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!($BITS), ");")]
218 /// ```
219 #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
220 #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
221 #[must_use = "this returns the result of the operation, \
222 without modifying the original"]
223 #[inline(always)]
224 pub const fn trailing_ones(self) -> u32 {
225 (!self).trailing_zeros()
226 }
227
228 /// Returns the minimum number of bits required to represent `self`.
229 ///
230 /// This method returns zero if `self` is zero.
231 ///
232 /// # Examples
233 ///
234 /// ```
235 /// #![feature(uint_bit_width)]
236 ///
237 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".bit_width(), 0);")]
238 #[doc = concat!("assert_eq!(0b111_", stringify!($SelfT), ".bit_width(), 3);")]
239 #[doc = concat!("assert_eq!(0b1110_", stringify!($SelfT), ".bit_width(), 4);")]
240 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.bit_width(), ", stringify!($BITS), ");")]
241 /// ```
242 #[unstable(feature = "uint_bit_width", issue = "142326")]
243 #[must_use = "this returns the result of the operation, \
244 without modifying the original"]
245 #[inline(always)]
246 pub const fn bit_width(self) -> u32 {
247 Self::BITS - self.leading_zeros()
248 }
249
250 /// Returns `self` with only the most significant bit set, or `0` if
251 /// the input is `0`.
252 ///
253 /// # Examples
254 ///
255 /// ```
256 /// #![feature(isolate_most_least_significant_one)]
257 ///
258 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b_01100100;")]
259 ///
260 /// assert_eq!(n.isolate_highest_one(), 0b_01000000);
261 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".isolate_highest_one(), 0);")]
262 /// ```
263 #[unstable(feature = "isolate_most_least_significant_one", issue = "136909")]
264 #[must_use = "this returns the result of the operation, \
265 without modifying the original"]
266 #[inline(always)]
267 pub const fn isolate_highest_one(self) -> Self {
268 self & (((1 as $SelfT) << (<$SelfT>::BITS - 1)).wrapping_shr(self.leading_zeros()))
269 }
270
271 /// Returns `self` with only the least significant bit set, or `0` if
272 /// the input is `0`.
273 ///
274 /// # Examples
275 ///
276 /// ```
277 /// #![feature(isolate_most_least_significant_one)]
278 ///
279 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b_01100100;")]
280 ///
281 /// assert_eq!(n.isolate_lowest_one(), 0b_00000100);
282 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".isolate_lowest_one(), 0);")]
283 /// ```
284 #[unstable(feature = "isolate_most_least_significant_one", issue = "136909")]
285 #[must_use = "this returns the result of the operation, \
286 without modifying the original"]
287 #[inline(always)]
288 pub const fn isolate_lowest_one(self) -> Self {
289 self & self.wrapping_neg()
290 }
291
292 /// Returns the index of the highest bit set to one in `self`, or `None`
293 /// if `self` is `0`.
294 ///
295 /// # Examples
296 ///
297 /// ```
298 /// #![feature(int_lowest_highest_one)]
299 ///
300 #[doc = concat!("assert_eq!(0b0_", stringify!($SelfT), ".highest_one(), None);")]
301 #[doc = concat!("assert_eq!(0b1_", stringify!($SelfT), ".highest_one(), Some(0));")]
302 #[doc = concat!("assert_eq!(0b1_0000_", stringify!($SelfT), ".highest_one(), Some(4));")]
303 #[doc = concat!("assert_eq!(0b1_1111_", stringify!($SelfT), ".highest_one(), Some(4));")]
304 /// ```
305 #[unstable(feature = "int_lowest_highest_one", issue = "145203")]
306 #[must_use = "this returns the result of the operation, \
307 without modifying the original"]
308 #[inline(always)]
309 pub const fn highest_one(self) -> Option<u32> {
310 match NonZero::new(self) {
311 Some(v) => Some(v.highest_one()),
312 None => None,
313 }
314 }
315
316 /// Returns the index of the lowest bit set to one in `self`, or `None`
317 /// if `self` is `0`.
318 ///
319 /// # Examples
320 ///
321 /// ```
322 /// #![feature(int_lowest_highest_one)]
323 ///
324 #[doc = concat!("assert_eq!(0b0_", stringify!($SelfT), ".lowest_one(), None);")]
325 #[doc = concat!("assert_eq!(0b1_", stringify!($SelfT), ".lowest_one(), Some(0));")]
326 #[doc = concat!("assert_eq!(0b1_0000_", stringify!($SelfT), ".lowest_one(), Some(4));")]
327 #[doc = concat!("assert_eq!(0b1_1111_", stringify!($SelfT), ".lowest_one(), Some(0));")]
328 /// ```
329 #[unstable(feature = "int_lowest_highest_one", issue = "145203")]
330 #[must_use = "this returns the result of the operation, \
331 without modifying the original"]
332 #[inline(always)]
333 pub const fn lowest_one(self) -> Option<u32> {
334 match NonZero::new(self) {
335 Some(v) => Some(v.lowest_one()),
336 None => None,
337 }
338 }
339
340 /// Returns the bit pattern of `self` reinterpreted as a signed integer of the same size.
341 ///
342 /// This produces the same result as an `as` cast, but ensures that the bit-width remains
343 /// the same.
344 ///
345 /// # Examples
346 ///
347 /// ```
348 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
349 ///
350 #[doc = concat!("assert_eq!(n.cast_signed(), -1", stringify!($SignedT), ");")]
351 /// ```
352 #[stable(feature = "integer_sign_cast", since = "1.87.0")]
353 #[rustc_const_stable(feature = "integer_sign_cast", since = "1.87.0")]
354 #[must_use = "this returns the result of the operation, \
355 without modifying the original"]
356 #[inline(always)]
357 pub const fn cast_signed(self) -> $SignedT {
358 self as $SignedT
359 }
360
361 /// Shifts the bits to the left by a specified amount, `n`,
362 /// wrapping the truncated bits to the end of the resulting integer.
363 ///
364 /// `rotate_left(n)` is equivalent to applying `rotate_left(1)` a total of `n` times. In
365 /// particular, a rotation by the number of bits in `self` returns the input value
366 /// unchanged.
367 ///
368 /// Please note this isn't the same operation as the `<<` shifting operator!
369 ///
370 /// # Examples
371 ///
372 /// ```
373 #[doc = concat!("let n = ", $rot_op, stringify!($SelfT), ";")]
374 #[doc = concat!("let m = ", $rot_result, ";")]
375 ///
376 #[doc = concat!("assert_eq!(n.rotate_left(", $rot, "), m);")]
377 #[doc = concat!("assert_eq!(n.rotate_left(1024), n);")]
378 /// ```
379 #[stable(feature = "rust1", since = "1.0.0")]
380 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
381 #[must_use = "this returns the result of the operation, \
382 without modifying the original"]
383 #[inline(always)]
384 #[rustc_allow_const_fn_unstable(const_trait_impl)] // for the intrinsic fallback
385 pub const fn rotate_left(self, n: u32) -> Self {
386 return intrinsics::rotate_left(self, n);
387 }
388
389 /// Shifts the bits to the right by a specified amount, `n`,
390 /// wrapping the truncated bits to the beginning of the resulting
391 /// integer.
392 ///
393 /// `rotate_right(n)` is equivalent to applying `rotate_right(1)` a total of `n` times. In
394 /// particular, a rotation by the number of bits in `self` returns the input value
395 /// unchanged.
396 ///
397 /// Please note this isn't the same operation as the `>>` shifting operator!
398 ///
399 /// # Examples
400 ///
401 /// ```
402 #[doc = concat!("let n = ", $rot_result, stringify!($SelfT), ";")]
403 #[doc = concat!("let m = ", $rot_op, ";")]
404 ///
405 #[doc = concat!("assert_eq!(n.rotate_right(", $rot, "), m);")]
406 #[doc = concat!("assert_eq!(n.rotate_right(1024), n);")]
407 /// ```
408 #[stable(feature = "rust1", since = "1.0.0")]
409 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
410 #[must_use = "this returns the result of the operation, \
411 without modifying the original"]
412 #[inline(always)]
413 #[rustc_allow_const_fn_unstable(const_trait_impl)] // for the intrinsic fallback
414 pub const fn rotate_right(self, n: u32) -> Self {
415 return intrinsics::rotate_right(self, n);
416 }
417
418 /// Performs a left funnel shift (concatenates `self` with `rhs`, with `self`
419 /// making up the most significant half, then shifts the combined value left
420 /// by `n`, and most significant half is extracted to produce the result).
421 ///
422 /// Please note this isn't the same operation as the `<<` shifting operator or
423 /// [`rotate_left`](Self::rotate_left), although `a.funnel_shl(a, n)` is *equivalent*
424 /// to `a.rotate_left(n)`.
425 ///
426 /// # Panics
427 ///
428 /// If `n` is greater than or equal to the number of bits in `self`
429 ///
430 /// # Examples
431 ///
432 /// Basic usage:
433 ///
434 /// ```
435 /// #![feature(funnel_shifts)]
436 #[doc = concat!("let a = ", $rot_op, stringify!($SelfT), ";")]
437 #[doc = concat!("let b = ", $fsh_op, stringify!($SelfT), ";")]
438 #[doc = concat!("let m = ", $fshl_result, ";")]
439 ///
440 #[doc = concat!("assert_eq!(a.funnel_shl(b, ", $rot, "), m);")]
441 /// ```
442 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
443 #[unstable(feature = "funnel_shifts", issue = "145686")]
444 #[must_use = "this returns the result of the operation, \
445 without modifying the original"]
446 #[inline(always)]
447 pub const fn funnel_shl(self, rhs: Self, n: u32) -> Self {
448 assert!(n < Self::BITS, "attempt to funnel shift left with overflow");
449 // SAFETY: just checked that `shift` is in-range
450 unsafe { self.unchecked_funnel_shl(rhs, n) }
451 }
452
453 /// Performs a right funnel shift (concatenates `self` and `rhs`, with `self`
454 /// making up the most significant half, then shifts the combined value right
455 /// by `n`, and least significant half is extracted to produce the result).
456 ///
457 /// Please note this isn't the same operation as the `>>` shifting operator or
458 /// [`rotate_right`](Self::rotate_right), although `a.funnel_shr(a, n)` is *equivalent*
459 /// to `a.rotate_right(n)`.
460 ///
461 /// # Panics
462 ///
463 /// If `n` is greater than or equal to the number of bits in `self`
464 ///
465 /// # Examples
466 ///
467 /// Basic usage:
468 ///
469 /// ```
470 /// #![feature(funnel_shifts)]
471 #[doc = concat!("let a = ", $rot_op, stringify!($SelfT), ";")]
472 #[doc = concat!("let b = ", $fsh_op, stringify!($SelfT), ";")]
473 #[doc = concat!("let m = ", $fshr_result, ";")]
474 ///
475 #[doc = concat!("assert_eq!(a.funnel_shr(b, ", $rot, "), m);")]
476 /// ```
477 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
478 #[unstable(feature = "funnel_shifts", issue = "145686")]
479 #[must_use = "this returns the result of the operation, \
480 without modifying the original"]
481 #[inline(always)]
482 pub const fn funnel_shr(self, rhs: Self, n: u32) -> Self {
483 assert!(n < Self::BITS, "attempt to funnel shift right with overflow");
484 // SAFETY: just checked that `shift` is in-range
485 unsafe { self.unchecked_funnel_shr(rhs, n) }
486 }
487
488 /// Unchecked funnel shift left.
489 ///
490 /// # Safety
491 ///
492 /// This results in undefined behavior if `n` is greater than or equal to
493 #[doc = concat!("`", stringify!($SelfT) , "::BITS`,")]
494 /// i.e. when [`funnel_shl`](Self::funnel_shl) would panic.
495 ///
496 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
497 #[unstable(feature = "funnel_shifts", issue = "145686")]
498 #[must_use = "this returns the result of the operation, \
499 without modifying the original"]
500 #[inline(always)]
501 #[track_caller]
502 pub const unsafe fn unchecked_funnel_shl(self, low: Self, n: u32) -> Self {
503 assert_unsafe_precondition!(
504 check_language_ub,
505 concat!(stringify!($SelfT), "::unchecked_funnel_shl cannot overflow"),
506 (n: u32 = n) => n < <$ActualT>::BITS,
507 );
508
509 // SAFETY: this is guaranteed to be safe by the caller.
510 unsafe {
511 intrinsics::unchecked_funnel_shl(self, low, n)
512 }
513 }
514
515 /// Unchecked funnel shift right.
516 ///
517 /// # Safety
518 ///
519 /// This results in undefined behavior if `n` is greater than or equal to
520 #[doc = concat!("`", stringify!($SelfT) , "::BITS`,")]
521 /// i.e. when [`funnel_shr`](Self::funnel_shr) would panic.
522 ///
523 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
524 #[unstable(feature = "funnel_shifts", issue = "145686")]
525 #[must_use = "this returns the result of the operation, \
526 without modifying the original"]
527 #[inline(always)]
528 #[track_caller]
529 pub const unsafe fn unchecked_funnel_shr(self, low: Self, n: u32) -> Self {
530 assert_unsafe_precondition!(
531 check_language_ub,
532 concat!(stringify!($SelfT), "::unchecked_funnel_shr cannot overflow"),
533 (n: u32 = n) => n < <$ActualT>::BITS,
534 );
535
536 // SAFETY: this is guaranteed to be safe by the caller.
537 unsafe {
538 intrinsics::unchecked_funnel_shr(self, low, n)
539 }
540 }
541
542 /// Performs a carry-less multiplication, returning the lower bits.
543 ///
544 /// This operation is similar to long multiplication in base 2, except that exclusive or is
545 /// used instead of addition. The implementation is equivalent to:
546 ///
547 /// ```no_run
548 #[doc = concat!("pub fn carryless_mul(lhs: ", stringify!($SelfT), ", rhs: ", stringify!($SelfT), ") -> ", stringify!($SelfT), "{")]
549 /// let mut retval = 0;
550 #[doc = concat!(" for i in 0..", stringify!($SelfT), "::BITS {")]
551 /// if (rhs >> i) & 1 != 0 {
552 /// // long multiplication would use +=
553 /// retval ^= lhs << i;
554 /// }
555 /// }
556 /// retval
557 /// }
558 /// ```
559 ///
560 /// The actual implementation is more efficient, and on some platforms lowers directly to a
561 /// dedicated instruction.
