs & (Self::BITS - 1))
2835 }
2836 }
2837
2838 /// Panic-free bitwise shift-right; yields `self >> mask(rhs)`,
2839 /// where `mask` removes any high-order bits of `rhs` that
2840 /// would cause the shift to exceed the bitwidth of the type.
2841 ///
2842 /// Beware that, unlike most other `wrapping_*` methods on integers, this
2843 /// does *not* give the same result as doing the shift in infinite precision
2844 /// then truncating as needed. The behaviour matches what shift instructions
2845 /// do on many processors, and is what the `>>` operator does when overflow
2846 /// checks are disabled, but numerically it's weird. Consider, instead,
2847 /// using [`Self::unbounded_shr`] which has nicer behaviour.
2848 ///
2849 /// Note that this is *not* the same as a rotate-right; the
2850 /// RHS of a wrapping shift-right is restricted to the range
2851 /// of the type, rather than the bits shifted out of the LHS
2852 /// being returned to the other end. The primitive integer
2853 /// types all implement a [`rotate_right`](Self::rotate_right) function,
2854 /// which may be what you want instead.
2855 ///
2856 /// # Examples
2857 ///
2858 /// ```
2859 #[doc = concat!("assert_eq!(128_", stringify!($SelfT), ".wrapping_shr(7), 1);")]
2860 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(0), 0b1010);")]
2861 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(1), 0b101);")]
2862 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(2), 0b10);")]
2863 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_shr(1), ", stringify!($SignedT), "::MAX.cast_unsigned());")]
2864 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shr(", stringify!($BITS), "), 42);")]
2865 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shr(1).wrapping_shr(", stringify!($BITS_MINUS_ONE), "), 0);")]
2866 #[doc = concat!("assert_eq!(128_", stringify!($SelfT), ".wrapping_shr(128), 128);")]
2867 #[doc = concat!("assert_eq!(10_", stringify!($SelfT), ".wrapping_shr(1025), 5);")]
2868 /// ```
2869 #[stable(feature = "num_wrapping", since = "1.2.0")]
2870 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2871 #[must_use = "this returns the result of the operation, \
2872 without modifying the original"]
2873 #[inline(always)]
2874 pub const fn wrapping_shr(self, rhs: u32) -> Self {
2875 // SAFETY: the masking by the bitsize of the type ensures that we do not shift
2876 // out of bounds
2877 unsafe {
2878 self.unchecked_shr(rhs & (Self::BITS - 1))
2879 }
2880 }
2881
2882 /// Wrapping (modular) exponentiation. Computes `self.pow(exp)`,
2883 /// wrapping around at the boundary of the type.
2884 ///
2885 /// # Examples
2886 ///
2887 /// ```
2888 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".wrapping_pow(5), 243);")]
2889 /// assert_eq!(3u8.wrapping_pow(6), 217);
2890 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".wrapping_pow(0), 1);")]
2891 /// ```
2892 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2893 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2894 #[must_use = "this returns the result of the operation, \
2895 without modifying the original"]
2896 #[inline]
2897 pub const fn wrapping_pow(self, mut exp: u32) -> Self {
2898 if exp == 0 {
2899 return 1;
2900 }
2901 let mut base = self;
2902 let mut acc: Self = 1;
2903
2904 if intrinsics::is_val_statically_known(exp) {
2905 while exp > 1 {
2906 if (exp & 1) == 1 {
2907 acc = acc.wrapping_mul(base);
2908 }
2909 exp /= 2;
2910 base = base.wrapping_mul(base);
2911 }
2912
2913 // since exp!=0, finally the exp must be 1.
2914 // Deal with the final bit of the exponent separately, since
2915 // squaring the base afterwards is not necessary.
2916 acc.wrapping_mul(base)
2917 } else {
2918 // This is faster than the above when the exponent is not known
2919 // at compile time. We can't use the same code for the constant
2920 // exponent case because LLVM is currently unable to unroll
2921 // this loop.
2922 loop {
2923 if (exp & 1) == 1 {
2924 acc = acc.wrapping_mul(base);
2925 // since exp!=0, finally the exp must be 1.
2926 if exp == 1 {
2927 return acc;
2928 }
2929 }
2930 exp /= 2;
2931 base = base.wrapping_mul(base);
2932 }
2933 }
2934 }
2935
2936 /// Calculates `self` + `rhs`.
2937 ///
2938 /// Returns a tuple of the addition along with a boolean indicating
2939 /// whether an arithmetic overflow would occur. If an overflow would
2940 /// have occurred then the wrapped value is returned.
2941 ///
2942 /// # Examples
2943 ///
2944 /// ```
2945 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_add(2), (7, false));")]
2946 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.overflowing_add(1), (0, true));")]
2947 /// ```
2948 #[stable(feature = "wrapping", since = "1.7.0")]
2949 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2950 #[must_use = "this returns the result of the operation, \
2951 without modifying the original"]
2952 #[inline(always)]
2953 pub const fn overflowing_add(self, rhs: Self) -> (Self, bool) {
2954 let (a, b) = intrinsics::add_with_overflow(self as $ActualT, rhs as $ActualT);
2955 (a as Self, b)
2956 }
2957
2958 /// Calculates `self` + `rhs` + `carry` and returns a tuple containing
2959 /// the sum and the output carry (in that order).
2960 ///
2961 /// Performs "ternary addition" of two integer operands and a carry-in
2962 /// bit, and returns an output integer and a carry-out bit. This allows
2963 /// chaining together multiple additions to create a wider addition, and
2964 /// can be useful for bignum addition.
2965 ///
2966 #[doc = concat!("This can be thought of as a ", stringify!($BITS), "-bit \"full adder\", in the electronics sense.")]
2967 ///
2968 /// If the input carry is false, this method is equivalent to
2969 /// [`overflowing_add`](Self::overflowing_add), and the output carry is
2970 /// equal to the overflow flag. Note that although carry and overflow
2971 /// flags are similar for unsigned integers, they are different for
2972 /// signed integers.
2973 ///
2974 /// # Examples
2975 ///
2976 /// ```
2977 #[doc = concat!("// 3 MAX (a = 3 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")]
2978 #[doc = concat!("// + 5 7 (b = 5 × 2^", stringify!($BITS), " + 7)")]
2979 /// // ---------
2980 #[doc = concat!("// 9 6 (sum = 9 × 2^", stringify!($BITS), " + 6)")]
2981 ///
2982 #[doc = concat!("let (a1, a0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (3, ", stringify!($SelfT), "::MAX);")]
2983 #[doc = concat!("let (b1, b0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (5, 7);")]
2984 /// let carry0 = false;
2985 ///
2986 /// let (sum0, carry1) = a0.carrying_add(b0, carry0);
2987 /// assert_eq!(carry1, true);
2988 /// let (sum1, carry2) = a1.carrying_add(b1, carry1);
2989 /// assert_eq!(carry2, false);
2990 ///
2991 /// assert_eq!((sum1, sum0), (9, 6));
2992 /// ```
2993 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
2994 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
2995 #[must_use = "this returns the result of the operation, \
2996 without modifying the original"]
2997 #[inline]
2998 pub const fn carrying_add(self, rhs: Self, carry: bool) -> (Self, bool) {
2999 // note: longer-term this should be done via an intrinsic, but this has been shown
3000 // to generate optimal code for now, and LLVM doesn't have an equivalent intrinsic
3001 let (a, c1) = self.overflowing_add(rhs);
3002 let (b, c2) = a.overflowing_add(carry as $SelfT);
3003 // Ideally LLVM would know this is disjoint without us telling them,
3004 // but it doesn't <https://github.com/llvm/llvm-project/issues/118162>
3005 // SAFETY: Only one of `c1` and `c2` can be set.