562 ///
563 /// # Uses
564 ///
565 /// Carryless multiplication can be used to turn a bitmask of quote characters into a
566 /// bit mask of characters surrounded by quotes:
567 ///
568 /// ```no_run
569 /// r#"abc xxx "foobar" zzz "a"!"#; // input string
570 /// 0b0000000010000001000001010; // quote_mask
571 /// 0b0000000001111110000000100; // quote_mask.carryless_mul(!0) & !quote_mask
572 /// ```
573 ///
574 /// Another use is in cryptography, where carryless multiplication allows for efficient
575 /// implementations of polynomial multiplication in `GF(2)[X]`, the polynomial ring
576 /// over `GF(2)`.
577 ///
578 /// # Examples
579 ///
580 /// ```
581 /// #![feature(uint_carryless_mul)]
582 ///
583 #[doc = concat!("let a = ", $clmul_lhs, stringify!($SelfT), ";")]
584 #[doc = concat!("let b = ", $clmul_rhs, stringify!($SelfT), ";")]
585 ///
586 #[doc = concat!("assert_eq!(a.carryless_mul(b), ", $clmul_result, ");")]
587 /// ```
588 #[rustc_const_unstable(feature = "uint_carryless_mul", issue = "152080")]
589 #[doc(alias = "clmul")]
590 #[unstable(feature = "uint_carryless_mul", issue = "152080")]
591 #[must_use = "this returns the result of the operation, \
592 without modifying the original"]
593 #[inline(always)]
594 pub const fn carryless_mul(self, rhs: Self) -> Self {
595 intrinsics::carryless_mul(self, rhs)
596 }
597
598 /// Reverses the byte order of the integer.
599 ///
600 /// # Examples
601 ///
602 /// ```
603 #[doc = concat!("let n = ", $swap_op, stringify!($SelfT), ";")]
604 /// let m = n.swap_bytes();
605 ///
606 #[doc = concat!("assert_eq!(m, ", $swapped, ");")]
607 /// ```
608 #[stable(feature = "rust1", since = "1.0.0")]
609 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
610 #[must_use = "this returns the result of the operation, \
611 without modifying the original"]
612 #[inline(always)]
613 pub const fn swap_bytes(self) -> Self {
614 intrinsics::bswap(self as $ActualT) as Self
615 }
616
617 /// Returns an integer with the bit locations specified by `mask` packed
618 /// contiguously into the least significant bits of the result.
619 /// ```
620 /// #![feature(uint_gather_scatter_bits)]
621 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b1011_1100;")]
622 ///
623 /// assert_eq!(n.extract_bits(0b0010_0100), 0b0000_0011);
624 /// assert_eq!(n.extract_bits(0xF0), 0b0000_1011);
625 /// ```
626 #[unstable(feature = "uint_gather_scatter_bits", issue = "149069")]
627 #[must_use = "this returns the result of the operation, \
628 without modifying the original"]
629 #[inline]
630 pub const fn extract_bits(self, mask: Self) -> Self {
631 imp::int_bits::$ActualT::extract_impl(self as $ActualT, mask as $ActualT) as $SelfT
632 }
633
634 /// Returns an integer with the least significant bits of `self`
635 /// distributed to the bit locations specified by `mask`.
636 /// ```
637 /// #![feature(uint_gather_scatter_bits)]
638 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b1010_1101;")]
639 ///
640 /// assert_eq!(n.deposit_bits(0b0101_0101), 0b0101_0001);
641 /// assert_eq!(n.deposit_bits(0xF0), 0b1101_0000);
642 /// ```
643 #[unstable(feature = "uint_gather_scatter_bits", issue = "149069")]
644 #[must_use = "this returns the result of the operation, \
645 without modifying the original"]
646 #[inline]
647 pub const fn deposit_bits(self, mask: Self) -> Self {
648 imp::int_bits::$ActualT::deposit_impl(self as $ActualT, mask as $ActualT) as $SelfT
649 }
650
651 /// Reverses the order of bits in the integer. The least significant bit becomes the most significant bit,
652 /// second least-significant bit becomes second most-significant bit, etc.
653 ///
654 /// # Examples
655 ///
656 /// ```
657 #[doc = concat!("let n = ", $swap_op, stringify!($SelfT), ";")]
658 /// let m = n.reverse_bits();
659 ///
660 #[doc = concat!("assert_eq!(m, ", $reversed, ");")]
661 #[doc = concat!("assert_eq!(0, 0", stringify!($SelfT), ".reverse_bits());")]
662 /// ```
663 #[stable(feature = "reverse_bits", since = "1.37.0")]
664 #[rustc_const_stable(feature = "reverse_bits", since = "1.37.0")]
665 #[must_use = "this returns the result of the operation, \
666 without modifying the original"]
667 #[inline(always)]
668 pub const fn reverse_bits(self) -> Self {
669 intrinsics::bitreverse(self as $ActualT) as Self
670 }
671
672 /// Converts an integer from big endian to the target's endianness.
673 ///
674 /// On big endian this is a no-op. On little endian the bytes are
675 /// swapped.
676 ///
677 /// # Examples
678 ///
679 /// ```
680 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
681 ///
682 /// if cfg!(target_endian = "big") {
683 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_be(n), n)")]
684 /// } else {
685 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_be(n), n.swap_bytes())")]
686 /// }
687 /// ```
688 #[stable(feature = "rust1", since = "1.0.0")]
689 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
690 #[must_use]
691 #[inline(always)]
692 pub const fn from_be(x: Self) -> Self {
693 #[cfg(target_endian = "big")]
694 {
695 x
696 }
697 #[cfg(not(target_endian = "big"))]
698 {
699 x.swap_bytes()
700 }
701 }
702
703 /// Converts an integer from little endian to the target's endianness.
704 ///
705 /// On little endian this is a no-op. On big endian the bytes are
706 /// swapped.
707 ///
708 /// # Examples
709 ///
710 /// ```
711 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
712 ///
713 /// if cfg!(target_endian = "little") {
714 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_le(n), n)")]
715 /// } else {
716 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_le(n), n.swap_bytes())")]
717 /// }
718 /// ```
719 #[stable(feature = "rust1", since = "1.0.0")]
720 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
721 #[must_use]
722 #[inline(always)]
723 pub const fn from_le(x: Self) -> Self {
724 #[cfg(target_endian = "little")]
725 {
726 x
727 }
728 #[cfg(not(target_endian = "little"))]
729 {
730 x.swap_bytes()
731 }
732 }
733
734 /// Converts `self` to big endian from the target's endianness.
735 ///
736 /// On big endian this is a no-op. On little endian the bytes are
737 /// swapped.
738 ///
739 /// # Examples
740 ///
741 /// ```
742 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
743 ///
744 /// if cfg!(target_endian = "big") {
745 /// assert_eq!(n.to_be(), n)
746 /// } else {
747 /// assert_eq!(n.to_be(), n.swap_bytes())
748 /// }
749 /// ```
750 #[stable(feature = "rust1", since = "1.0.0")]
751 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
752 #[must_use = "this returns the result of the operation, \
753 without modifying the original"]
754 #[inline(always)]
755 pub const fn to_be(self) -> Self { // or not to be?
756 #[cfg(target_endian = "big")]
757 {
758 self
759 }
760 #[cfg(not(target_endian = "big"))]
761 {
762 self.swap_bytes()
763 }
764 }
765
766 /// Converts `self` to little endian from the target's endianness.
767 ///
768 /// On little endian this is a no-op. On big endian the bytes are
769 /// swapped.
770 ///
771 /// # Examples
772 ///
773 /// ```
774 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
775 ///
776 /// if cfg!(target_endian = "little") {
777 /// assert_eq!(n.to_le(), n)
778 /// } else {
779 /// assert_eq!(n.to_le(), n.swap_bytes())
780 /// }
781 /// ```
782 #[stable(feature = "rust1", since = "1.0.0")]
783 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
784 #[must_use = "this returns the result of the operation, \
785 without modifying the original"]
786 #[inline(always)]
787 pub const fn to_le(self) -> Self {
788 #[cfg(target_endian = "little")]
789 {
790 self
791 }
792 #[cfg(not(target_endian = "little"))]
793 {
794 self.swap_bytes()
795 }
796 }
797
798 /// Checked integer addition. Computes `self + rhs`, returning `None`
799 /// if overflow occurred.
800 ///
801 /// # Examples
802 ///
803 /// ```
804 #[doc = concat!(
805 "assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add(1), ",
806 "Some(", stringify!($SelfT), "::MAX - 1));"
807 )]
808 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add(3), None);")]
809 /// ```
810 #[stable(feature = "rust1", since = "1.0.0")]
811 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
812 #[must_use = "this returns the result of the operation, \
813 without modifying the original"]
814 #[inline]
815 pub const fn checked_add(self, rhs: Self) -> Option<Self> {
816 // This used to use `overflowing_add`, but that means it ends up being
817 // a `wrapping_add`, losing some optimization opportunities. Notably,
818 // phrasing it this way helps `.checked_add(1)` optimize to a check
819 // against `MAX` and a `add nuw`.
820 // Per <https://github.com/rust-lang/rust/pull/124114#issuecomment-2066173305>,
821 // LLVM is happy to re-form the intrinsic later if useful.
822
823 if intrinsics::unlikely(intrinsics::add_with_overflow(self, rhs).1) {
824 None
825 } else {
826 // SAFETY: Just checked it doesn't overflow
827 Some(unsafe { intrinsics::unchecked_add(self, rhs) })
828 }
829 }
830
831 /// Strict integer addition. Computes `self + rhs`, panicking
832 /// if overflow occurred.
833 ///
834 /// # Panics
835 ///
836 /// ## Overflow behavior
837 ///
838 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
839 ///
840 /// # Examples
841 ///
842 /// ```
843 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).strict_add(1), ", stringify!($SelfT), "::MAX - 1);")]
844 /// ```
845 ///
846 /// The following panics because of overflow:
847 ///
848 /// ```should_panic
849 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX - 2).strict_add(3);")]
850 /// ```
851 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
852 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
853 #[must_use = "this returns the result of the operation, \
854 without modifying the original"]
855 #[inline]
856 #[track_caller]
857 pub const fn strict_add(self, rhs: Self) -> Self {
858 let (a, b) = self.overflowing_add(rhs);
859 if b { imp::overflow_panic::add() } else { a }
860 }
861
862 /// Unchecked integer addition. Computes `self + rhs`, assuming overflow
863 /// cannot occur.
864 ///
865 /// Calling `x.unchecked_add(y)` is semantically equivalent to calling
866 /// `x.`[`checked_add`]`(y).`[`unwrap_unchecked`]`()`.
867 ///
868 /// If you're just trying to avoid the panic in debug mode, then **do not**
869 /// use this. Instead, you're looking for [`wrapping_add`].
870 ///
871 /// # Safety
872 ///
873 /// This results in undefined behavior when
874 #[doc = concat!("`self + rhs > ", stringify!($SelfT), "::MAX` or `self + rhs < ", stringify!($SelfT), "::MIN`,")]
875 /// i.e. when [`checked_add`] would return `None`.
876 ///
877 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
878 #[doc = concat!("[`checked_add`]: ", stringify!($SelfT), "::checked_add")]
879 #[doc = concat!("[`wrapping_add`]: ", stringify!($SelfT), "::wrapping_add")]
880 #[stable(feature = "unchecked_math", since = "1.79.0")]
881 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
882 #[must_use = "this returns the result of the operation, \
883 without modifying the original"]
884 #[inline(always)]
885 #[track_caller]
886 pub const unsafe fn unchecked_add(self, rhs: Self) -> Self {
887 assert_unsafe_precondition!(
888 check_language_ub,
889 concat!(stringify!($SelfT), "::unchecked_add cannot overflow"),
890 (
891 lhs: $SelfT = self,
892 rhs: $SelfT = rhs,
893 ) => !lhs.overflowing_add(rhs).1,
894 );
895
896 // SAFETY: this is guaranteed to be safe by the caller.
897 unsafe {
898 intrinsics::unchecked_add(self, rhs)
899 }
900 }
901
902 /// Checked addition with a signed integer. Computes `self + rhs`,
903 /// returning `None` if overflow occurred.
904 ///
905 /// # Examples
906 ///
907 /// ```
908 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_add_signed(2), Some(3));")]
909 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_add_signed(-2), None);")]
910 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add_signed(3), None);")]
911 /// ```
912 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
913 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
914 #[must_use = "this returns the result of the operation, \
915 without modifying the original"]
916 #[inline]
917 pub const fn checked_add_signed(self, rhs: $SignedT) -> Option<Self> {
918 let (a, b) = self.overflowing_add_signed(rhs);
919 if intrinsics::unlikely(b) { None } else { Some(a) }
920 }
921
922 /// Strict addition with a signed integer. Computes `self + rhs`,
923 /// panicking if overflow occurred.
924 ///
925 /// # Panics
926 ///
927 /// ## Overflow behavior
928 ///
929 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
930 ///
931 /// # Examples
932 ///
933 /// ```
934 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".strict_add_signed(2), 3);")]
935 /// ```
936 ///
937 /// The following panic because of overflow:
938 ///
939 /// ```should_panic
940 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_add_signed(-2);")]
941 /// ```
942 ///
943 /// ```should_panic
944 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX - 2).strict_add_signed(3);")]
945 /// ```
946 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
947 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
948 #[must_use = "this returns the result of the operation, \
949 without modifying the original"]
950 #[inline]
951 #[track_caller]
952 pub const fn strict_add_signed(self, rhs: $SignedT) -> Self {
953 let (a, b) = self.overflowing_add_signed(rhs);
954 if b { imp::overflow_panic::add() } else { a }
955 }
956
957 /// Checked integer subtraction. Computes `self - rhs`, returning
958 /// `None` if overflow occurred.
959 ///
960 /// # Examples
961 ///
962 /// ```
963 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub(1), Some(0));")]
964 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_sub(1), None);")]
965 /// ```
966 #[stable(feature = "rust1", since = "1.0.0")]
967 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
968 #[must_use = "this returns the result of the operation, \
969 without modifying the original"]
970 #[inline]
971 pub const fn checked_sub(self, rhs: Self) -> Option<Self> {
972 // Per PR#103299, there's no advantage to the `overflowing` intrinsic
973 // for *unsigned* subtraction and we just emit the manual check anyway.
974 // Thus, rather than using `overflowing_sub` that produces a wrapping
975 // subtraction, check it ourself so we can use an unchecked one.
976
977 if self < rhs {
978 None
979 } else {
980 // SAFETY: just checked this can't overflow
981 Some(unsafe { intrinsics::unchecked_sub(self, rhs) })
982 }
983 }
984
985 /// Strict integer subtraction. Computes `self - rhs`, panicking if
986 /// overflow occurred.