3006 // For c1 to be set we need to have overflowed, but if we did then
3007 // `a` is at most `MAX-1`, which means that `c2` cannot possibly
3008 // overflow because it's adding at most `1` (since it came from `bool`)
3009 (b, unsafe { intrinsics::disjoint_bitor(c1, c2) })
3010 }
3011
3012 /// Calculates `self` + `rhs` with a signed `rhs`.
3013 ///
3014 /// Returns a tuple of the addition along with a boolean indicating
3015 /// whether an arithmetic overflow would occur. If an overflow would
3016 /// have occurred then the wrapped value is returned.
3017 ///
3018 /// # Examples
3019 ///
3020 /// ```
3021 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_add_signed(2), (3, false));")]
3022 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_add_signed(-2), (", stringify!($SelfT), "::MAX, true));")]
3023 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).overflowing_add_signed(4), (1, true));")]
3024 /// ```
3025 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
3026 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
3027 #[must_use = "this returns the result of the operation, \
3028 without modifying the original"]
3029 #[inline]
3030 pub const fn overflowing_add_signed(self, rhs: $SignedT) -> (Self, bool) {
3031 let (res, overflowed) = self.overflowing_add(rhs as Self);
3032 (res, overflowed ^ (rhs < 0))
3033 }
3034
3035 /// Calculates `self` - `rhs`.
3036 ///
3037 /// Returns a tuple of the subtraction along with a boolean indicating
3038 /// whether an arithmetic overflow would occur. If an overflow would
3039 /// have occurred then the wrapped value is returned.
3040 ///
3041 /// # Examples
3042 ///
3043 /// ```
3044 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_sub(2), (3, false));")]
3045 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".overflowing_sub(1), (", stringify!($SelfT), "::MAX, true));")]
3046 /// ```
3047 #[stable(feature = "wrapping", since = "1.7.0")]
3048 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3049 #[must_use = "this returns the result of the operation, \
3050 without modifying the original"]
3051 #[inline(always)]
3052 pub const fn overflowing_sub(self, rhs: Self) -> (Self, bool) {
3053 let (a, b) = intrinsics::sub_with_overflow(self as $ActualT, rhs as $ActualT);
3054 (a as Self, b)
3055 }
3056
3057 /// Calculates `self` − `rhs` − `borrow` and returns a tuple
3058 /// containing the difference and the output borrow.
3059 ///
3060 /// Performs "ternary subtraction" by subtracting both an integer
3061 /// operand and a borrow-in bit from `self`, and returns an output
3062 /// integer and a borrow-out bit. This allows chaining together multiple
3063 /// subtractions to create a wider subtraction, and can be useful for
3064 /// bignum subtraction.
3065 ///
3066 /// # Examples
3067 ///
3068 /// ```
3069 #[doc = concat!("// 9 6 (a = 9 × 2^", stringify!($BITS), " + 6)")]
3070 #[doc = concat!("// - 5 7 (b = 5 × 2^", stringify!($BITS), " + 7)")]
3071 /// // ---------
3072 #[doc = concat!("// 3 MAX (diff = 3 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")]
3073 ///
3074 #[doc = concat!("let (a1, a0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (9, 6);")]
3075 #[doc = concat!("let (b1, b0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (5, 7);")]
3076 /// let borrow0 = false;
3077 ///
3078 /// let (diff0, borrow1) = a0.borrowing_sub(b0, borrow0);
3079 /// assert_eq!(borrow1, true);
3080 /// let (diff1, borrow2) = a1.borrowing_sub(b1, borrow1);
3081 /// assert_eq!(borrow2, false);
3082 ///
3083 #[doc = concat!("assert_eq!((diff1, diff0), (3, ", stringify!($SelfT), "::MAX));")]
3084 /// ```
3085 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3086 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3087 #[must_use = "this returns the result of the operation, \
3088 without modifying the original"]
3089 #[inline]
3090 pub const fn borrowing_sub(self, rhs: Self, borrow: bool) -> (Self, bool) {
3091 // note: longer-term this should be done via an intrinsic, but this has been shown
3092 // to generate optimal code for now, and LLVM doesn't have an equivalent intrinsic
3093 let (a, c1) = self.overflowing_sub(rhs);
3094 let (b, c2) = a.overflowing_sub(borrow as $SelfT);
3095 // SAFETY: Only one of `c1` and `c2` can be set.
3096 // For c1 to be set we need to have underflowed, but if we did then
3097 // `a` is nonzero, which means that `c2` cannot possibly
3098 // underflow because it's subtracting at most `1` (since it came from `bool`)
3099 (b, unsafe { intrinsics::disjoint_bitor(c1, c2) })
3100 }
3101
3102 /// Calculates `self` - `rhs` with a signed `rhs`
3103 ///
3104 /// Returns a tuple of the subtraction along with a boolean indicating
3105 /// whether an arithmetic overflow would occur. If an overflow would
3106 /// have occurred then the wrapped value is returned.
3107 ///
3108 /// # Examples
3109 ///
3110 /// ```
3111 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_signed(2), (", stringify!($SelfT), "::MAX, true));")]
3112 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_signed(-2), (3, false));")]
3113 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).overflowing_sub_signed(-4), (1, true));")]
3114 /// ```
3115 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
3116 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
3117 #[must_use = "this returns the result of the operation, \
3118 without modifying the original"]
3119 #[inline]
3120 pub const fn overflowing_sub_signed(self, rhs: $SignedT) -> (Self, bool) {
3121 let (res, overflow) = self.overflowing_sub(rhs as Self);
3122
3123 (res, overflow ^ (rhs < 0))
3124 }
3125
3126 /// Computes the absolute difference between `self` and `other`.
3127 ///
3128 /// # Examples
3129 ///
3130 /// ```
3131 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".abs_diff(80), 20", stringify!($SelfT), ");")]
3132 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".abs_diff(110), 10", stringify!($SelfT), ");")]
3133 /// ```
3134 #[stable(feature = "int_abs_diff", since = "1.60.0")]
3135 #[rustc_const_stable(feature = "int_abs_diff", since = "1.60.0")]
3136 #[must_use = "this returns the result of the operation, \
3137 without modifying the original"]
3138 #[inline]
3139 pub const fn abs_diff(self, other: Self) -> Self {
3140 if size_of::<Self>() == 1 {
3141 // Trick LLVM into generating the psadbw instruction when SSE2
3142 // is available and this function is autovectorized for u8's.
3143 (self as i32).wrapping_sub(other as i32).unsigned_abs() as Self
3144 } else {
3145 if self < other {
3146 other - self
3147 } else {
3148 self - other
3149 }
3150 }
3151 }
3152
3153 /// Calculates the multiplication of `self` and `rhs`.
3154 ///
3155 /// Returns a tuple of the multiplication along with a boolean
3156 /// indicating whether an arithmetic overflow would occur. If an
3157 /// overflow would have occurred then the wrapped value is returned.
3158 ///
3159 /// If you want the *value* of the overflow, rather than just *whether*
3160 /// an overflow occurred, see [`Self::carrying_mul`].
3161 ///
3162 /// # Examples
3163 ///
3164 /// Please note that this example is shared among integer types, which is why `u32` is used.
3165 ///
3166 /// ```
3167 /// assert_eq!(5u32.overflowing_mul(2), (10, false));
3168 /// assert_eq!(1_000_000_000u32.overflowing_mul(10), (1410065408, true));
3169 /// ```
3170 #[stable(feature = "wrapping", since = "1.7.0")]
3171 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3172 #[must_use = "this returns the result of the operation, \
3173 without modifying the original"]
3174 #[inline(always)]
3175 pub const fn overflowing_mul(self, rhs: Self) -> (Self, bool) {
3176 let (a, b) = intrinsics::mul_with_overflow(self as $ActualT, rhs as $ActualT);
3177 (a as Self, b)
3178 }
3179
3180 /// Calculates the complete double-width product `self * rhs`.
3181 ///
3182 /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
3183 /// of the result as two separate values, in that order. As such,
3184 /// `a.widening_mul(b).0` produces the same result as `a.wrapping_mul(b)`.
3185 ///
3186 /// If you also need to add a value and carry to the wide result, then you want
3187 /// [`Self::carrying_mul_add`] instead.
3188 ///
3189 /// If you also need to add a carry to the wide result, then you want
3190 /// [`Self::carrying_mul`] instead.
3191 ///
3192 /// If you just want to know *whether* the multiplication overflowed, then you
3193 /// want [`Self::overflowing_mul`] instead.
3194 ///
3195 /// # Examples
3196 ///
3197 /// ```
3198 /// #![feature(widening_mul)]
3199 #[doc = concat!("assert_eq!(5_", stringify!($SelfT), ".widening_mul(7), (35, 0));")]
3200 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.widening_mul(", stringify!($SelfT), "::MAX), (1, ", stringify!($SelfT), "::MAX - 1));")]
3201 /// ```
3202 ///
3203 /// Compared to other `*_mul` methods:
3204 /// ```
3205 /// #![feature(widening_mul)]
3206 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::widening_mul(1 << ", stringify!($BITS_MINUS_ONE), ", 6), (0, 3));")]
3207 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::overflowing_mul(1 << ", stringify!($BITS_MINUS_ONE), ", 6), (0, true));")]
3208 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::wrapping_mul(1 << ", stringify!($BITS_MINUS_ONE), ", 6), 0);")]
3209 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::checked_mul(1 << ", stringify!($BITS_MINUS_ONE), ", 6), None);")]
3210 /// ```
3211 ///
3212 /// Please note that this example is shared among integer types, which is why `u32` is used.
3213 ///
3214 /// ```
3215 /// #![feature(widening_mul)]
3216 /// assert_eq!(5u32.widening_mul(2), (10, 0));
3217 /// assert_eq!(1_000_000_000u32.widening_mul(10), (1410065408, 2));
3218 /// ```
3219 #[unstable(feature = "widening_mul", issue = "152016")]
3220 #[rustc_const_unstable(feature = "widening_mul", issue = "152016")]
3221 #[must_use = "this returns the result of the operation, \
3222 without modifying the original"]
3223 #[inline]
3224 pub const fn widening_mul(self, rhs: Self) -> (Self, Self) {
3225 Self::carrying_mul_add(self, rhs, 0, 0)
3226 }
3227
3228 /// Calculates the "full multiplication" `self * rhs + carry`
3229 /// without the possibility to overflow.
3230 ///
3231 /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
3232 /// of the result as two separate values, in that order.
3233 ///
3234 /// Performs "long multiplication" which takes in an extra amount to add, and may return an
3235 /// additional amount of overflow. This allows for chaining together multiple
3236 /// multiplications to create "big integers" which represent larger values.
3237 ///
3238 /// If you also need to add a value, then use [`Self::carrying_mul_add`].
3239 ///
3240 /// # Examples
3241 ///
3242 /// Please note that this example is shared among integer types, which is why `u32` is used.
3243 ///
3244 /// ```
3245 /// assert_eq!(5u32.carrying_mul(2, 0), (10, 0));
3246 /// assert_eq!(5u32.carrying_mul(2, 10), (20, 0));
3247 /// assert_eq!(1_000_000_000u32.carrying_mul(10, 0), (1410065408, 2));
3248 /// assert_eq!(1_000_000_000u32.carrying_mul(10, 10), (1410065418, 2));
3249 #[doc = concat!("assert_eq!(",
3250 stringify!($SelfT), "::MAX.carrying_mul(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
3251 "(0, ", stringify!($SelfT), "::MAX));"
3252 )]
3253 /// ```
3254 ///
3255 /// This is the core operation needed for scalar multiplication when
3256 /// implementing it for wider-than-native types.
3257 ///
3258 /// ```
3259 /// fn scalar_mul_eq(little_endian_digits: &mut Vec<u16>, multiplicand: u16) {
3260 /// let mut carry = 0;
3261 /// for d in little_endian_digits.iter_mut() {
3262 /// (*d, carry) = d.carrying_mul(multiplicand, carry);
3263 /// }
3264 /// if carry != 0 {
3265 /// little_endian_digits.push(carry);
3266 /// }
3267 /// }
3268 ///
3269 /// let mut v = vec![10, 20];
3270 /// scalar_mul_eq(&mut v, 3);
3271 /// assert_eq!(v, [30, 60]);
3272 ///
3273 /// assert_eq!(0x87654321_u64 * 0xFEED, 0x86D3D159E38D);
3274 /// let mut v = vec![0x4321, 0x8765];
3275 /// scalar_mul_eq(&mut v, 0xFEED);
3276 /// assert_eq!(v, [0xE38D, 0xD159, 0x86D3]);
3277 /// ```
3278 ///
3279 /// If `carry` is zero, this is similar to [`overflowing_mul`](Self::overflowing_mul),
3280 /// except that it gives the value of the overflow instead of just whether one happened:
3281 ///
3282 /// ```
3283 /// # #![allow(unused_features)]
3284 /// #![feature(const_unsigned_bigint_helpers)]
3285 /// let r = u8::carrying_mul(7, 13, 0);
3286 /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(7, 13));
3287 /// let r = u8::carrying_mul(13, 42, 0);
3288 /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(13, 42));
3289 /// ```
3290 ///
3291 /// The value of the first field in the returned tuple matches what you'd get
3292 /// by combining the [`wrapping_mul`](Self::wrapping_mul) and
3293 /// [`wrapping_add`](Self::wrapping_add) methods:
3294 ///
3295 /// ```
3296 /// # #![allow(unused_features)]
3297 /// #![feature(const_unsigned_bigint_helpers)]
3298 /// assert_eq!(
3299 /// 789_u16.carrying_mul(456, 123).0,
3300 /// 789_u16.wrapping_mul(456).wrapping_add(123),
3301 /// );
3302 /// ```
3303 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3304 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3305 #[must_use = "this returns the result of the operation, \
3306 without modifying the original"]
3307 #[inline]
3308 pub const fn carrying_mul(self, rhs: Self, carry: Self) -> (Self, Self) {
3309 Self::carrying_mul_add(self, rhs, carry, 0)
3310 }
3311
3312 /// Calculates the "full multiplication" `self * rhs + carry + add`.
3313 ///
3314 /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
3315 /// of the result as two separate values, in that order.
3316 ///
3317 /// This cannot overflow, as the double-width result has exactly enough
3318 /// space for the largest possible result. This is equivalent to how, in
3319 /// decimal, 9 × 9 + 9 + 9 = 81 + 18 = 99 = 9×10⁰ + 9×10¹ = 10² - 1.
3320 ///
3321 /// Performs "long multiplication" which takes in an extra amount to add, and may return an
3322 /// additional amount of overflow. This allows for chaining together multiple
3323 /// multiplications to create "big integers" which represent larger values.