987 ///
988 /// # Panics
989 ///
990 /// ## Overflow behavior
991 ///
992 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
993 ///
994 /// # Examples
995 ///
996 /// ```
997 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".strict_sub(1), 0);")]
998 /// ```
999 ///
1000 /// The following panics because of overflow:
1001 ///
1002 /// ```should_panic
1003 #[doc = concat!("let _ = 0", stringify!($SelfT), ".strict_sub(1);")]
1004 /// ```
1005 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1006 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1007 #[must_use = "this returns the result of the operation, \
1008 without modifying the original"]
1009 #[inline]
1010 #[track_caller]
1011 pub const fn strict_sub(self, rhs: Self) -> Self {
1012 let (a, b) = self.overflowing_sub(rhs);
1013 if b { imp::overflow_panic::sub() } else { a }
1014 }
1015
1016 /// Unchecked integer subtraction. Computes `self - rhs`, assuming overflow
1017 /// cannot occur.
1018 ///
1019 /// Calling `x.unchecked_sub(y)` is semantically equivalent to calling
1020 /// `x.`[`checked_sub`]`(y).`[`unwrap_unchecked`]`()`.
1021 ///
1022 /// If you're just trying to avoid the panic in debug mode, then **do not**
1023 /// use this. Instead, you're looking for [`wrapping_sub`].
1024 ///
1025 /// If you find yourself writing code like this:
1026 ///
1027 /// ```
1028 /// # let foo = 30_u32;
1029 /// # let bar = 20;
1030 /// if foo >= bar {
1031 /// // SAFETY: just checked it will not overflow
1032 /// let diff = unsafe { foo.unchecked_sub(bar) };
1033 /// // ... use diff ...
1034 /// }
1035 /// ```
1036 ///
1037 /// Consider changing it to
1038 ///
1039 /// ```
1040 /// # let foo = 30_u32;
1041 /// # let bar = 20;
1042 /// if let Some(diff) = foo.checked_sub(bar) {
1043 /// // ... use diff ...
1044 /// }
1045 /// ```
1046 ///
1047 /// As that does exactly the same thing -- including telling the optimizer
1048 /// that the subtraction cannot overflow -- but avoids needing `unsafe`.
1049 ///
1050 /// # Safety
1051 ///
1052 /// This results in undefined behavior when
1053 #[doc = concat!("`self - rhs > ", stringify!($SelfT), "::MAX` or `self - rhs < ", stringify!($SelfT), "::MIN`,")]
1054 /// i.e. when [`checked_sub`] would return `None`.
1055 ///
1056 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
1057 #[doc = concat!("[`checked_sub`]: ", stringify!($SelfT), "::checked_sub")]
1058 #[doc = concat!("[`wrapping_sub`]: ", stringify!($SelfT), "::wrapping_sub")]
1059 #[stable(feature = "unchecked_math", since = "1.79.0")]
1060 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
1061 #[must_use = "this returns the result of the operation, \
1062 without modifying the original"]
1063 #[inline(always)]
1064 #[track_caller]
1065 pub const unsafe fn unchecked_sub(self, rhs: Self) -> Self {
1066 assert_unsafe_precondition!(
1067 check_language_ub,
1068 concat!(stringify!($SelfT), "::unchecked_sub cannot overflow"),
1069 (
1070 lhs: $SelfT = self,
1071 rhs: $SelfT = rhs,
1072 ) => !lhs.overflowing_sub(rhs).1,
1073 );
1074
1075 // SAFETY: this is guaranteed to be safe by the caller.
1076 unsafe {
1077 intrinsics::unchecked_sub(self, rhs)
1078 }
1079 }
1080
1081 /// Checked subtraction with a signed integer. Computes `self - rhs`,
1082 /// returning `None` if overflow occurred.
1083 ///
1084 /// # Examples
1085 ///
1086 /// ```
1087 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_signed(2), None);")]
1088 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_signed(-2), Some(3));")]
1089 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_sub_signed(-4), None);")]
1090 /// ```
1091 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
1092 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
1093 #[must_use = "this returns the result of the operation, \
1094 without modifying the original"]
1095 #[inline]
1096 pub const fn checked_sub_signed(self, rhs: $SignedT) -> Option<Self> {
1097 let (res, overflow) = self.overflowing_sub_signed(rhs);
1098
1099 if !overflow {
1100 Some(res)
1101 } else {
1102 None
1103 }
1104 }
1105
1106 /// Strict subtraction with a signed integer. Computes `self - rhs`,
1107 /// panicking if overflow occurred.
1108 ///
1109 /// # Panics
1110 ///
1111 /// ## Overflow behavior
1112 ///
1113 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1114 ///
1115 /// # Examples
1116 ///
1117 /// ```
1118 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".strict_sub_signed(2), 1);")]
1119 /// ```
1120 ///
1121 /// The following panic because of overflow:
1122 ///
1123 /// ```should_panic
1124 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_sub_signed(2);")]
1125 /// ```
1126 ///
1127 /// ```should_panic
1128 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX).strict_sub_signed(-1);")]
1129 /// ```
1130 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1131 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1132 #[must_use = "this returns the result of the operation, \
1133 without modifying the original"]
1134 #[inline]
1135 #[track_caller]
1136 pub const fn strict_sub_signed(self, rhs: $SignedT) -> Self {
1137 let (a, b) = self.overflowing_sub_signed(rhs);
1138 if b { imp::overflow_panic::sub() } else { a }
1139 }
1140
1141 #[doc = concat!(
1142 "Checked integer subtraction. Computes `self - rhs` and checks if the result fits into an [`",
1143 stringify!($SignedT), "`], returning `None` if overflow occurred."
1144 )]
1145 ///
1146 /// # Examples
1147 ///
1148 /// ```
1149 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".checked_signed_diff(2), Some(8));")]
1150 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_signed_diff(10), Some(-8));")]
1151 #[doc = concat!(
1152 "assert_eq!(",
1153 stringify!($SelfT),
1154 "::MAX.checked_signed_diff(",
1155 stringify!($SignedT),
1156 "::MAX as ",
1157 stringify!($SelfT),
1158 "), None);"
1159 )]
1160 #[doc = concat!(
1161 "assert_eq!((",
1162 stringify!($SignedT),
1163 "::MAX as ",
1164 stringify!($SelfT),
1165 ").checked_signed_diff(",
1166 stringify!($SelfT),
1167 "::MAX), Some(",
1168 stringify!($SignedT),
1169 "::MIN));"
1170 )]
1171 #[doc = concat!(
1172 "assert_eq!((",
1173 stringify!($SignedT),
1174 "::MAX as ",
1175 stringify!($SelfT),
1176 " + 1).checked_signed_diff(0), None);"
1177 )]
1178 #[doc = concat!(
1179 "assert_eq!(",
1180 stringify!($SelfT),
1181 "::MAX.checked_signed_diff(",
1182 stringify!($SelfT),
1183 "::MAX), Some(0));"
1184 )]
1185 /// ```
1186 #[stable(feature = "unsigned_signed_diff", since = "1.91.0")]
1187 #[rustc_const_stable(feature = "unsigned_signed_diff", since = "1.91.0")]
1188 #[inline]
1189 pub const fn checked_signed_diff(self, rhs: Self) -> Option<$SignedT> {
1190 let res = self.wrapping_sub(rhs) as $SignedT;
1191 let overflow = (self >= rhs) == (res < 0);
1192
1193 if !overflow {
1194 Some(res)
1195 } else {
1196 None
1197 }
1198 }
1199
1200 /// Checked integer multiplication. Computes `self * rhs`, returning
1201 /// `None` if overflow occurred.
1202 ///
1203 /// # Examples
1204 ///
1205 /// ```
1206 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_mul(1), Some(5));")]
1207 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_mul(2), None);")]
1208 /// ```
1209 #[stable(feature = "rust1", since = "1.0.0")]
1210 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1211 #[must_use = "this returns the result of the operation, \
1212 without modifying the original"]
1213 #[inline]
1214 pub const fn checked_mul(self, rhs: Self) -> Option<Self> {
1215 let (a, b) = self.overflowing_mul(rhs);
1216 if intrinsics::unlikely(b) { None } else { Some(a) }
1217 }
1218
1219 /// Strict integer multiplication. Computes `self * rhs`, panicking if
1220 /// overflow occurred.
1221 ///
1222 /// # Panics
1223 ///
1224 /// ## Overflow behavior
1225 ///
1226 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1227 ///
1228 /// # Examples
1229 ///
1230 /// ```
1231 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".strict_mul(1), 5);")]
1232 /// ```
1233 ///
1234 /// The following panics because of overflow:
1235 ///
1236 /// ``` should_panic
1237 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_mul(2);")]
1238 /// ```
1239 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1240 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1241 #[must_use = "this returns the result of the operation, \
1242 without modifying the original"]
1243 #[inline]
1244 #[track_caller]
1245 pub const fn strict_mul(self, rhs: Self) -> Self {
1246 let (a, b) = self.overflowing_mul(rhs);
1247 if b { imp::overflow_panic::mul() } else { a }
1248 }
1249
1250 /// Unchecked integer multiplication. Computes `self * rhs`, assuming overflow
1251 /// cannot occur.
1252 ///
1253 /// Calling `x.unchecked_mul(y)` is semantically equivalent to calling
1254 /// `x.`[`checked_mul`]`(y).`[`unwrap_unchecked`]`()`.
1255 ///
1256 /// If you're just trying to avoid the panic in debug mode, then **do not**
1257 /// use this. Instead, you're looking for [`wrapping_mul`].
1258 ///
1259 /// # Safety
1260 ///
1261 /// This results in undefined behavior when
1262 #[doc = concat!("`self * rhs > ", stringify!($SelfT), "::MAX` or `self * rhs < ", stringify!($SelfT), "::MIN`,")]
1263 /// i.e. when [`checked_mul`] would return `None`.
1264 ///
1265 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
1266 #[doc = concat!("[`checked_mul`]: ", stringify!($SelfT), "::checked_mul")]
1267 #[doc = concat!("[`wrapping_mul`]: ", stringify!($SelfT), "::wrapping_mul")]
1268 #[stable(feature = "unchecked_math", since = "1.79.0")]
1269 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
1270 #[must_use = "this returns the result of the operation, \
1271 without modifying the original"]
1272 #[inline(always)]
1273 #[track_caller]
1274 pub const unsafe fn unchecked_mul(self, rhs: Self) -> Self {
1275 assert_unsafe_precondition!(
1276 check_language_ub,
1277 concat!(stringify!($SelfT), "::unchecked_mul cannot overflow"),
1278 (
1279 lhs: $SelfT = self,
1280 rhs: $SelfT = rhs,
1281 ) => !lhs.overflowing_mul(rhs).1,
1282 );
1283
1284 // SAFETY: this is guaranteed to be safe by the caller.
1285 unsafe {
1286 intrinsics::unchecked_mul(self, rhs)
1287 }
1288 }
1289
1290 /// Checked integer division. Computes `self / rhs`, returning `None`
1291 /// if `rhs == 0`.
1292 ///
1293 /// # Examples
1294 ///
1295 /// ```
1296 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_div(2), Some(64));")]
1297 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_div(0), None);")]
1298 /// ```
1299 #[stable(feature = "rust1", since = "1.0.0")]
1300 #[rustc_const_stable(feature = "const_checked_int_div", since = "1.52.0")]
1301 #[must_use = "this returns the result of the operation, \
1302 without modifying the original"]
1303 #[inline]
1304 pub const fn checked_div(self, rhs: Self) -> Option<Self> {
1305 if intrinsics::unlikely(rhs == 0) {
1306 None
1307 } else {
1308 // SAFETY: div by zero has been checked above and unsigned types have no other
1309 // failure modes for division
1310 Some(unsafe { intrinsics::unchecked_div(self, rhs) })
1311 }
1312 }
1313
1314 /// Strict integer division. Computes `self / rhs`.
1315 ///
1316 /// Strict division on unsigned types is just normal division. There's no
1317 /// way overflow could ever happen. This function exists so that all
1318 /// operations are accounted for in the strict operations.
1319 ///
1320 /// # Panics
1321 ///
1322 /// This function will panic if `rhs` is zero.
1323 ///
1324 /// # Examples
1325 ///
1326 /// ```
1327 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_div(10), 10);")]
1328 /// ```
1329 ///
1330 /// The following panics because of division by zero:
1331 ///
1332 /// ```should_panic
1333 #[doc = concat!("let _ = (1", stringify!($SelfT), ").strict_div(0);")]
1334 /// ```
1335 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1336 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1337 #[must_use = "this returns the result of the operation, \
1338 without modifying the original"]
1339 #[inline(always)]
1340 #[track_caller]
1341 pub const fn strict_div(self, rhs: Self) -> Self {
1342 self / rhs
1343 }
1344
1345 /// Checked Euclidean division. Computes `self.div_euclid(rhs)`, returning `None`
1346 /// if `rhs == 0`.
1347 ///
1348 /// # Examples
1349 ///
1350 /// ```
1351 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_div_euclid(2), Some(64));")]
1352 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_div_euclid(0), None);")]
1353 /// ```
1354 #[stable(feature = "euclidean_division", since = "1.38.0")]
1355 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
1356 #[must_use = "this returns the result of the operation, \
1357 without modifying the original"]
1358 #[inline]
1359 pub const fn checked_div_euclid(self, rhs: Self) -> Option<Self> {
1360 if intrinsics::unlikely(rhs == 0) {
1361 None
1362 } else {
1363 Some(self.div_euclid(rhs))
1364 }
1365 }
1366
1367 /// Strict Euclidean division. Computes `self.div_euclid(rhs)`.
1368 ///
1369 /// Strict division on unsigned types is just normal division. There's no
1370 /// way overflow could ever happen. This function exists so that all
1371 /// operations are accounted for in the strict operations. Since, for the
1372 /// positive integers, all common definitions of division are equal, this
1373 /// is exactly equal to `self.strict_div(rhs)`.
1374 ///
1375 /// # Panics
1376 ///
1377 /// This function will panic if `rhs` is zero.
1378 ///
1379 /// # Examples
1380 ///
1381 /// ```
1382 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_div_euclid(10), 10);")]
1383 /// ```
1384 /// The following panics because of division by zero:
1385 ///
1386 /// ```should_panic
1387 #[doc = concat!("let _ = (1", stringify!($SelfT), ").strict_div_euclid(0);")]
1388 /// ```
1389 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1390 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1391 #[must_use = "this returns the result of the operation, \
1392 without modifying the original"]
1393 #[inline(always)]
1394 #[track_caller]
1395 pub const fn strict_div_euclid(self, rhs: Self) -> Self {
1396 self / rhs
1397 }
1398
1399 /// Checked integer division without remainder. Computes `self / rhs`,
1400 /// returning `None` if `rhs == 0` or if `self % rhs != 0`.
1401 ///
1402 /// # Examples
1403 ///
1404 /// ```
1405 /// #![feature(exact_div)]
1406 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(2), Some(32));")]
1407 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(32), Some(2));")]
1408 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(0), None);")]
1409 #[doc = concat!("assert_eq!(65", stringify!($SelfT), ".checked_div_exact(2), None);")]
1410 /// ```
1411 #[unstable(
1412 feature = "exact_div",
1413 issue = "139911",
1414 )]
1415 #[must_use = "this returns the result of the operation, \
1416 without modifying the original"]
1417 #[inline]
1418 pub const fn checked_div_exact(self, rhs: Self) -> Option<Self> {
1419 if intrinsics::unlikely(rhs == 0) {
1420 None
1421 } else {
1422 // SAFETY: division by zero is checked above
1423 unsafe {
1424 if intrinsics::unlikely(intrinsics::unchecked_rem(self, rhs) != 0) {
1425 None
1426 } else {
1427 Some(intrinsics::exact_div(self, rhs))
1428 }
1429 }
1430 }
1431 }
1432
1433 /// Integer division without remainder. Computes `self / rhs`, returning `None` if `self % rhs != 0`.
1434 ///
1435 /// # Panics
1436 ///
1437 /// This function will panic if `rhs == 0`.
1438 ///
1439 /// # Examples
1440 ///
1441 /// ```
1442 /// #![feature(exact_div)]
1443 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".div_exact(2), Some(32));")]
1444 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".div_exact(32), Some(2));")]
1445 #[doc = concat!("assert_eq!(65", stringify!($SelfT), ".div_exact(2), None);")]
1446 /// ```
1447 #[unstable(
1448 feature = "exact_div",
1449 issue = "139911",
1450 )]
1451 #[must_use = "this returns the result of the operation, \
1452 without modifying the original"]
1453 #[inline]
1454 #[rustc_inherit_overflow_checks]
1455 pub const fn div_exact(self, rhs: Self) -> Option<Self> {
1456 if self % rhs != 0 {
1457 None
1458 } else {
1459 Some(self / rhs)
1460 }
1461 }
1462
1463 /// Unchecked integer division without remainder. Computes `self / rhs`.
1464 ///
1465 /// # Safety
1466 ///
1467 /// This results in undefined behavior when `rhs == 0` or `self % rhs != 0`,
1468 /// i.e. when [`checked_div_exact`](Self::checked_div_exact) would return `None`.
1469 #[unstable(
1470 feature = "exact_div",
1471 issue = "139911",
1472 )]
1473 #[must_use = "this returns the result of the operation, \
1474 without modifying the original"]
1475 #[inline]
1476 pub const unsafe fn unchecked_div_exact(self, rhs: Self) -> Self {
1477 assert_unsafe_precondition!(
1478 check_language_ub,
1479 concat!(stringify!($SelfT), "::unchecked_div_exact divide by zero or leave a remainder"),
1480 (
1481 lhs: $SelfT = self,
1482 rhs: $SelfT = rhs,
1483 ) => rhs > 0 && lhs % rhs == 0,
1484 );
1485 // SAFETY: Same precondition
1486 unsafe { intrinsics::exact_div(self, rhs) }
1487 }
1488
1489 /// Checked integer remainder. Computes `self % rhs`, returning `None`
1490 /// if `rhs == 0`.
1491 ///
1492 /// # Examples
1493 ///
1494 /// ```
1495 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem(2), Some(1));")]
1496 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem(0), None);")]
1497 /// ```
1498 #[stable(feature = "wrapping", since = "1.7.0")]
1499 #[rustc_const_stable(feature = "const_checked_int_div", since = "1.52.0")]
1500 #[must_use = "this returns the result of the operation, \
1501 without modifying the original"]
1502 #[inline]
1503 pub const fn checked_rem(self, rhs: Self) -> Option<Self> {
1504 if intrinsics::unlikely(rhs == 0) {
1505 None
1506 } else {
1507 // SAFETY: div by zero has been checked above and unsigned types have no other
1508 // failure modes for division
1509 Some(unsafe { intrinsics::unchecked_rem(self, rhs) })
1510 }
1511 }
1512
1513 /// Strict integer remainder. Computes `self % rhs`.
1514 ///
1515 /// Strict remainder calculation on unsigned types is just the regular
1516 /// remainder calculation. There's no way overflow could ever happen.
1517 /// This function exists so that all operations are accounted for in the
1518 /// strict operations.
1519 ///
1520 /// # Panics
1521 ///
1522 /// This function will panic if `rhs` is zero.
1523 ///
1524 /// # Examples
1525 ///
1526 /// ```
1527 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_rem(10), 0);")]
1528 /// ```
1529 ///
1530 /// The following panics because of division by zero:
1531 ///
1532 /// ```should_panic
1533 #[doc = concat!("let _ = 5", stringify!($SelfT), ".strict_rem(0);")]
1534 /// ```
1535 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1536 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1537 #[must_use = "this returns the result of the operation, \
1538 without modifying the original"]
1539 #[inline(always)]
1540 #[track_caller]
1541 pub const fn strict_rem(self, rhs: Self) -> Self {
1542 self % rhs
1543 }
1544
1545 /// Checked Euclidean modulo. Computes `self.rem_euclid(rhs)`, returning `None`
1546 /// if `rhs == 0`.
1547 ///
1548 /// # Examples
1549 ///
1550 /// ```
1551 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem_euclid(2), Some(1));")]
1552 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem_euclid(0), None);")]
1553 /// ```
1554 #[stable(feature = "euclidean_division", since = "1.38.0")]
1555 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
1556 #[must_use = "this returns the result of the operation, \
1557 without modifying the original"]
1558 #[inline]
1559 pub const fn checked_rem_euclid(self, rhs: Self) -> Option<Self> {
1560 if intrinsics::unlikely(rhs == 0) {
1561 None
1562 } else {
1563 Some(self.rem_euclid(rhs))
1564 }
1565 }
1566
1567 /// Strict Euclidean modulo. Computes `self.rem_euclid(rhs)`.
1568 ///
1569 /// Strict modulo calculation on unsigned types is just the regular
1570 /// remainder calculation. There's no way overflow could ever happen.
1571 /// This function exists so that all operations are accounted for in the
1572 /// strict operations. Since, for the positive integers, all common
1573 /// definitions of division are equal, this is exactly equal to
1574 /// `self.strict_rem(rhs)`.
1575 ///
1576 /// # Panics
1577 ///
1578 /// This function will panic if `rhs` is zero.
1579 ///
1580 /// # Examples
1581 ///
1582 /// ```
1583 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_rem_euclid(10), 0);")]
1584 /// ```
1585 ///
1586 /// The following panics because of division by zero:
1587 ///
1588 /// ```should_panic
1589 #[doc = concat!("let _ = 5", stringify!($SelfT), ".strict_rem_euclid(0);")]
1590 /// ```
1591 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1592 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1593 #[must_use = "this returns the result of the operation, \
1594 without modifying the original"]
1595 #[inline(always)]
1596 #[track_caller]
1597 pub const fn strict_rem_euclid(self, rhs: Self) -> Self {
1598 self % rhs
1599 }
1600
1601 /// Same value as `self | other`, but UB if any bit position is set in both inputs.
1602 ///
1603 /// This is a situational micro-optimization for places where you'd rather
1604 /// use addition on some platforms and bitwise or on other platforms, based
1605 /// on exactly which instructions combine better with whatever else you're
1606 /// doing. Note that there's no reason to bother using this for places
1607 /// where it's clear from the operations involved that they can't overlap.
1608 /// For example, if you're combining `u16`s into a `u32` with
1609 /// `((a as u32) << 16) | (b as u32)`, that's fine, as the backend will
1610 /// know those sides of the `|` are disjoint without needing help.
1611 ///
1612 /// # Examples
1613 ///
1614 /// ```
1615 /// #![feature(disjoint_bitor)]
1616 ///
1617 /// // SAFETY: `1` and `4` have no bits in common.
1618 /// unsafe {
1619 #[doc = concat!(" assert_eq!(1_", stringify!($SelfT), ".unchecked_disjoint_bitor(4), 5);")]
1620 /// }
1621 /// ```
1622 ///
1623 /// # Safety
1624 ///
1625 /// Requires that `(self & other) == 0`, otherwise it's immediate UB.
1626 ///
1627 /// Equivalently, requires that `(self | other) == (self + other)`.
1628 #[unstable(feature = "disjoint_bitor", issue = "135758")]
1629 #[rustc_const_unstable(feature = "disjoint_bitor", issue = "135758")]
1630 #[inline]
1631 pub const unsafe fn unchecked_disjoint_bitor(self, other: Self) -> Self {
1632 assert_unsafe_precondition!(
1633 check_language_ub,
1634 concat!(stringify!($SelfT), "::unchecked_disjoint_bitor cannot have overlapping bits"),
1635 (
1636 lhs: $SelfT = self,
1637 rhs: $SelfT = other,
1638 ) => (lhs & rhs) == 0,
1639 );
1640
1641 // SAFETY: Same precondition
1642 unsafe { intrinsics::disjoint_bitor(self, other) }
1643 }
1644
1645 /// Returns the logarithm of the number with respect to an arbitrary base,
1646 /// rounded down.
1647 ///
1648 /// This method might not be optimized owing to implementation details;
1649 /// `ilog2` can produce results more efficiently for base 2, and `ilog10`
1650 /// can produce results more efficiently for base 10.
1651 ///
1652 /// # Panics
1653 ///
1654 /// This function will panic if `self` is zero, or if `base` is less than 2.
1655 ///
1656 /// # Examples
1657 ///
1658 /// ```
1659 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".ilog(5), 1);")]
1660 /// ```
1661 #[stable(feature = "int_log", since = "1.67.0")]
1662 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1663 #[must_use = "this returns the result of the operation, \
1664 without modifying the original"]
1665 #[inline]
1666 #[track_caller]
1667 pub const fn ilog(self, base: Self) -> u32 {
1668 assert!(base >= 2, "base of integer logarithm must be at least 2");
1669 if let Some(log) = self.checked_ilog(base) {
1670 log
1671 } else {
1672 imp::int_log10::panic_for_nonpositive_argument()
1673 }
1674 }
1675
1676 /// Returns the base 2 logarithm of the number, rounded down.
1677 ///
1678 /// # Panics
1679 ///
1680 /// This function will panic if `self` is zero.
1681 ///
1682 /// # Examples
1683 ///
1684 /// ```
1685 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".ilog2(), 1);")]
1686 /// ```
1687 #[stable(feature = "int_log", since = "1.67.0")]
1688 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1689 #[must_use = "this returns the result of the operation, \
1690 without modifying the original"]
1691 #[inline]
1692 #[track_caller]
1693 pub const fn ilog2(self) -> u32 {
1694 if let Some(log) = self.checked_ilog2() {
1695 log
1696 } else {
1697 imp::int_log10::panic_for_nonpositive_argument()
1698 }
1699 }
1700
1701 /// Returns the base 10 logarithm of the number, rounded down.
1702 ///
1703 /// # Panics
1704 ///
1705 /// This function will panic if `self` is zero.
1706 ///
1707 /// # Example
1708 ///
1709 /// ```
1710 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".ilog10(), 1);")]
1711 /// ```
1712 #[stable(feature = "int_log", since = "1.67.0")]
1713 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1714 #[must_use = "this returns the result of the operation, \
1715 without modifying the original"]
1716 #[inline]
1717 #[track_caller]
1718 pub const fn ilog10(self) -> u32 {
1719 if let Some(log) = self.checked_ilog10() {
1720 log
1721 } else {
1722 imp::int_log10::panic_for_nonpositive_argument()
1723 }
1724 }
1725
1726 /// Returns the logarithm of the number with respect to an arbitrary base,
1727 /// rounded down.
1728 ///
1729 /// Returns `None` if the number is zero, or if the base is not at least 2.
1730 ///
1731 /// This method might not be optimized owing to implementation details;
1732 /// `checked_ilog2` can produce results more efficiently for base 2, and
1733 /// `checked_ilog10` can produce results more efficiently for base 10.
1734 ///
1735 /// # Examples
1736 ///
1737 /// ```
1738 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_ilog(5), Some(1));")]
1739 /// ```
1740 #[stable(feature = "int_log", since = "1.67.0")]
1741 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1742 #[must_use = "this returns the result of the operation, \
1743 without modifying the original"]
1744 #[inline]
1745 pub const fn checked_ilog(self, base: Self) -> Option<u32> {
1746 // Inform compiler of optimizations when the base is known at
1747 // compile time and there's a cheaper method available.
1748 //
1749 // Note: Like all optimizations, this is not guaranteed to be
1750 // applied by the compiler. If you want those specific bases,
1751 // use `.checked_ilog2()` or `.checked_ilog10()` directly.
1752 if core::intrinsics::is_val_statically_known(base) {
1753 if base == 2 {
1754 return self.checked_ilog2();
1755 } else if base == 10 {
1756 return self.checked_ilog10();
1757 }
1758 }
1759
1760 if self <= 0 || base <= 1 {
1761 None
1762 } else if self < base {
1763 Some(0)
1764 } else {
1765 // Since base >= self, n >= 1
1766 let mut n = 1;
1767 let mut r = base;
1768
1769 // Optimization for 128 bit wide integers.
1770 if Self::BITS == 128 {
1771 // The following is a correct lower bound for ⌊log(base,self)⌋ because
1772 //
1773 // log(base,self) = log(2,self) / log(2,base)
1774 // ≥ ⌊log(2,self)⌋ / (⌊log(2,base)⌋ + 1)
1775 //
1776 // hence
1777 //
1778 // ⌊log(base,self)⌋ ≥ ⌊ ⌊log(2,self)⌋ / (⌊log(2,base)⌋ + 1) ⌋ .
1779 n = self.ilog2() / (base.ilog2() + 1);
1780 r = base.pow(n);
1781 }
1782
1783 while r <= self / base {
1784 n += 1;
1785 r *= base;
1786 }
1787 Some(n)
1788 }
1789 }
1790
1791 /// Returns the base 2 logarithm of the number, rounded down.
1792 ///
1793 /// Returns `None` if the number is zero.