3324 ///
3325 /// If you don't need the `add` part, then you can use [`Self::carrying_mul`] instead.
3326 ///
3327 /// # Examples
3328 ///
3329 /// Please note that this example is shared between integer types,
3330 /// which explains why `u32` is used here.
3331 ///
3332 /// ```
3333 /// assert_eq!(5u32.carrying_mul_add(2, 0, 0), (10, 0));
3334 /// assert_eq!(5u32.carrying_mul_add(2, 10, 10), (30, 0));
3335 /// assert_eq!(1_000_000_000u32.carrying_mul_add(10, 0, 0), (1410065408, 2));
3336 /// assert_eq!(1_000_000_000u32.carrying_mul_add(10, 10, 10), (1410065428, 2));
3337 #[doc = concat!("assert_eq!(",
3338 stringify!($SelfT), "::MAX.carrying_mul_add(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
3339 "(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX));"
3340 )]
3341 /// ```
3342 ///
3343 /// This is the core per-digit operation for "grade school" O(n²) multiplication.
3344 ///
3345 /// Please note that this example is shared between integer types,
3346 /// using `u8` for simplicity of the demonstration.
3347 ///
3348 /// ```
3349 /// fn quadratic_mul<const N: usize>(a: [u8; N], b: [u8; N]) -> [u8; N] {
3350 /// let mut out = [0; N];
3351 /// for j in 0..N {
3352 /// let mut carry = 0;
3353 /// for i in 0..(N - j) {
3354 /// (out[j + i], carry) = u8::carrying_mul_add(a[i], b[j], out[j + i], carry);
3355 /// }
3356 /// }
3357 /// out
3358 /// }
3359 ///
3360 /// // -1 * -1 == 1
3361 /// assert_eq!(quadratic_mul([0xFF; 3], [0xFF; 3]), [1, 0, 0]);
3362 ///
3363 /// assert_eq!(u32::wrapping_mul(0x9e3779b9, 0x7f4a7c15), 0xcffc982d);
3364 /// assert_eq!(
3365 /// quadratic_mul(u32::to_le_bytes(0x9e3779b9), u32::to_le_bytes(0x7f4a7c15)),
3366 /// u32::to_le_bytes(0xcffc982d)
3367 /// );
3368 /// ```
3369 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3370 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3371 #[must_use = "this returns the result of the operation, \
3372 without modifying the original"]
3373 #[inline]
3374 pub const fn carrying_mul_add(self, rhs: Self, carry: Self, add: Self) -> (Self, Self) {
3375 intrinsics::carrying_mul_add(self, rhs, carry, add)
3376 }
3377
3378 /// Calculates the divisor when `self` is divided by `rhs`.
3379 ///
3380 /// Returns a tuple of the divisor along with a boolean indicating
3381 /// whether an arithmetic overflow would occur. Note that for unsigned
3382 /// integers overflow never occurs, so the second value is always
3383 /// `false`.
3384 ///
3385 /// # Panics
3386 ///
3387 /// This function will panic if `rhs` is zero.
3388 ///
3389 /// # Examples
3390 ///
3391 /// ```
3392 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_div(2), (2, false));")]
3393 /// ```
3394 #[inline(always)]
3395 #[stable(feature = "wrapping", since = "1.7.0")]
3396 #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
3397 #[must_use = "this returns the result of the operation, \
3398 without modifying the original"]
3399 #[track_caller]
3400 pub const fn overflowing_div(self, rhs: Self) -> (Self, bool) {
3401 (self / rhs, false)
3402 }
3403
3404 /// Calculates the quotient of Euclidean division `self.div_euclid(rhs)`.
3405 ///
3406 /// Returns a tuple of the divisor along with a boolean indicating
3407 /// whether an arithmetic overflow would occur. Note that for unsigned
3408 /// integers overflow never occurs, so the second value is always
3409 /// `false`.
3410 /// Since, for the positive integers, all common
3411 /// definitions of division are equal, this
3412 /// is exactly equal to `self.overflowing_div(rhs)`.
3413 ///
3414 /// # Panics
3415 ///
3416 /// This function will panic if `rhs` is zero.
3417 ///
3418 /// # Examples
3419 ///
3420 /// ```
3421 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_div_euclid(2), (2, false));")]
3422 /// ```
3423 #[inline(always)]
3424 #[stable(feature = "euclidean_division", since = "1.38.0")]
3425 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3426 #[must_use = "this returns the result of the operation, \
3427 without modifying the original"]
3428 #[track_caller]
3429 pub const fn overflowing_div_euclid(self, rhs: Self) -> (Self, bool) {
3430 (self / rhs, false)
3431 }
3432
3433 /// Calculates the remainder when `self` is divided by `rhs`.
3434 ///
3435 /// Returns a tuple of the remainder after dividing along with a boolean
3436 /// indicating whether an arithmetic overflow would occur. Note that for
3437 /// unsigned integers overflow never occurs, so the second value is
3438 /// always `false`.
3439 ///
3440 /// # Panics
3441 ///
3442 /// This function will panic if `rhs` is zero.
3443 ///
3444 /// # Examples
3445 ///
3446 /// ```
3447 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_rem(2), (1, false));")]
3448 /// ```
3449 #[inline(always)]
3450 #[stable(feature = "wrapping", since = "1.7.0")]
3451 #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
3452 #[must_use = "this returns the result of the operation, \
3453 without modifying the original"]
3454 #[track_caller]
3455 pub const fn overflowing_rem(self, rhs: Self) -> (Self, bool) {
3456 (self % rhs, false)
3457 }
3458
3459 /// Calculates the remainder `self.rem_euclid(rhs)` as if by Euclidean division.
3460 ///
3461 /// Returns a tuple of the modulo after dividing along with a boolean
3462 /// indicating whether an arithmetic overflow would occur. Note that for
3463 /// unsigned integers overflow never occurs, so the second value is
3464 /// always `false`.
3465 /// Since, for the positive integers, all common
3466 /// definitions of division are equal, this operation
3467 /// is exactly equal to `self.overflowing_rem(rhs)`.
3468 ///
3469 /// # Panics
3470 ///
3471 /// This function will panic if `rhs` is zero.
3472 ///
3473 /// # Examples
3474 ///
3475 /// ```
3476 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_rem_euclid(2), (1, false));")]
3477 /// ```
3478 #[inline(always)]
3479 #[stable(feature = "euclidean_division", since = "1.38.0")]
3480 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3481 #[must_use = "this returns the result of the operation, \
3482 without modifying the original"]
3483 #[track_caller]
3484 pub const fn overflowing_rem_euclid(self, rhs: Self) -> (Self, bool) {
3485 (self % rhs, false)
3486 }
3487
3488 /// Negates self in an overflowing fashion.
3489 ///
3490 /// Returns `!self + 1` using wrapping operations to return the value
3491 /// that represents the negation of this unsigned value. Note that for
3492 /// positive unsigned values overflow always occurs, but negating 0 does
3493 /// not overflow.
3494 ///
3495 /// # Examples
3496 ///
3497 /// ```
3498 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".overflowing_neg(), (0, false));")]
3499 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".overflowing_neg(), (-2i32 as ", stringify!($SelfT), ", true));")]
3500 /// ```
3501 #[inline(always)]
3502 #[stable(feature = "wrapping", since = "1.7.0")]
3503 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3504 #[must_use = "this returns the result of the operation, \
3505 without modifying the original"]
3506 pub const fn overflowing_neg(self) -> (Self, bool) {
3507 ((!self).wrapping_add(1), self != 0)
3508 }
3509
3510 /// Shifts self left by `rhs` bits.