1794 ///
1795 /// # Examples
1796 ///
1797 /// ```
1798 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_ilog2(), Some(1));")]
1799 /// ```
1800 #[stable(feature = "int_log", since = "1.67.0")]
1801 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1802 #[must_use = "this returns the result of the operation, \
1803 without modifying the original"]
1804 #[inline]
1805 pub const fn checked_ilog2(self) -> Option<u32> {
1806 match NonZero::new(self) {
1807 Some(x) => Some(x.ilog2()),
1808 None => None,
1809 }
1810 }
1811
1812 /// Returns the base 10 logarithm of the number, rounded down.
1813 ///
1814 /// Returns `None` if the number is zero.
1815 ///
1816 /// # Examples
1817 ///
1818 /// ```
1819 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".checked_ilog10(), Some(1));")]
1820 /// ```
1821 #[stable(feature = "int_log", since = "1.67.0")]
1822 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1823 #[must_use = "this returns the result of the operation, \
1824 without modifying the original"]
1825 #[inline]
1826 pub const fn checked_ilog10(self) -> Option<u32> {
1827 match NonZero::new(self) {
1828 Some(x) => Some(x.ilog10()),
1829 None => None,
1830 }
1831 }
1832
1833 /// Checked negation. Computes `-self`, returning `None` unless `self ==
1834 /// 0`.
1835 ///
1836 /// Note that negating any positive integer will overflow.
1837 ///
1838 /// # Examples
1839 ///
1840 /// ```
1841 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_neg(), Some(0));")]
1842 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_neg(), None);")]
1843 /// ```
1844 #[stable(feature = "wrapping", since = "1.7.0")]
1845 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1846 #[must_use = "this returns the result of the operation, \
1847 without modifying the original"]
1848 #[inline]
1849 pub const fn checked_neg(self) -> Option<Self> {
1850 let (a, b) = self.overflowing_neg();
1851 if intrinsics::unlikely(b) { None } else { Some(a) }
1852 }
1853
1854 /// Strict negation. Computes `-self`, panicking unless `self ==
1855 /// 0`.
1856 ///
1857 /// Note that negating any positive integer will overflow.
1858 ///
1859 /// # Panics
1860 ///
1861 /// ## Overflow behavior
1862 ///
1863 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1864 ///
1865 /// # Examples
1866 ///
1867 /// ```
1868 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".strict_neg(), 0);")]
1869 /// ```
1870 ///
1871 /// The following panics because of overflow:
1872 ///
1873 /// ```should_panic
1874 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_neg();")]
1875 /// ```
1876 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1877 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1878 #[must_use = "this returns the result of the operation, \
1879 without modifying the original"]
1880 #[inline]
1881 #[track_caller]
1882 pub const fn strict_neg(self) -> Self {
1883 let (a, b) = self.overflowing_neg();
1884 if b { imp::overflow_panic::neg() } else { a }
1885 }
1886
1887 /// Checked shift left. Computes `self << rhs`, returning `None`
1888 /// if `rhs` is larger than or equal to the number of bits in `self`.
1889 ///
1890 /// # Examples
1891 ///
1892 /// ```
1893 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".checked_shl(4), Some(0x10));")]
1894 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shl(129), None);")]
1895 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shl(", stringify!($BITS_MINUS_ONE), "), Some(0));")]
1896 /// ```
1897 #[stable(feature = "wrapping", since = "1.7.0")]
1898 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1899 #[must_use = "this returns the result of the operation, \
1900 without modifying the original"]
1901 #[inline]
1902 pub const fn checked_shl(self, rhs: u32) -> Option<Self> {
1903 // Not using overflowing_shl as that's a wrapping shift
1904 if rhs < Self::BITS {
1905 // SAFETY: just checked the RHS is in-range
1906 Some(unsafe { self.unchecked_shl(rhs) })
1907 } else {
1908 None
1909 }
1910 }
1911
1912 /// Strict shift left. Computes `self << rhs`, panicking if `rhs` is larger
1913 /// than or equal to the number of bits in `self`.
1914 ///
1915 /// # Panics
1916 ///
1917 /// ## Overflow behavior
1918 ///
1919 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1920 ///
1921 /// # Examples
1922 ///
1923 /// ```
1924 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".strict_shl(4), 0x10);")]
1925 /// ```
1926 ///
1927 /// The following panics because of overflow:
1928 ///
1929 /// ```should_panic
1930 #[doc = concat!("let _ = 0x10", stringify!($SelfT), ".strict_shl(129);")]
1931 /// ```
1932 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1933 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1934 #[must_use = "this returns the result of the operation, \
1935 without modifying the original"]
1936 #[inline]
1937 #[track_caller]
1938 pub const fn strict_shl(self, rhs: u32) -> Self {
1939 let (a, b) = self.overflowing_shl(rhs);
1940 if b { imp::overflow_panic::shl() } else { a }
1941 }
1942
1943 /// Unchecked shift left. Computes `self << rhs`, assuming that
1944 /// `rhs` is less than the number of bits in `self`.
1945 ///
1946 /// # Safety
1947 ///
1948 /// This results in undefined behavior if `rhs` is larger than
1949 /// or equal to the number of bits in `self`,
1950 /// i.e. when [`checked_shl`] would return `None`.
1951 ///
1952 #[doc = concat!("[`checked_shl`]: ", stringify!($SelfT), "::checked_shl")]
1953 #[stable(feature = "unchecked_shifts", since = "1.93.0")]
1954 #[rustc_const_stable(feature = "unchecked_shifts", since = "1.93.0")]
1955 #[must_use = "this returns the result of the operation, \
1956 without modifying the original"]
1957 #[inline(always)]
1958 #[track_caller]
1959 pub const unsafe fn unchecked_shl(self, rhs: u32) -> Self {
1960 assert_unsafe_precondition!(
1961 check_language_ub,
1962 concat!(stringify!($SelfT), "::unchecked_shl cannot overflow"),
1963 (
1964 rhs: u32 = rhs,
1965 ) => rhs < <$ActualT>::BITS,
1966 );
1967
1968 // SAFETY: this is guaranteed to be safe by the caller.
1969 unsafe {
1970 intrinsics::unchecked_shl(self, rhs)
1971 }
1972 }
1973
1974 /// Unbounded shift left. Computes `self << rhs`, without bounding the value of `rhs`.
1975 ///
1976 /// If `rhs` is larger or equal to the number of bits in `self`,
1977 /// the entire value is shifted out, and `0` is returned.
1978 ///
1979 /// # Examples
1980 ///
1981 /// ```
1982 #[doc = concat!("assert_eq!(0x1_", stringify!($SelfT), ".unbounded_shl(4), 0x10);")]
1983 #[doc = concat!("assert_eq!(0x1_", stringify!($SelfT), ".unbounded_shl(129), 0);")]
1984 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(0), 0b101);")]
1985 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(1), 0b1010);")]
1986 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(2), 0b10100);")]
1987 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shl(", stringify!($BITS), "), 0);")]
1988 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shl(1).unbounded_shl(", stringify!($BITS_MINUS_ONE), "), 0);")]
1989 ///
1990 #[doc = concat!("let start : ", stringify!($SelfT), " = 13;")]
1991 /// let mut running = start;
1992 /// for i in 0..160 {
1993 /// // The unbounded shift left by i is the same as `<< 1` i times
1994 /// assert_eq!(running, start.unbounded_shl(i));
1995 /// // Which is not always the case for a wrapping shift
1996 #[doc = concat!(" assert_eq!(running == start.wrapping_shl(i), i < ", stringify!($BITS), ");")]
1997 ///
1998 /// running <<= 1;
1999 /// }
2000 /// ```
2001 #[stable(feature = "unbounded_shifts", since = "1.87.0")]
2002 #[rustc_const_stable(feature = "unbounded_shifts", since = "1.87.0")]
2003 #[must_use = "this returns the result of the operation, \
2004 without modifying the original"]
2005 #[inline]
2006 pub const fn unbounded_shl(self, rhs: u32) -> $SelfT{
2007 if rhs < Self::BITS {
2008 // SAFETY:
2009 // rhs is just checked to be in-range above
2010 unsafe { self.unchecked_shl(rhs) }
2011 } else {
2012 0
2013 }
2014 }
2015
2016 /// Exact shift left. Computes `self << rhs` as long as it can be reversed losslessly.
2017 ///
2018 /// Returns `None` if any non-zero bits would be shifted out or if `rhs` >=
2019 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2020 /// Otherwise, returns `Some(self << rhs)`.
2021 ///
2022 /// # Examples
2023 ///
2024 /// ```
2025 /// #![feature(exact_bitshifts)]
2026 ///
2027 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".shl_exact(4), Some(0x10));")]
2028 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".shl_exact(129), None);")]
2029 /// ```
2030 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2031 #[must_use = "this returns the result of the operation, \
2032 without modifying the original"]
2033 #[inline]
2034 pub const fn shl_exact(self, rhs: u32) -> Option<$SelfT> {
2035 if rhs <= self.leading_zeros() && rhs < <$SelfT>::BITS {
2036 // SAFETY: rhs is checked above
2037 Some(unsafe { self.unchecked_shl(rhs) })
2038 } else {
2039 None
2040 }
2041 }
2042
2043 /// Unchecked exact shift left. Computes `self << rhs`, assuming the operation can be
2044 /// losslessly reversed `rhs` cannot be larger than
2045 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2046 ///
2047 /// # Safety
2048 ///
2049 /// This results in undefined behavior when `rhs > self.leading_zeros() || rhs >=
2050 #[doc = concat!(stringify!($SelfT), "::BITS`")]
2051 /// i.e. when
2052 #[doc = concat!("[`", stringify!($SelfT), "::shl_exact`]")]
2053 /// would return `None`.
2054 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2055 #[must_use = "this returns the result of the operation, \
2056 without modifying the original"]
2057 #[inline]
2058 pub const unsafe fn unchecked_shl_exact(self, rhs: u32) -> $SelfT {
2059 assert_unsafe_precondition!(
2060 check_library_ub,
2061 concat!(stringify!($SelfT), "::unchecked_shl_exact cannot shift out non-zero bits"),
2062 (
2063 zeros: u32 = self.leading_zeros(),
2064 bits: u32 = <$SelfT>::BITS,
2065 rhs: u32 = rhs,
2066 ) => rhs <= zeros && rhs < bits,
2067 );
2068
2069 // SAFETY: this is guaranteed to be safe by the caller
2070 unsafe { self.unchecked_shl(rhs) }
2071 }
2072
2073 /// Checked shift right. Computes `self >> rhs`, returning `None`
2074 /// if `rhs` is larger than or equal to the number of bits in `self`.
2075 ///
2076 /// # Examples
2077 ///
2078 /// ```
2079 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shr(4), Some(0x1));")]
2080 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shr(129), None);")]
2081 /// ```
2082 #[stable(feature = "wrapping", since = "1.7.0")]
2083 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
2084 #[must_use = "this returns the result of the operation, \
2085 without modifying the original"]
2086 #[inline]
2087 pub const fn checked_shr(self, rhs: u32) -> Option<Self> {
2088 // Not using overflowing_shr as that's a wrapping shift
2089 if rhs < Self::BITS {
2090 // SAFETY: just checked the RHS is in-range
2091 Some(unsafe { self.unchecked_shr(rhs) })
2092 } else {
2093 None
2094 }
2095 }
2096
2097 /// Strict shift right. Computes `self >> rhs`, panicking if `rhs` is
2098 /// larger than or equal to the number of bits in `self`.
2099 ///
2100 /// # Panics
2101 ///
2102 /// ## Overflow behavior
2103 ///
2104 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2105 ///
2106 /// # Examples
2107 ///
2108 /// ```
2109 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".strict_shr(4), 0x1);")]
2110 /// ```
2111 ///
2112 /// The following panics because of overflow:
2113 ///
2114 /// ```should_panic
2115 #[doc = concat!("let _ = 0x10", stringify!($SelfT), ".strict_shr(129);")]
2116 /// ```
2117 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2118 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2119 #[must_use = "this returns the result of the operation, \
2120 without modifying the original"]
2121 #[inline]
2122 #[track_caller]
2123 pub const fn strict_shr(self, rhs: u32) -> Self {
2124 let (a, b) = self.overflowing_shr(rhs);
2125 if b { imp::overflow_panic::shr() } else { a }
2126 }
2127
2128 /// Unchecked shift right. Computes `self >> rhs`, assuming that
2129 /// `rhs` is less than the number of bits in `self`.
2130 ///
2131 /// # Safety
2132 ///
2133 /// This results in undefined behavior if `rhs` is larger than
2134 /// or equal to the number of bits in `self`,
2135 /// i.e. when [`checked_shr`] would return `None`.
2136 ///
2137 #[doc = concat!("[`checked_shr`]: ", stringify!($SelfT), "::checked_shr")]
2138 #[stable(feature = "unchecked_shifts", since = "1.93.0")]
2139 #[rustc_const_stable(feature = "unchecked_shifts", since = "1.93.0")]
2140 #[must_use = "this returns the result of the operation, \
2141 without modifying the original"]
2142 #[inline(always)]
2143 #[track_caller]
2144 pub const unsafe fn unchecked_shr(self, rhs: u32) -> Self {
2145 assert_unsafe_precondition!(
2146 check_language_ub,
2147 concat!(stringify!($SelfT), "::unchecked_shr cannot overflow"),
2148 (
2149 rhs: u32 = rhs,
2150 ) => rhs < <$ActualT>::BITS,
2151 );
2152
2153 // SAFETY: this is guaranteed to be safe by the caller.
2154 unsafe {
2155 intrinsics::unchecked_shr(self, rhs)
2156 }
2157 }
2158
2159 /// Unbounded shift right. Computes `self >> rhs`, without bounding the value of `rhs`.
2160 ///
2161 /// If `rhs` is larger or equal to the number of bits in `self`,
2162 /// the entire value is shifted out, and `0` is returned.
2163 ///
2164 /// # Examples
2165 ///
2166 /// ```
2167 #[doc = concat!("assert_eq!(0x10_", stringify!($SelfT), ".unbounded_shr(4), 0x1);")]
2168 #[doc = concat!("assert_eq!(0x10_", stringify!($SelfT), ".unbounded_shr(129), 0);")]
2169 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(0), 0b1010);")]
2170 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(1), 0b101);")]
2171 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(2), 0b10);")]
2172 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shr(", stringify!($BITS), "), 0);")]
2173 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shr(1).unbounded_shr(", stringify!($BITS_MINUS_ONE), "), 0);")]
2174 ///
2175 #[doc = concat!("let start = ", stringify!($SelfT), "::rotate_right(13, 4);")]
2176 /// let mut running = start;
2177 /// for i in 0..160 {
2178 /// // The unbounded shift right by i is the same as `>> 1` i times
2179 /// assert_eq!(running, start.unbounded_shr(i));
2180 /// // Which is not always the case for a wrapping shift
2181 #[doc = concat!(" assert_eq!(running == start.wrapping_shr(i), i < ", stringify!($BITS), ");")]
2182 ///
2183 /// running >>= 1;
2184 /// }
2185 /// ```
2186 #[stable(feature = "unbounded_shifts", since = "1.87.0")]
2187 #[rustc_const_stable(feature = "unbounded_shifts", since = "1.87.0")]
2188 #[must_use = "this returns the result of the operation, \
2189 without modifying the original"]
2190 #[inline]
2191 pub const fn unbounded_shr(self, rhs: u32) -> $SelfT{
2192 if rhs < Self::BITS {
2193 // SAFETY:
2194 // rhs is just checked to be in-range above
2195 unsafe { self.unchecked_shr(rhs) }
2196 } else {
2197 0
2198 }
2199 }
2200
2201 /// Exact shift right. Computes `self >> rhs` as long as it can be reversed losslessly.
2202 ///
2203 /// Returns `None` if any non-zero bits would be shifted out or if `rhs` >=
2204 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2205 /// Otherwise, returns `Some(self >> rhs)`.
2206 ///
2207 /// # Examples
2208 ///
2209 /// ```
2210 /// #![feature(exact_bitshifts)]
2211 ///
2212 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".shr_exact(4), Some(0x1));")]
2213 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".shr_exact(5), None);")]
2214 /// ```
2215 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2216 #[must_use = "this returns the result of the operation, \
2217 without modifying the original"]
2218 #[inline]
2219 pub const fn shr_exact(self, rhs: u32) -> Option<$SelfT> {
2220 if rhs <= self.trailing_zeros() && rhs < <$SelfT>::BITS {
2221 // SAFETY: rhs is checked above
2222 Some(unsafe { self.unchecked_shr(rhs) })
2223 } else {
2224 None
2225 }
2226 }
2227
2228 /// Unchecked exact shift right. Computes `self >> rhs`, assuming the operation can be
2229 /// losslessly reversed and `rhs` cannot be larger than
2230 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2231 ///
2232 /// # Safety
2233 ///
2234 /// This results in undefined behavior when `rhs > self.trailing_zeros() || rhs >=
2235 #[doc = concat!(stringify!($SelfT), "::BITS`")]
2236 /// i.e. when
2237 #[doc = concat!("[`", stringify!($SelfT), "::shr_exact`]")]
2238 /// would return `None`.
2239 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2240 #[must_use = "this returns the result of the operation, \
2241 without modifying the original"]
2242 #[inline]
2243 pub const unsafe fn unchecked_shr_exact(self, rhs: u32) -> $SelfT {
2244 assert_unsafe_precondition!(
2245 check_library_ub,
2246 concat!(stringify!($SelfT), "::unchecked_shr_exact cannot shift out non-zero bits"),
2247 (
2248 zeros: u32 = self.trailing_zeros(),
2249 bits: u32 = <$SelfT>::BITS,
2250 rhs: u32 = rhs,
2251 ) => rhs <= zeros && rhs < bits,
2252 );
2253
2254 // SAFETY: this is guaranteed to be safe by the caller
2255 unsafe { self.unchecked_shr(rhs) }
2256 }
2257
2258 /// Checked exponentiation. Computes `self.pow(exp)`, returning `None` if
2259 /// overflow occurred.
2260 ///
2261 /// # Examples
2262 ///
2263 /// ```
2264 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_pow(5), Some(32));")]
2265 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".checked_pow(0), Some(1));")]
2266 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_pow(2), None);")]
2267 /// ```
2268 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2269 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2270 #[must_use = "this returns the result of the operation, \
2271 without modifying the original"]
2272 #[inline]
2273 pub const fn checked_pow(self, mut exp: u32) -> Option<Self> {
2274 if exp == 0 {
2275 return Some(1);
2276 }
2277 let mut base = self;
2278 let mut acc: Self = 1;
2279
2280 loop {
2281 if (exp & 1) == 1 {
2282 acc = try_opt!(acc.checked_mul(base));
2283 // since exp!=0, finally the exp must be 1.
2284 if exp == 1 {
2285 return Some(acc);
2286 }
2287 }
2288 exp /= 2;
2289 base = try_opt!(base.checked_mul(base));
2290 }
2291 }
2292
2293 /// Strict exponentiation. Computes `self.pow(exp)`, panicking if
2294 /// overflow occurred.
2295 ///
2296 /// # Panics
2297 ///
2298 /// ## Overflow behavior
2299 ///
2300 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2301 ///
2302 /// # Examples
2303 ///
2304 /// ```
2305 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".strict_pow(5), 32);")]
2306 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".strict_pow(0), 1);")]
2307 /// ```
2308 ///
2309 /// The following panics because of overflow:
2310 ///
2311 /// ```should_panic
2312 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_pow(2);")]
2313 /// ```
2314 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2315 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2316 #[must_use = "this returns the result of the operation, \
2317 without modifying the original"]
2318 #[inline]
2319 #[track_caller]
2320 pub const fn strict_pow(self, mut exp: u32) -> Self {
2321 if exp == 0 {
2322 return 1;
2323 }
2324 let mut base = self;
2325 let mut acc: Self = 1;
2326
2327 loop {
2328 if (exp & 1) == 1 {
2329 acc = acc.strict_mul(base);
2330 // since exp!=0, finally the exp must be 1.
2331 if exp == 1 {
2332 return acc;
2333 }
2334 }
2335 exp /= 2;
2336 base = base.strict_mul(base);
2337 }
2338 }
2339
2340 /// Saturating integer addition. Computes `self + rhs`, saturating at
2341 /// the numeric bounds instead of overflowing.
2342 ///
2343 /// # Examples
2344 ///
2345 /// ```
2346 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".saturating_add(1), 101);")]
2347 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.saturating_add(127), ", stringify!($SelfT), "::MAX);")]
2348 /// ```
2349 #[stable(feature = "rust1", since = "1.0.0")]
2350 #[must_use = "this returns the result of the operation, \
2351 without modifying the original"]
2352 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2353 #[inline(always)]
2354 pub const fn saturating_add(self, rhs: Self) -> Self {
2355 intrinsics::saturating_add(self, rhs)
2356 }
2357
2358 /// Saturating addition with a signed integer. Computes `self + rhs`,
2359 /// saturating at the numeric bounds instead of overflowing.
2360 ///
2361 /// # Examples
2362 ///
2363 /// ```
2364 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_add_signed(2), 3);")]
2365 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_add_signed(-2), 0);")]
2366 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).saturating_add_signed(4), ", stringify!($SelfT), "::MAX);")]
2367 /// ```
2368 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
2369 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
2370 #[must_use = "this returns the result of the operation, \
2371 without modifying the original"]
2372 #[inline]
2373 pub const fn saturating_add_signed(self, rhs: $SignedT) -> Self {
2374 let (res, overflow) = self.overflowing_add(rhs as Self);
2375 if overflow == (rhs < 0) {
2376 res
2377 } else if overflow {
2378 Self::MAX
2379 } else {
2380 0
2381 }
2382 }
2383
2384 /// Saturating integer subtraction. Computes `self - rhs`, saturating
2385 /// at the numeric bounds instead of overflowing.
2386 ///
2387 /// # Examples
2388 ///
2389 /// ```
2390 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".saturating_sub(27), 73);")]
2391 #[doc = concat!("assert_eq!(13", stringify!($SelfT), ".saturating_sub(127), 0);")]
2392 /// ```
2393 #[stable(feature = "rust1", since = "1.0.0")]
2394 #[must_use = "this returns the result of the operation, \
2395 without modifying the original"]
2396 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2397 #[inline(always)]
2398 pub const fn saturating_sub(self, rhs: Self) -> Self {
2399 intrinsics::saturating_sub(self, rhs)
2400 }
2401
2402 /// Saturating integer subtraction. Computes `self` - `rhs`, saturating at
2403 /// the numeric bounds instead of overflowing.
2404 ///
2405 /// # Examples
2406 ///
2407 /// ```
2408 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_sub_signed(2), 0);")]
2409 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_sub_signed(-2), 3);")]
2410 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).saturating_sub_signed(-4), ", stringify!($SelfT), "::MAX);")]
2411 /// ```
2412 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2413 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2414 #[must_use = "this returns the result of the operation, \
2415 without modifying the original"]
2416 #[inline]
2417 pub const fn saturating_sub_signed(self, rhs: $SignedT) -> Self {
2418 let (res, overflow) = self.overflowing_sub_signed(rhs);
2419
2420 if !overflow {
2421 res
2422 } else if rhs < 0 {
2423 Self::MAX
2424 } else {
2425 0
2426 }
2427 }
2428
2429 /// Saturating integer multiplication. Computes `self * rhs`,
2430 /// saturating at the numeric bounds instead of overflowing.
2431 ///
2432 /// # Examples
2433 ///
2434 /// ```
2435 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".saturating_mul(10), 20);")]
2436 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX).saturating_mul(10), ", stringify!($SelfT),"::MAX);")]
2437 /// ```
2438 #[stable(feature = "wrapping", since = "1.7.0")]
2439 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2440 #[must_use = "this returns the result of the operation, \
2441 without modifying the original"]
2442 #[inline]
2443 pub const fn saturating_mul(self, rhs: Self) -> Self {
2444 match self.checked_mul(rhs) {
2445 Some(x) => x,
2446 None => Self::MAX,
2447 }
2448 }
2449
2450 /// Saturating integer division. Computes `self / rhs`, saturating at the
2451 /// numeric bounds instead of overflowing.
2452 ///
2453 /// # Panics
2454 ///
2455 /// This function will panic if `rhs` is zero.
2456 ///
2457 /// # Examples
2458 ///
2459 /// ```
2460 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".saturating_div(2), 2);")]
2461 ///
2462 /// ```
2463 #[stable(feature = "saturating_div", since = "1.58.0")]
2464 #[rustc_const_stable(feature = "saturating_div", since = "1.58.0")]
2465 #[must_use = "this returns the result of the operation, \
2466 without modifying the original"]
2467 #[inline]
2468 #[track_caller]
2469 pub const fn saturating_div(self, rhs: Self) -> Self {
2470 // on unsigned types, there is no overflow in integer division
2471 self.wrapping_div(rhs)
2472 }
2473
2474 /// Saturating integer exponentiation. Computes `self.pow(exp)`,
2475 /// saturating at the numeric bounds instead of overflowing.
2476 ///
2477 /// # Examples
2478 ///
2479 /// ```
2480 #[doc = concat!("assert_eq!(4", stringify!($SelfT), ".saturating_pow(3), 64);")]
2481 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".saturating_pow(0), 1);")]
2482 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.saturating_pow(2), ", stringify!($SelfT), "::MAX);")]
2483 /// ```
2484 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2485 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2486 #[must_use = "this returns the result of the operation, \
2487 without modifying the original"]
2488 #[inline]
2489 pub const fn saturating_pow(self, exp: u32) -> Self {
2490 match self.checked_pow(exp) {
2491 Some(x) => x,
2492 None => Self::MAX,
2493 }
2494 }
2495
2496 /// Wrapping (modular) addition. Computes `self + rhs`,
2497 /// wrapping around at the boundary of the type.
2498 ///
2499 /// # Examples
2500 ///
2501 /// ```
2502 #[doc = concat!("assert_eq!(200", stringify!($SelfT), ".wrapping_add(55), 255);")]
2503 #[doc = concat!("assert_eq!(200", stringify!($SelfT), ".wrapping_add(", stringify!($SelfT), "::MAX), 199);")]
2504 /// ```
2505 #[stable(feature = "rust1", since = "1.0.0")]
2506 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2507 #[must_use = "this returns the result of the operation, \
2508 without modifying the original"]
2509 #[inline(always)]
2510 pub const fn wrapping_add(self, rhs: Self) -> Self {
2511 intrinsics::wrapping_add(self, rhs)
2512 }
2513
2514 /// Wrapping (modular) addition with a signed integer. Computes
2515 /// `self + rhs`, wrapping around at the boundary of the type.
2516 ///
2517 /// # Examples
2518 ///
2519 /// ```
2520 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_add_signed(2), 3);")]
2521 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_add_signed(-2), ", stringify!($SelfT), "::MAX);")]
2522 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).wrapping_add_signed(4), 1);")]
2523 /// ```
2524 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
2525 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
2526 #[must_use = "this returns the result of the operation, \
2527 without modifying the original"]
2528 #[inline]
2529 pub const fn wrapping_add_signed(self, rhs: $SignedT) -> Self {
2530 self.wrapping_add(rhs as Self)
2531 }
2532
2533 /// Wrapping (modular) subtraction. Computes `self - rhs`,
2534 /// wrapping around at the boundary of the type.
2535 ///
2536 /// # Examples
2537 ///
2538 /// ```
2539 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_sub(100), 0);")]
2540 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_sub(", stringify!($SelfT), "::MAX), 101);")]
2541 /// ```
2542 #[stable(feature = "rust1", since = "1.0.0")]
2543 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2544 #[must_use = "this returns the result of the operation, \
2545 without modifying the original"]
2546 #[inline(always)]
2547 pub const fn wrapping_sub(self, rhs: Self) -> Self {
2548 intrinsics::wrapping_sub(self, rhs)
2549 }
2550
2551 /// Wrapping (modular) subtraction with a signed integer. Computes
2552 /// `self - rhs`, wrapping around at the boundary of the type.
2553 ///
2554 /// # Examples
2555 ///
2556 /// ```
2557 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_sub_signed(2), ", stringify!($SelfT), "::MAX);")]
2558 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_sub_signed(-2), 3);")]
2559 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).wrapping_sub_signed(-4), 1);")]
2560 /// ```
2561 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2562 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2563 #[must_use = "this returns the result of the operation, \
2564 without modifying the original"]
2565 #[inline]
2566 pub const fn wrapping_sub_signed(self, rhs: $SignedT) -> Self {
2567 self.wrapping_sub(rhs as Self)
2568 }
2569
2570 /// Wrapping (modular) multiplication. Computes `self *
2571 /// rhs`, wrapping around at the boundary of the type.
2572 ///
2573 /// # Examples
2574 ///
2575 /// Please note that this example is shared among integer types, which is why `u8` is used.