3511 ///
3512 /// Returns a tuple of the shifted version of self along with a boolean
3513 /// indicating whether the shift value was larger than or equal to the
3514 /// number of bits. If the shift value is too large, then value is
3515 /// masked (N-1) where N is the number of bits, and this value is then
3516 /// used to perform the shift.
3517 ///
3518 /// # Examples
3519 ///
3520 /// ```
3521 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".overflowing_shl(4), (0x10, false));")]
3522 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".overflowing_shl(132), (0x10, true));")]
3523 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shl(", stringify!($BITS_MINUS_ONE), "), (0, false));")]
3524 /// ```
3525 #[stable(feature = "wrapping", since = "1.7.0")]
3526 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3527 #[must_use = "this returns the result of the operation, \
3528 without modifying the original"]
3529 #[inline(always)]
3530 pub const fn overflowing_shl(self, rhs: u32) -> (Self, bool) {
3531 (self.wrapping_shl(rhs), rhs >= Self::BITS)
3532 }
3533
3534 /// Shifts self right by `rhs` bits.
3535 ///
3536 /// Returns a tuple of the shifted version of self along with a boolean
3537 /// indicating whether the shift value was larger than or equal to the
3538 /// number of bits. If the shift value is too large, then value is
3539 /// masked (N-1) where N is the number of bits, and this value is then
3540 /// used to perform the shift.
3541 ///
3542 /// # Examples
3543 ///
3544 /// ```
3545 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shr(4), (0x1, false));")]
3546 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shr(132), (0x1, true));")]
3547 /// ```
3548 #[stable(feature = "wrapping", since = "1.7.0")]
3549 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3550 #[must_use = "this returns the result of the operation, \
3551 without modifying the original"]
3552 #[inline(always)]
3553 pub const fn overflowing_shr(self, rhs: u32) -> (Self, bool) {
3554 (self.wrapping_shr(rhs), rhs >= Self::BITS)
3555 }
3556
3557 /// Raises self to the power of `exp`, using exponentiation by squaring.
3558 ///
3559 /// Returns a tuple of the exponentiation along with a bool indicating
3560 /// whether an overflow happened.
3561 ///
3562 /// # Examples
3563 ///
3564 /// ```
3565 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".overflowing_pow(5), (243, false));")]
3566 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".overflowing_pow(0), (1, false));")]
3567 /// assert_eq!(3u8.overflowing_pow(6), (217, true));
3568 /// ```
3569 #[stable(feature = "no_panic_pow", since = "1.34.0")]
3570 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3571 #[must_use = "this returns the result of the operation, \
3572 without modifying the original"]
3573 #[inline]
3574 pub const fn overflowing_pow(self, mut exp: u32) -> (Self, bool) {
3575 if exp == 0{
3576 return (1,false);
3577 }
3578 let mut base = self;
3579 let mut acc: Self = 1;
3580 let mut overflown = false;
3581 // Scratch space for storing results of overflowing_mul.
3582 let mut r;
3583
3584 loop {
3585 if (exp & 1) == 1 {
3586 r = acc.overflowing_mul(base);
3587 // since exp!=0, finally the exp must be 1.
3588 if exp == 1 {
3589 r.1 |= overflown;
3590 return r;
3591 }
3592 acc = r.0;
3593 overflown |= r.1;
3594 }
3595 exp /= 2;
3596 r = base.overflowing_mul(base);
3597 base = r.0;
3598 overflown |= r.1;
3599 }
3600 }
3601
3602 /// Raises self to the power of `exp`, using exponentiation by squaring.
3603 ///
3604 /// # Examples
3605 ///
3606 /// ```
3607 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".pow(5), 32);")]
3608 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".pow(0), 1);")]
3609 /// ```
3610 #[stable(feature = "rust1", since = "1.0.0")]
3611 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3612 #[must_use = "this returns the result of the operation, \
3613 without modifying the original"]
3614 #[inline]
3615 #[rustc_inherit_overflow_checks]
3616 pub const fn pow(self, mut exp: u32) -> Self {
3617 if exp == 0 {
3618 return 1;
3619 }
3620 let mut base = self;
3621 let mut acc = 1;
3622
3623 if intrinsics::is_val_statically_known(exp) {
3624 while exp > 1 {
3625 if (exp & 1) == 1 {
3626 acc = acc * base;
3627 }
3628 exp /= 2;
3629 base = base * base;
3630 }
3631
3632 // since exp!=0, finally the exp must be 1.
3633 // Deal with the final bit of the exponent separately, since
3634 // squaring the base afterwards is not necessary and may cause a
3635 // needless overflow.
3636 acc * base
3637 } else {
3638 // This is faster than the above when the exponent is not known
3639 // at compile time. We can't use the same code for the constant
3640 // exponent case because LLVM is currently unable to unroll
3641 // this loop.
3642 loop {
3643 if (exp & 1) == 1 {
3644 acc = acc * base;
3645 // since exp!=0, finally the exp must be 1.
3646 if exp == 1 {
3647 return acc;
3648 }
3649 }
3650 exp /= 2;
3651 base = base * base;
3652 }
3653 }
3654 }
3655
3656 /// Returns the square root of the number, rounded down.
3657 ///
3658 /// # Examples
3659 ///
3660 /// ```
3661 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".isqrt(), 3);")]
3662 /// ```
3663 #[stable(feature = "isqrt", since = "1.84.0")]
3664 #[rustc_const_stable(feature = "isqrt", since = "1.84.0")]
3665 #[must_use = "this returns the result of the operation, \
3666 without modifying the original"]
3667 #[inline]
3668 pub const fn isqrt(self) -> Self {
3669 let result = imp::int_sqrt::$ActualT(self as $ActualT) as Self;
3670
3671 // Inform the optimizer what the range of outputs is. If testing
3672 // `core` crashes with no panic message and a `num::int_sqrt::u*`
3673 // test failed, it's because your edits caused these assertions or
3674 // the assertions in `fn isqrt` of `nonzero.rs` to become false.
3675 //
3676 // SAFETY: Integer square root is a monotonically nondecreasing
3677 // function, which means that increasing the input will never
3678 // cause the output to decrease. Thus, since the input for unsigned
3679 // integers is bounded by `[0, <$ActualT>::MAX]`, sqrt(n) will be
3680 // bounded by `[sqrt(0), sqrt(<$ActualT>::MAX)]` and bounding the
3681 // input by `[1, <$ActualT>::MAX]` bounds sqrt(n) by
3682 // `[sqrt(1), sqrt(<$ActualT>::MAX)]`.
3683 unsafe {
3684 const MAX_RESULT: $SelfT = imp::int_sqrt::$ActualT(<$ActualT>::MAX) as $SelfT;
3685 crate::hint::assert_unchecked(result <= MAX_RESULT)
3686 }
3687
3688 if self >= 1 {
3689 // SAFETY: The above statements about monotonicity also apply here.
3690 // Since the input in this branch is bounded by `[1, <$ActualT>::MAX]`,
3691 // sqrt(n) is bounded by `[sqrt(1), sqrt(<$ActualT>::MAX)]`, and
3692 // `sqrt(1) == 1`.
3693 unsafe { crate::hint::assert_unchecked(result >= 1) }
3694 }
3695
3696 // SAFETY: the isqrt implementation returns the square root and rounds down,
3697 // meaning `result * result <= self`. This implies `result <= self`.
3698 // The compiler needs both to optimize for both.
3699 // `result * result <= self` implies the multiplication will not overflow.
3700 unsafe {
3701 crate::hint::assert_unchecked(result.unchecked_mul(result) <= self);
3702 crate::hint::assert_unchecked(result <= self);
3703 }
3704
3705 result
3706 }
3707
3708 /// Performs Euclidean division.
3709 ///
3710 /// Since, for the positive integers, all common
3711 /// definitions of division are equal, this
3712 /// is exactly equal to `self / rhs`.
3713 ///
3714 /// # Panics
3715 ///
3716 /// This function will panic if `rhs` is zero.
3717 ///
3718 /// # Examples
3719 ///
3720 /// ```
3721 #[doc = concat!("assert_eq!(7", stringify!($SelfT), ".div_euclid(4), 1); // or any other integer type")]
3722 /// ```
3723 #[stable(feature = "euclidean_division", since = "1.38.0")]
3724 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3725 #[must_use = "this returns the result of the operation, \
3726 without modifying the original"]
3727 #[inline(always)]
3728 #[track_caller]
3729 pub const fn div_euclid(self, rhs: Self) -> Self {
3730 self / rhs
3731 }
3732
3733
3734 /// Calculates the least remainder of `self` when divided by
3735 /// `rhs`.
3736 ///
3737 /// Since, for the positive integers, all common
3738 /// definitions of division are equal, this
3739 /// is exactly equal to `self % rhs`.
3740 ///
3741 /// # Panics
3742 ///
3743 /// This function will panic if `rhs` is zero.
3744 ///
3745 /// # Examples
3746 ///
3747 /// ```
3748 #[doc = concat!("assert_eq!(7", stringify!($SelfT), ".rem_euclid(4), 3); // or any other integer type")]
3749 /// ```
3750 #[doc(alias = "modulo", alias = "mod")]
3751 #[stable(feature = "euclidean_division", since = "1.38.0")]
3752 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3753 #[must_use = "this returns the result of the operation, \
3754 without modifying the original"]
3755 #[inline(always)]
3756 #[track_caller]
3757 pub const fn rem_euclid(self, rhs: Self) -> Self {
3758 self % rhs
3759 }
3760
3761 /// Calculates the quotient of `self` and `rhs`, rounding the result towards negative infinity.
3762 ///
3763 /// This is the same as performing `self / rhs` for all unsigned integers.
3764 ///
3765 /// # Panics
3766 ///
3767 /// This function will panic if `rhs` is zero.
3768 ///
3769 /// # Examples
3770 ///
3771 /// ```
3772 /// #![feature(int_roundings)]
3773 #[doc = concat!("assert_eq!(7_", stringify!($SelfT), ".div_floor(4), 1);")]
3774 /// ```
3775 #[unstable(feature = "int_roundings", issue = "88581")]
3776 #[must_use = "this returns the result of the operation, \
3777 without modifying the original"]
3778 #[inline(always)]
3779 #[track_caller]
3780 pub const fn div_floor(self, rhs: Self) -> Self {
3781 self / rhs
3782 }
3783
3784 /// Calculates the quotient of `self` and `rhs`, rounding the result towards positive infinity.
3785 ///
3786 /// # Panics
3787 ///
3788 /// This function will panic if `rhs` is zero.
3789 ///
3790 /// # Examples
3791 ///
3792 /// ```
3793 #[doc = concat!("assert_eq!(7_", stringify!($SelfT), ".div_ceil(4), 2);")]
3794 /// ```
3795 #[stable(feature = "int_roundings1", since = "1.73.0")]
3796 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3797 #[must_use = "this returns the result of the operation, \
3798 without modifying the original"]
3799 #[inline]
3800 #[track_caller]
3801 pub const fn div_ceil(self, rhs: Self) -> Self {
3802 let d = self / rhs;
3803 let r = self % rhs;
3804 if r > 0 {
3805 d + 1
3806 } else {
3807 d
3808 }
3809 }
3810
3811 /// Calculates the smallest value greater than or equal to `self` that
3812 /// is a multiple of `rhs`.
3813 ///
3814 /// # Panics
3815 ///
3816 /// This function will panic if `rhs` is zero.
3817 ///
3818 /// ## Overflow behavior
3819 ///
3820 /// On overflow, this function will panic if overflow checks are enabled (default in debug
3821 /// mode) and wrap if overflow checks are disabled (default in release mode).
3822 ///
3823 /// # Examples
3824 ///
3825 /// ```
3826 #[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".next_multiple_of(8), 16);")]
3827 #[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".next_multiple_of(8), 24);")]
3828 /// ```
3829 #[stable(feature = "int_roundings1", since = "1.73.0")]
3830 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3831 #[must_use = "this returns the result of the operation, \
3832 without modifying the original"]
3833 #[inline]
3834 #[rustc_inherit_overflow_checks]
3835 pub const fn next_multiple_of(self, rhs: Self) -> Self {
3836 match self % rhs {
3837 0 => self,
3838 r => self + (rhs - r)
3839 }
3840 }
3841
3842 /// Calculates the smallest value greater than or equal to `self` that
3843 /// is a multiple of `rhs`. Returns `None` if `rhs` is zero or the
3844 /// operation would result in overflow.
3845 ///
3846 /// # Examples
3847 ///
3848 /// ```
3849 #[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".checked_next_multiple_of(8), Some(16));")]
3850 #[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".checked_next_multiple_of(8), Some(24));")]
3851 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".checked_next_multiple_of(0), None);")]
3852 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_next_multiple_of(2), None);")]
3853 /// ```
3854 #[stable(feature = "int_roundings1", since = "1.73.0")]
3855 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3856 #[must_use = "this returns the result of the operation, \
3857 without modifying the original"]
3858 #[inline]
3859 pub const fn checked_next_multiple_of(self, rhs: Self) -> Option<Self> {
3860 match try_opt!(self.checked_rem(rhs)) {
3861 0 => Some(self),
3862 // rhs - r cannot overflow because r is smaller than rhs
3863 r => self.checked_add(rhs - r)
3864 }
3865 }
3866
3867 /// Returns `true` if `self` is an integer multiple of `rhs`, and false otherwise.
3868 ///
3869 /// This function is equivalent to `self % rhs == 0`, except that it will not panic
3870 /// for `rhs == 0`. Instead, `0.is_multiple_of(0) == true`, and for any non-zero `n`,
3871 /// `n.is_multiple_of(0) == false`.
3872 ///
3873 /// # Examples
3874 ///
3875 /// ```
3876 #[doc = concat!("assert!(6_", stringify!($SelfT), ".is_multiple_of(2));")]
3877 #[doc = concat!("assert!(!5_", stringify!($SelfT), ".is_multiple_of(2));")]
3878 ///
3879 #[doc = concat!("assert!(0_", stringify!($SelfT), ".is_multiple_of(0));")]
3880 #[doc = concat!("assert!(!6_", stringify!($SelfT), ".is_multiple_of(0));")]
3881 /// ```
3882 #[stable(feature = "unsigned_is_multiple_of", since = "1.87.0")]
3883 #[rustc_const_stable(feature = "unsigned_is_multiple_of", since = "1.87.0")]
3884 #[must_use]
3885 #[inline]
3886 pub const fn is_multiple_of(self, rhs: Self) -> bool {
3887 match rhs {
3888 0 => self == 0,
3889 _ => self % rhs == 0,
3890 }
3891 }
3892
3893 /// Returns `true` if and only if `self == 2^k` for some unsigned integer `k`.