2576 ///
2577 /// ```
2578 /// assert_eq!(10u8.wrapping_mul(12), 120);
2579 /// assert_eq!(25u8.wrapping_mul(12), 44);
2580 /// ```
2581 #[stable(feature = "rust1", since = "1.0.0")]
2582 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2583 #[must_use = "this returns the result of the operation, \
2584 without modifying the original"]
2585 #[inline(always)]
2586 pub const fn wrapping_mul(self, rhs: Self) -> Self {
2587 intrinsics::wrapping_mul(self, rhs)
2588 }
2589
2590 /// Wrapping (modular) division. Computes `self / rhs`.
2591 ///
2592 /// Wrapped division on unsigned types is just normal division. There's
2593 /// no way wrapping could ever happen. This function exists so that all
2594 /// operations are accounted for in the wrapping operations.
2595 ///
2596 /// # Panics
2597 ///
2598 /// This function will panic if `rhs` is zero.
2599 ///
2600 /// # Examples
2601 ///
2602 /// ```
2603 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_div(10), 10);")]
2604 /// ```
2605 #[stable(feature = "num_wrapping", since = "1.2.0")]
2606 #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.52.0")]
2607 #[must_use = "this returns the result of the operation, \
2608 without modifying the original"]
2609 #[inline(always)]
2610 #[track_caller]
2611 pub const fn wrapping_div(self, rhs: Self) -> Self {
2612 self / rhs
2613 }
2614
2615 /// Wrapping Euclidean division. Computes `self.div_euclid(rhs)`.
2616 ///
2617 /// Wrapped division on unsigned types is just normal division. There's
2618 /// no way wrapping could ever happen. This function exists so that all
2619 /// operations are accounted for in the wrapping operations. Since, for
2620 /// the positive integers, all common definitions of division are equal,
2621 /// this is exactly equal to `self.wrapping_div(rhs)`.
2622 ///
2623 /// # Panics
2624 ///
2625 /// This function will panic if `rhs` is zero.
2626 ///
2627 /// # Examples
2628 ///
2629 /// ```
2630 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_div_euclid(10), 10);")]
2631 /// ```
2632 #[stable(feature = "euclidean_division", since = "1.38.0")]
2633 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
2634 #[must_use = "this returns the result of the operation, \
2635 without modifying the original"]
2636 #[inline(always)]
2637 #[track_caller]
2638 pub const fn wrapping_div_euclid(self, rhs: Self) -> Self {
2639 self / rhs
2640 }
2641
2642 /// Wrapping (modular) remainder. Computes `self % rhs`.
2643 ///
2644 /// Wrapped remainder calculation on unsigned types is just the regular
2645 /// remainder calculation. There's no way wrapping could ever happen.
2646 /// This function exists so that all operations are accounted for in the
2647 /// wrapping operations.
2648 ///
2649 /// # Panics
2650 ///
2651 /// This function will panic if `rhs` is zero.
2652 ///
2653 /// # Examples
2654 ///
2655 /// ```
2656 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_rem(10), 0);")]
2657 /// ```
2658 #[stable(feature = "num_wrapping", since = "1.2.0")]
2659 #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.52.0")]
2660 #[must_use = "this returns the result of the operation, \
2661 without modifying the original"]
2662 #[inline(always)]
2663 #[track_caller]
2664 pub const fn wrapping_rem(self, rhs: Self) -> Self {
2665 self % rhs
2666 }
2667
2668 /// Wrapping Euclidean modulo. Computes `self.rem_euclid(rhs)`.
2669 ///
2670 /// Wrapped modulo calculation on unsigned types is just the regular
2671 /// remainder calculation. There's no way wrapping could ever happen.
2672 /// This function exists so that all operations are accounted for in the
2673 /// wrapping operations. Since, for the positive integers, all common
2674 /// definitions of division are equal, this is exactly equal to
2675 /// `self.wrapping_rem(rhs)`.
2676 ///
2677 /// # Panics
2678 ///
2679 /// This function will panic if `rhs` is zero.
2680 ///
2681 /// # Examples
2682 ///
2683 /// ```
2684 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_rem_euclid(10), 0);")]
2685 /// ```
2686 #[stable(feature = "euclidean_division", since = "1.38.0")]
2687 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
2688 #[must_use = "this returns the result of the operation, \
2689 without modifying the original"]
2690 #[inline(always)]
2691 #[track_caller]
2692 pub const fn wrapping_rem_euclid(self, rhs: Self) -> Self {
2693 self % rhs
2694 }
2695
2696 /// Wrapping (modular) negation. Computes `-self`,
2697 /// wrapping around at the boundary of the type.
2698 ///
2699 /// Since unsigned types do not have negative equivalents
2700 /// all applications of this function will wrap (except for `-0`).
2701 /// For values smaller than the corresponding signed type's maximum
2702 /// the result is the same as casting the corresponding signed value.
2703 /// Any larger values are equivalent to `MAX + 1 - (val - MAX - 1)` where
2704 /// `MAX` is the corresponding signed type's maximum.
2705 ///
2706 /// # Examples
2707 ///
2708 /// ```
2709 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".wrapping_neg(), 0);")]
2710 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_neg(), 1);")]
2711 #[doc = concat!("assert_eq!(13_", stringify!($SelfT), ".wrapping_neg(), (!13) + 1);")]
2712 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_neg(), !(42 - 1));")]
2713 /// ```
2714 #[stable(feature = "num_wrapping", since = "1.2.0")]
2715 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2716 #[must_use = "this returns the result of the operation, \
2717 without modifying the original"]
2718 #[inline(always)]
2719 pub const fn wrapping_neg(self) -> Self {
2720 (0 as $SelfT).wrapping_sub(self)
2721 }
2722
2723 /// Panic-free bitwise shift-left; yields `self << mask(rhs)`,
2724 /// where `mask` removes any high-order bits of `rhs` that
2725 /// would cause the shift to exceed the bitwidth of the type.
2726 ///
2727 /// Beware that, unlike most other `wrapping_*` methods on integers, this
2728 /// does *not* give the same result as doing the shift in infinite precision
2729 /// then truncating as needed. The behaviour matches what shift instructions
2730 /// do on many processors, and is what the `<<` operator does when overflow
2731 /// checks are disabled, but numerically it's weird. Consider, instead,
2732 /// using [`Self::unbounded_shl`] which has nicer behaviour.
2733 ///
2734 /// Note that this is *not* the same as a rotate-left; the
2735 /// RHS of a wrapping shift-left is restricted to the range
2736 /// of the type, rather than the bits shifted out of the LHS
2737 /// being returned to the other end. The primitive integer
2738 /// types all implement a [`rotate_left`](Self::rotate_left) function,
2739 /// which may be what you want instead.
2740 ///
2741 /// # Examples
2742 ///
2743 /// ```
2744 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".wrapping_shl(7), 128);")]
2745 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(0), 0b101);")]
2746 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(1), 0b1010);")]
2747 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(2), 0b10100);")]
2748 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_shl(2), ", stringify!($SelfT), "::MAX - 3);")]
2749 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shl(", stringify!($BITS), "), 42);")]
2750 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shl(1).wrapping_shl(", stringify!($BITS_MINUS_ONE), "), 0);")]
2751 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".wrapping_shl(128), 1);")]
2752 #[doc = concat!("assert_eq!(5_", stringify!($SelfT), ".wrapping_shl(1025), 10);")]
2753 /// ```
2754 #[stable(feature = "num_wrapping", since = "1.2.0")]
2755 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2756 #[must_use = "this returns the result of the operation, \
2757 without modifying the original"]
2758 #[inline(always)]
2759 pub const fn wrapping_shl(self, rhs: u32) -> Self {
2760 // SAFETY: the masking by the bitsize of the type ensures that we do not shift
2761 // out of bounds
2762 unsafe {
2763 self.unchecked_shl(rhs & (Self::BITS - 1))
2764 }
2765 }
2766
2767 /// Panic-free bitwise shift-right; yields `self >> mask(rhs)`,
2768 /// where `mask` removes any high-order bits of `rhs` that
2769 /// would cause the shift to exceed the bitwidth of the type.
2770 ///
2771 /// Beware that, unlike most other `wrapping_*` methods on integers, this
2772 /// does *not* give the same result as doing the shift in infinite precision
2773 /// then truncating as needed. The behaviour matches what shift instructions
2774 /// do on many processors, and is what the `>>` operator does when overflow
2775 /// checks are disabled, but numerically it's weird. Consider, instead,
2776 /// using [`Self::unbounded_shr`] which has nicer behaviour.
2777 ///
2778 /// Note that this is *not* the same as a rotate-right; the
2779 /// RHS of a wrapping shift-right is restricted to the range
2780 /// of the type, rather than the bits shifted out of the LHS
2781 /// being returned to the other end. The primitive integer
2782 /// types all implement a [`rotate_right`](Self::rotate_right) function,
2783 /// which may be what you want instead.
2784 ///
2785 /// # Examples
2786 ///
2787 /// ```
2788 #[doc = concat!("assert_eq!(128_", stringify!($SelfT), ".wrapping_shr(7), 1);")]
2789 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(0), 0b1010);")]
2790 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(1), 0b101);")]
2791 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(2), 0b10);")]
2792 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_shr(1), ", stringify!($SignedT), "::MAX.cast_unsigned());")]
2793 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shr(", stringify!($BITS), "), 42);")]
2794 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shr(1).wrapping_shr(", stringify!($BITS_MINUS_ONE), "), 0);")]
2795 #[doc = concat!("assert_eq!(128_", stringify!($SelfT), ".wrapping_shr(128), 128);")]
2796 #[doc = concat!("assert_eq!(10_", stringify!($SelfT), ".wrapping_shr(1025), 5);")]
2797 /// ```
2798 #[stable(feature = "num_wrapping", since = "1.2.0")]
2799 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2800 #[must_use = "this returns the result of the operation, \
2801 without modifying the original"]
2802 #[inline(always)]
2803 pub const fn wrapping_shr(self, rhs: u32) -> Self {
2804 // SAFETY: the masking by the bitsize of the type ensures that we do not shift
2805 // out of bounds
2806 unsafe {
2807 self.unchecked_shr(rhs & (Self::BITS - 1))
2808 }
2809 }
2810
2811 /// Wrapping (modular) exponentiation. Computes `self.pow(exp)`,
2812 /// wrapping around at the boundary of the type.
2813 ///
2814 /// # Examples
2815 ///
2816 /// ```
2817 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".wrapping_pow(5), 243);")]
2818 /// assert_eq!(3u8.wrapping_pow(6), 217);
2819 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".wrapping_pow(0), 1);")]
2820 /// ```
2821 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2822 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2823 #[must_use = "this returns the result of the operation, \
2824 without modifying the original"]
2825 #[inline]
2826 pub const fn wrapping_pow(self, mut exp: u32) -> Self {
2827 if exp == 0 {
2828 return 1;
2829 }
2830 let mut base = self;
2831 let mut acc: Self = 1;
2832
2833 if intrinsics::is_val_statically_known(exp) {
2834 while exp > 1 {
2835 if (exp & 1) == 1 {
2836 acc = acc.wrapping_mul(base);
2837 }
2838 exp /= 2;
2839 base = base.wrapping_mul(base);
2840 }
2841
2842 // since exp!=0, finally the exp must be 1.
2843 // Deal with the final bit of the exponent separately, since
2844 // squaring the base afterwards is not necessary.
2845 acc.wrapping_mul(base)
2846 } else {
2847 // This is faster than the above when the exponent is not known
2848 // at compile time. We can't use the same code for the constant
2849 // exponent case because LLVM is currently unable to unroll
2850 // this loop.
2851 loop {
2852 if (exp & 1) == 1 {
2853 acc = acc.wrapping_mul(base);
2854 // since exp!=0, finally the exp must be 1.
2855 if exp == 1 {
2856 return acc;
2857 }
2858 }
2859 exp /= 2;
2860 base = base.wrapping_mul(base);
2861 }
2862 }
2863 }
2864
2865 /// Calculates `self` + `rhs`.
2866 ///
2867 /// Returns a tuple of the addition along with a boolean indicating
2868 /// whether an arithmetic overflow would occur. If an overflow would
2869 /// have occurred then the wrapped value is returned.
2870 ///
2871 /// # Examples
2872 ///
2873 /// ```
2874 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_add(2), (7, false));")]
2875 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.overflowing_add(1), (0, true));")]
2876 /// ```
2877 #[stable(feature = "wrapping", since = "1.7.0")]
2878 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2879 #[must_use = "this returns the result of the operation, \
2880 without modifying the original"]
2881 #[inline(always)]
2882 pub const fn overflowing_add(self, rhs: Self) -> (Self, bool) {
2883 let (a, b) = intrinsics::add_with_overflow(self as $ActualT, rhs as $ActualT);
2884 (a as Self, b)
2885 }
2886
2887 /// Calculates `self` + `rhs` + `carry` and returns a tuple containing
2888 /// the sum and the output carry (in that order).
2889 ///
2890 /// Performs "ternary addition" of two integer operands and a carry-in
2891 /// bit, and returns an output integer and a carry-out bit. This allows
2892 /// chaining together multiple additions to create a wider addition, and
2893 /// can be useful for bignum addition.
2894 ///
2895 #[doc = concat!("This can be thought of as a ", stringify!($BITS), "-bit \"full adder\", in the electronics sense.")]
2896 ///
2897 /// If the input carry is false, this method is equivalent to
2898 /// [`overflowing_add`](Self::overflowing_add), and the output carry is
2899 /// equal to the overflow flag. Note that although carry and overflow
2900 /// flags are similar for unsigned integers, they are different for
2901 /// signed integers.
2902 ///
2903 /// # Examples
2904 ///
2905 /// ```
2906 #[doc = concat!("// 3 MAX (a = 3 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")]
2907 #[doc = concat!("// + 5 7 (b = 5 × 2^", stringify!($BITS), " + 7)")]
2908 /// // ---------
2909 #[doc = concat!("// 9 6 (sum = 9 × 2^", stringify!($BITS), " + 6)")]
2910 ///
2911 #[doc = concat!("let (a1, a0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (3, ", stringify!($SelfT), "::MAX);")]
2912 #[doc = concat!("let (b1, b0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (5, 7);")]
2913 /// let carry0 = false;
2914 ///
2915 /// let (sum0, carry1) = a0.carrying_add(b0, carry0);
2916 /// assert_eq!(carry1, true);
2917 /// let (sum1, carry2) = a1.carrying_add(b1, carry1);
2918 /// assert_eq!(carry2, false);
2919 ///
2920 /// assert_eq!((sum1, sum0), (9, 6));
2921 /// ```
2922 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
2923 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
2924 #[must_use = "this returns the result of the operation, \
2925 without modifying the original"]
2926 #[inline]
2927 pub const fn carrying_add(self, rhs: Self, carry: bool) -> (Self, bool) {
2928 // note: longer-term this should be done via an intrinsic, but this has been shown
2929 // to generate optimal code for now, and LLVM doesn't have an equivalent intrinsic
2930 let (a, c1) = self.overflowing_add(rhs);
2931 let (b, c2) = a.overflowing_add(carry as $SelfT);
2932 // Ideally LLVM would know this is disjoint without us telling them,
2933 // but it doesn't <https://github.com/llvm/llvm-project/issues/118162>
2934 // SAFETY: Only one of `c1` and `c2` can be set.