3894 ///
3895 /// # Examples
3896 ///
3897 /// ```
3898 #[doc = concat!("assert!(16", stringify!($SelfT), ".is_power_of_two());")]
3899 #[doc = concat!("assert!(!10", stringify!($SelfT), ".is_power_of_two());")]
3900 /// ```
3901 #[must_use]
3902 #[stable(feature = "rust1", since = "1.0.0")]
3903 #[rustc_const_stable(feature = "const_is_power_of_two", since = "1.32.0")]
3904 #[inline(always)]
3905 pub const fn is_power_of_two(self) -> bool {
3906 self.count_ones() == 1
3907 }
3908
3909 // Returns one less than next power of two.
3910 // (For 8u8 next power of two is 8u8 and for 6u8 it is 8u8)
3911 //
3912 // 8u8.one_less_than_next_power_of_two() == 7
3913 // 6u8.one_less_than_next_power_of_two() == 7
3914 //
3915 // This method cannot overflow, as in the `next_power_of_two`
3916 // overflow cases it instead ends up returning the maximum value
3917 // of the type, and can return 0 for 0.
3918 #[inline]
3919 const fn one_less_than_next_power_of_two(self) -> Self {
3920 if self <= 1 { return 0; }
3921
3922 let p = self - 1;
3923 // SAFETY: Because `p > 0`, it cannot consist entirely of leading zeros.
3924 // That means the shift is always in-bounds, and some processors
3925 // (such as intel pre-haswell) have more efficient ctlz
3926 // intrinsics when the argument is non-zero.
3927 let z = unsafe { intrinsics::ctlz_nonzero(p) };
3928 <$SelfT>::MAX >> z
3929 }
3930
3931 /// Returns the smallest power of two greater than or equal to `self`.
3932 ///
3933 /// When return value overflows (i.e., `self > (1 << (N-1))` for type
3934 /// `uN`), it panics in debug mode and the return value is wrapped to 0 in
3935 /// release mode (the only situation in which this method can return 0).
3936 ///
3937 /// # Examples
3938 ///
3939 /// ```
3940 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".next_power_of_two(), 2);")]
3941 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".next_power_of_two(), 4);")]
3942 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".next_power_of_two(), 1);")]
3943 /// ```
3944 #[stable(feature = "rust1", since = "1.0.0")]
3945 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3946 #[must_use = "this returns the result of the operation, \
3947 without modifying the original"]
3948 #[inline]
3949 #[rustc_inherit_overflow_checks]
3950 pub const fn next_power_of_two(self) -> Self {
3951 self.one_less_than_next_power_of_two() + 1
3952 }
3953
3954 /// Returns the smallest power of two greater than or equal to `self`. If
3955 /// the next power of two is greater than the type's maximum value,
3956 /// `None` is returned, otherwise the power of two is wrapped in `Some`.
3957 ///
3958 /// # Examples
3959 ///
3960 /// ```
3961 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_next_power_of_two(), Some(2));")]
3962 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".checked_next_power_of_two(), Some(4));")]
3963 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_next_power_of_two(), None);")]
3964 /// ```
3965 #[inline]
3966 #[stable(feature = "rust1", since = "1.0.0")]
3967 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3968 #[must_use = "this returns the result of the operation, \
3969 without modifying the original"]
3970 pub const fn checked_next_power_of_two(self) -> Option<Self> {
3971 self.one_less_than_next_power_of_two().checked_add(1)
3972 }
3973
3974 /// Returns the smallest power of two greater than or equal to `n`. If
3975 /// the next power of two is greater than the type's maximum value,
3976 /// the return value is wrapped to `0`.
3977 ///
3978 /// # Examples
3979 ///
3980 /// ```
3981 /// #![feature(wrapping_next_power_of_two)]
3982 ///
3983 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".wrapping_next_power_of_two(), 2);")]
3984 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".wrapping_next_power_of_two(), 4);")]
3985 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_next_power_of_two(), 0);")]
3986 /// ```
3987 #[inline]
3988 #[unstable(feature = "wrapping_next_power_of_two", issue = "32463",
3989 reason = "needs decision on wrapping behavior")]
3990 #[must_use = "this returns the result of the operation, \
3991 without modifying the original"]
3992 pub const fn wrapping_next_power_of_two(self) -> Self {
3993 self.one_less_than_next_power_of_two().wrapping_add(1)
3994 }
3995
3996 /// Returns the memory representation of this integer as a byte array in
3997 /// big-endian (network) byte order.
3998 ///
3999 #[doc = $to_xe_bytes_doc]
4000 ///
4001 /// # Examples
4002 ///
4003 /// ```
4004 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_be_bytes();")]
4005 #[doc = concat!("assert_eq!(bytes, ", $be_bytes, ");")]
4006 /// ```
4007 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4008 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4009 #[must_use = "this returns the result of the operation, \
4010 without modifying the original"]
4011 #[inline]
4012 pub const fn to_be_bytes(self) -> [u8; size_of::<Self>()] {
4013 self.to_be().to_ne_bytes()
4014 }
4015
4016 /// Returns the memory representation of this integer as a byte array in
4017 /// little-endian byte order.
4018 ///
4019 #[doc = $to_xe_bytes_doc]
4020 ///
4021 /// # Examples
4022 ///
4023 /// ```
4024 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_le_bytes();")]
4025 #[doc = concat!("assert_eq!(bytes, ", $le_bytes, ");")]
4026 /// ```
4027 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4028 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4029 #[must_use = "this returns the result of the operation, \
4030 without modifying the original"]
4031 #[inline]
4032 pub const fn to_le_bytes(self) -> [u8; size_of::<Self>()] {
4033 self.to_le().to_ne_bytes()
4034 }
4035
4036 /// Returns the memory representation of this integer as a byte array in
4037 /// native byte order.
4038 ///
4039 /// As the target platform's native endianness is used, portable code
4040 /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate,
4041 /// instead.
4042 ///
4043 #[doc = $to_xe_bytes_doc]
4044 ///
4045 /// [`to_be_bytes`]: Self::to_be_bytes
4046 /// [`to_le_bytes`]: Self::to_le_bytes
4047 ///
4048 /// # Examples
4049 ///
4050 /// ```
4051 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_ne_bytes();")]
4052 /// assert_eq!(
4053 /// bytes,
4054 /// if cfg!(target_endian = "big") {
4055 #[doc = concat!(" ", $be_bytes)]
4056 /// } else {
4057 #[doc = concat!(" ", $le_bytes)]
4058 /// }
4059 /// );
4060 /// ```
4061 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4062 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4063 #[must_use = "this returns the result of the operation, \
4064 without modifying the original"]
4065 #[allow(unnecessary_transmutes)]
4066 // SAFETY: const sound because integers are plain old datatypes so we can always
4067 // transmute them to arrays of bytes
4068 #[inline]
4069 pub const fn to_ne_bytes(self) -> [u8; size_of::<Self>()] {
4070 // SAFETY: integers are plain old datatypes so we can always transmute them to
4071 // arrays of bytes
4072 unsafe { mem::transmute(self) }
4073 }
4074
4075 /// Creates a native endian integer value from its representation
4076 /// as a byte array in big endian.
4077 ///
4078 #[doc = $from_xe_bytes_doc]
4079 ///
4080 /// # Examples
4081 ///
4082 /// ```
4083 #[doc = concat!("let value = ", stringify!($SelfT), "::from_be_bytes(", $be_bytes, ");")]
4084 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4085 /// ```
4086 ///
4087 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4088 ///
4089 /// ```
4090 #[doc = concat!("fn read_be_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4091 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4092 /// *input = rest;
4093 #[doc = concat!(" ", stringify!($SelfT), "::from_be_bytes(int_bytes.try_into().unwrap())")]
4094 /// }
4095 /// ```
4096 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4097 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4098 #[must_use]
4099 #[inline]
4100 pub const fn from_be_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4101 Self::from_be(Self::from_ne_bytes(bytes))
4102 }
4103
4104 /// Creates a native endian integer value from its representation
4105 /// as a byte array in little endian.
4106 ///
4107 #[doc = $from_xe_bytes_doc]
4108 ///
4109 /// # Examples
4110 ///
4111 /// ```
4112 #[doc = concat!("let value = ", stringify!($SelfT), "::from_le_bytes(", $le_bytes, ");")]
4113 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4114 /// ```
4115 ///
4116 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4117 ///
4118 /// ```
4119 #[doc = concat!("fn read_le_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4120 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4121 /// *input = rest;
4122 #[doc = concat!(" ", stringify!($SelfT), "::from_le_bytes(int_bytes.try_into().unwrap())")]
4123 /// }
4124 /// ```
4125 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4126 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4127 #[must_use]
4128 #[inline]
4129 pub const fn from_le_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4130 Self::from_le(Self::from_ne_bytes(bytes))
4131 }
4132
4133 /// Creates a native endian integer value from its memory representation
4134 /// as a byte array in native endianness.
4135 ///
4136 /// As the target platform's native endianness is used, portable code
4137 /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
4138 /// appropriate instead.
4139 ///
4140 /// [`from_be_bytes`]: Self::from_be_bytes
4141 /// [`from_le_bytes`]: Self::from_le_bytes
4142 ///
4143 #[doc = $from_xe_bytes_doc]
4144 ///
4145 /// # Examples
4146 ///
4147 /// ```
4148 #[doc = concat!("let value = ", stringify!($SelfT), "::from_ne_bytes(if cfg!(target_endian = \"big\") {")]
4149 #[doc = concat!(" ", $be_bytes, "")]
4150 /// } else {
4151 #[doc = concat!(" ", $le_bytes, "")]
4152 /// });
4153 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4154 /// ```
4155 ///
4156 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4157 ///
4158 /// ```
4159 #[doc = concat!("fn read_ne_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4160 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4161 /// *input = rest;
4162 #[doc = concat!(" ", stringify!($SelfT), "::from_ne_bytes(int_bytes.try_into().unwrap())")]
4163 /// }
4164 /// ```
4165 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4166 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4167 #[allow(unnecessary_transmutes)]
4168 #[must_use]
4169 // SAFETY: const sound because integers are plain old datatypes so we can always
4170 // transmute to them
4171 #[inline]
4172 pub const fn from_ne_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4173 // SAFETY: integers are plain old datatypes so we can always transmute to them
4174 unsafe { mem::transmute(bytes) }
4175 }
4176
4177 /// New code should prefer to use
4178 #[doc = concat!("[`", stringify!($SelfT), "::MIN", "`] instead.")]
4179 ///
4180 /// Returns the smallest value that can be represented by this integer type.
4181 #[stable(feature = "rust1", since = "1.0.0")]
4182 #[rustc_promotable]
4183 #[inline(always)]
4184 #[rustc_const_stable(feature = "const_max_value", since = "1.32.0")]
4185 #[deprecated(since = "TBD", note = "replaced by the `MIN` associated constant on this type")]
4186 #[rustc_diagnostic_item = concat!(stringify!($SelfT), "_legacy_fn_min_value")]
4187 pub const fn min_value() -> Self { Self::MIN }
4188
4189 /// New code should prefer to use
4190 #[doc = concat!("[`", stringify!($SelfT), "::MAX", "`] instead.")]
4191 ///
4192 /// Returns the largest value that can be represented by this integer type.
4193 #[stable(feature = "rust1", since = "1.0.0")]
4194 #[rustc_promotable]
4195 #[inline(always)]
4196 #[rustc_const_stable(feature = "const_max_value", since = "1.32.0")]
4197 #[deprecated(since = "TBD", note = "replaced by the `MAX` associated constant on this type")]
4198 #[rustc_diagnostic_item = concat!(stringify!($SelfT), "_legacy_fn_max_value")]
4199 pub const fn max_value() -> Self { Self::MAX }
4200
4201 /// Truncate an integer to an integer of the same size or smaller, preserving the least
4202 /// significant bits.
4203 ///
4204 /// # Examples
4205 ///
4206 /// ```
4207 /// #![feature(integer_widen_truncate)]
4208 #[doc = concat!("assert_eq!(120u8, 120", stringify!($SelfT), ".truncate());")]
4209 /// assert_eq!(120u8, 376u32.truncate());
4210 /// ```
4211 #[must_use = "this returns the truncated value and does not modify the original"]
4212 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4213 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4214 #[inline]
4215 pub const fn truncate<Target>(self) -> Target
4216 where Self: [const] traits::TruncateTarget<Target>
4217 {
4218 traits::TruncateTarget::internal_truncate(self)
4219 }
4220
4221 /// Truncate an integer to an integer of the same size or smaller, saturating at numeric bounds
4222 /// instead of truncating.
4223 ///
4224 /// # Examples
4225 ///
4226 /// ```
4227 /// #![feature(integer_widen_truncate)]
4228 #[doc = concat!("assert_eq!(120u8, 120", stringify!($SelfT), ".saturating_truncate());")]
4229 /// assert_eq!(255u8, 376u32.saturating_truncate());
4230 /// ```
4231 #[must_use = "this returns the truncated value and does not modify the original"]
4232 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4233 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4234 #[inline]
4235 pub const fn saturating_truncate<Target>(self) -> Target
4236 where Self: [const] traits::TruncateTarget<Target>
4237 {
4238 traits::TruncateTarget::internal_saturating_truncate(self)
4239 }
4240
4241 /// Truncate an integer to an integer of the same size or smaller, returning `None` if the value
4242 /// is outside the bounds of the smaller type.
4243 ///
4244 /// # Examples
4245 ///
4246 /// ```
4247 /// #![feature(integer_widen_truncate)]
4248 #[doc = concat!("assert_eq!(Some(120u8), 120", stringify!($SelfT), ".checked_truncate());")]
4249 /// assert_eq!(None, 376u32.checked_truncate::<u8>());
4250 /// ```
4251 #[must_use = "this returns the truncated value and does not modify the original"]
4252 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4253 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4254 #[inline]
4255 pub const fn checked_truncate<Target>(self) -> Option<Target>
4256 where Self: [const] traits::TruncateTarget<Target>
4257 {
4258 traits::TruncateTarget::internal_checked_truncate(self)
4259 }
4260
4261 /// Widen to an integer of the same size or larger, preserving its value.
4262 ///
4263 /// # Examples
4264 ///
4265 /// ```
4266 /// #![feature(integer_widen_truncate)]
4267 #[doc = concat!("assert_eq!(120u128, 120u8.widen());")]
4268 /// ```
4269 #[must_use = "this returns the widened value and does not modify the original"]
4270 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4271 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4272 #[inline]
4273 pub const fn widen<Target>(self) -> Target
4274 where Self: [const] traits::WidenTarget<Target>
4275 {
4276 traits::WidenTarget::internal_widen(self)
4277 }
4278 }
4279}