2935 // For c1 to be set we need to have overflowed, but if we did then
2936 // `a` is at most `MAX-1`, which means that `c2` cannot possibly
2937 // overflow because it's adding at most `1` (since it came from `bool`)
2938 (b, unsafe { intrinsics::disjoint_bitor(c1, c2) })
2939 }
2940
2941 /// Calculates `self` + `rhs` with a signed `rhs`.
2942 ///
2943 /// Returns a tuple of the addition along with a boolean indicating
2944 /// whether an arithmetic overflow would occur. If an overflow would
2945 /// have occurred then the wrapped value is returned.
2946 ///
2947 /// # Examples
2948 ///
2949 /// ```
2950 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_add_signed(2), (3, false));")]
2951 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_add_signed(-2), (", stringify!($SelfT), "::MAX, true));")]
2952 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).overflowing_add_signed(4), (1, true));")]
2953 /// ```
2954 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
2955 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
2956 #[must_use = "this returns the result of the operation, \
2957 without modifying the original"]
2958 #[inline]
2959 pub const fn overflowing_add_signed(self, rhs: $SignedT) -> (Self, bool) {
2960 let (res, overflowed) = self.overflowing_add(rhs as Self);
2961 (res, overflowed ^ (rhs < 0))
2962 }
2963
2964 /// Calculates `self` - `rhs`.
2965 ///
2966 /// Returns a tuple of the subtraction along with a boolean indicating
2967 /// whether an arithmetic overflow would occur. If an overflow would
2968 /// have occurred then the wrapped value is returned.
2969 ///
2970 /// # Examples
2971 ///
2972 /// ```
2973 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_sub(2), (3, false));")]
2974 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".overflowing_sub(1), (", stringify!($SelfT), "::MAX, true));")]
2975 /// ```
2976 #[stable(feature = "wrapping", since = "1.7.0")]
2977 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2978 #[must_use = "this returns the result of the operation, \
2979 without modifying the original"]
2980 #[inline(always)]
2981 pub const fn overflowing_sub(self, rhs: Self) -> (Self, bool) {
2982 let (a, b) = intrinsics::sub_with_overflow(self as $ActualT, rhs as $ActualT);
2983 (a as Self, b)
2984 }
2985
2986 /// Calculates `self` − `rhs` − `borrow` and returns a tuple
2987 /// containing the difference and the output borrow.
2988 ///
2989 /// Performs "ternary subtraction" by subtracting both an integer
2990 /// operand and a borrow-in bit from `self`, and returns an output
2991 /// integer and a borrow-out bit. This allows chaining together multiple
2992 /// subtractions to create a wider subtraction, and can be useful for
2993 /// bignum subtraction.
2994 ///
2995 /// # Examples
2996 ///
2997 /// ```
2998 #[doc = concat!("// 9 6 (a = 9 × 2^", stringify!($BITS), " + 6)")]
2999 #[doc = concat!("// - 5 7 (b = 5 × 2^", stringify!($BITS), " + 7)")]
3000 /// // ---------
3001 #[doc = concat!("// 3 MAX (diff = 3 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")]
3002 ///
3003 #[doc = concat!("let (a1, a0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (9, 6);")]
3004 #[doc = concat!("let (b1, b0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (5, 7);")]
3005 /// let borrow0 = false;
3006 ///
3007 /// let (diff0, borrow1) = a0.borrowing_sub(b0, borrow0);
3008 /// assert_eq!(borrow1, true);
3009 /// let (diff1, borrow2) = a1.borrowing_sub(b1, borrow1);
3010 /// assert_eq!(borrow2, false);
3011 ///
3012 #[doc = concat!("assert_eq!((diff1, diff0), (3, ", stringify!($SelfT), "::MAX));")]
3013 /// ```
3014 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3015 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3016 #[must_use = "this returns the result of the operation, \
3017 without modifying the original"]
3018 #[inline]
3019 pub const fn borrowing_sub(self, rhs: Self, borrow: bool) -> (Self, bool) {
3020 // note: longer-term this should be done via an intrinsic, but this has been shown
3021 // to generate optimal code for now, and LLVM doesn't have an equivalent intrinsic
3022 let (a, c1) = self.overflowing_sub(rhs);
3023 let (b, c2) = a.overflowing_sub(borrow as $SelfT);
3024 // SAFETY: Only one of `c1` and `c2` can be set.
3025 // For c1 to be set we need to have underflowed, but if we did then
3026 // `a` is nonzero, which means that `c2` cannot possibly
3027 // underflow because it's subtracting at most `1` (since it came from `bool`)
3028 (b, unsafe { intrinsics::disjoint_bitor(c1, c2) })
3029 }
3030
3031 /// Calculates `self` - `rhs` with a signed `rhs`
3032 ///
3033 /// Returns a tuple of the subtraction along with a boolean indicating
3034 /// whether an arithmetic overflow would occur. If an overflow would
3035 /// have occurred then the wrapped value is returned.
3036 ///
3037 /// # Examples
3038 ///
3039 /// ```
3040 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_signed(2), (", stringify!($SelfT), "::MAX, true));")]
3041 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_signed(-2), (3, false));")]
3042 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).overflowing_sub_signed(-4), (1, true));")]
3043 /// ```
3044 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
3045 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
3046 #[must_use = "this returns the result of the operation, \
3047 without modifying the original"]
3048 #[inline]
3049 pub const fn overflowing_sub_signed(self, rhs: $SignedT) -> (Self, bool) {
3050 let (res, overflow) = self.overflowing_sub(rhs as Self);
3051
3052 (res, overflow ^ (rhs < 0))
3053 }
3054
3055 /// Computes the absolute difference between `self` and `other`.
3056 ///
3057 /// # Examples
3058 ///
3059 /// ```
3060 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".abs_diff(80), 20", stringify!($SelfT), ");")]
3061 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".abs_diff(110), 10", stringify!($SelfT), ");")]
3062 /// ```
3063 #[stable(feature = "int_abs_diff", since = "1.60.0")]
3064 #[rustc_const_stable(feature = "int_abs_diff", since = "1.60.0")]
3065 #[must_use = "this returns the result of the operation, \
3066 without modifying the original"]
3067 #[inline]
3068 pub const fn abs_diff(self, other: Self) -> Self {
3069 if size_of::<Self>() == 1 {
3070 // Trick LLVM into generating the psadbw instruction when SSE2
3071 // is available and this function is autovectorized for u8's.
3072 (self as i32).wrapping_sub(other as i32).unsigned_abs() as Self
3073 } else {
3074 if self < other {
3075 other - self
3076 } else {
3077 self - other
3078 }
3079 }
3080 }
3081
3082 /// Calculates the multiplication of `self` and `rhs`.
3083 ///
3084 /// Returns a tuple of the multiplication along with a boolean
3085 /// indicating whether an arithmetic overflow would occur. If an
3086 /// overflow would have occurred then the wrapped value is returned.
3087 ///
3088 /// If you want the *value* of the overflow, rather than just *whether*
3089 /// an overflow occurred, see [`Self::carrying_mul`].
3090 ///
3091 /// # Examples
3092 ///
3093 /// Please note that this example is shared among integer types, which is why `u32` is used.
3094 ///
3095 /// ```
3096 /// assert_eq!(5u32.overflowing_mul(2), (10, false));
3097 /// assert_eq!(1_000_000_000u32.overflowing_mul(10), (1410065408, true));
3098 /// ```
3099 #[stable(feature = "wrapping", since = "1.7.0")]
3100 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3101 #[must_use = "this returns the result of the operation, \
3102 without modifying the original"]
3103 #[inline(always)]
3104 pub const fn overflowing_mul(self, rhs: Self) -> (Self, bool) {
3105 let (a, b) = intrinsics::mul_with_overflow(self as $ActualT, rhs as $ActualT);
3106 (a as Self, b)
3107 }
3108
3109 /// Calculates the complete double-width product `self * rhs`.
3110 ///
3111 /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
3112 /// of the result as two separate values, in that order. As such,
3113 /// `a.widening_mul(b).0` produces the same result as `a.wrapping_mul(b)`.
3114 ///
3115 /// If you also need to add a value and carry to the wide result, then you want
3116 /// [`Self::carrying_mul_add`] instead.
3117 ///
3118 /// If you also need to add a carry to the wide result, then you want
3119 /// [`Self::carrying_mul`] instead.
3120 ///
3121 /// If you just want to know *whether* the multiplication overflowed, then you
3122 /// want [`Self::overflowing_mul`] instead.
3123 ///
3124 /// # Examples
3125 ///
3126 /// ```
3127 /// #![feature(widening_mul)]
3128 #[doc = concat!("assert_eq!(5_", stringify!($SelfT), ".widening_mul(7), (35, 0));")]
3129 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.widening_mul(", stringify!($SelfT), "::MAX), (1, ", stringify!($SelfT), "::MAX - 1));")]
3130 /// ```
3131 ///
3132 /// Compared to other `*_mul` methods:
3133 /// ```
3134 /// #![feature(widening_mul)]
3135 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::widening_mul(1 << ", stringify!($BITS_MINUS_ONE), ", 6), (0, 3));")]
3136 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::overflowing_mul(1 << ", stringify!($BITS_MINUS_ONE), ", 6), (0, true));")]
3137 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::wrapping_mul(1 << ", stringify!($BITS_MINUS_ONE), ", 6), 0);")]
3138 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::checked_mul(1 << ", stringify!($BITS_MINUS_ONE), ", 6), None);")]
3139 /// ```
3140 ///
3141 /// Please note that this example is shared among integer types, which is why `u32` is used.
3142 ///
3143 /// ```
3144 /// #![feature(widening_mul)]
3145 /// assert_eq!(5u32.widening_mul(2), (10, 0));
3146 /// assert_eq!(1_000_000_000u32.widening_mul(10), (1410065408, 2));
3147 /// ```
3148 #[unstable(feature = "widening_mul", issue = "152016")]
3149 #[rustc_const_unstable(feature = "widening_mul", issue = "152016")]
3150 #[must_use = "this returns the result of the operation, \
3151 without modifying the original"]
3152 #[inline]
3153 pub const fn widening_mul(self, rhs: Self) -> (Self, Self) {
3154 Self::carrying_mul_add(self, rhs, 0, 0)
3155 }
3156
3157 /// Calculates the "full multiplication" `self * rhs + carry`
3158 /// without the possibility to overflow.
3159 ///
3160 /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
3161 /// of the result as two separate values, in that order.
3162 ///
3163 /// Performs "long multiplication" which takes in an extra amount to add, and may return an
3164 /// additional amount of overflow. This allows for chaining together multiple
3165 /// multiplications to create "big integers" which represent larger values.
3166 ///
3167 /// If you also need to add a value, then use [`Self::carrying_mul_add`].
3168 ///
3169 /// # Examples
3170 ///
3171 /// Please note that this example is shared among integer types, which is why `u32` is used.
3172 ///
3173 /// ```
3174 /// assert_eq!(5u32.carrying_mul(2, 0), (10, 0));
3175 /// assert_eq!(5u32.carrying_mul(2, 10), (20, 0));
3176 /// assert_eq!(1_000_000_000u32.carrying_mul(10, 0), (1410065408, 2));
3177 /// assert_eq!(1_000_000_000u32.carrying_mul(10, 10), (1410065418, 2));
3178 #[doc = concat!("assert_eq!(",
3179 stringify!($SelfT), "::MAX.carrying_mul(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
3180 "(0, ", stringify!($SelfT), "::MAX));"
3181 )]
3182 /// ```
3183 ///
3184 /// This is the core operation needed for scalar multiplication when
3185 /// implementing it for wider-than-native types.
3186 ///
3187 /// ```
3188 /// fn scalar_mul_eq(little_endian_digits: &mut Vec<u16>, multiplicand: u16) {
3189 /// let mut carry = 0;
3190 /// for d in little_endian_digits.iter_mut() {
3191 /// (*d, carry) = d.carrying_mul(multiplicand, carry);
3192 /// }
3193 /// if carry != 0 {
3194 /// little_endian_digits.push(carry);
3195 /// }
3196 /// }
3197 ///
3198 /// let mut v = vec![10, 20];
3199 /// scalar_mul_eq(&mut v, 3);
3200 /// assert_eq!(v, [30, 60]);
3201 ///
3202 /// assert_eq!(0x87654321_u64 * 0xFEED, 0x86D3D159E38D);
3203 /// let mut v = vec![0x4321, 0x8765];
3204 /// scalar_mul_eq(&mut v, 0xFEED);
3205 /// assert_eq!(v, [0xE38D, 0xD159, 0x86D3]);
3206 /// ```
3207 ///
3208 /// If `carry` is zero, this is similar to [`overflowing_mul`](Self::overflowing_mul),
3209 /// except that it gives the value of the overflow instead of just whether one happened:
3210 ///
3211 /// ```
3212 /// # #![allow(unused_features)]
3213 /// #![feature(const_unsigned_bigint_helpers)]
3214 /// let r = u8::carrying_mul(7, 13, 0);
3215 /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(7, 13));
3216 /// let r = u8::carrying_mul(13, 42, 0);
3217 /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(13, 42));
3218 /// ```
3219 ///
3220 /// The value of the first field in the returned tuple matches what you'd get
3221 /// by combining the [`wrapping_mul`](Self::wrapping_mul) and
3222 /// [`wrapping_add`](Self::wrapping_add) methods:
3223 ///
3224 /// ```
3225 /// # #![allow(unused_features)]
3226 /// #![feature(const_unsigned_bigint_helpers)]
3227 /// assert_eq!(
3228 /// 789_u16.carrying_mul(456, 123).0,
3229 /// 789_u16.wrapping_mul(456).wrapping_add(123),
3230 /// );
3231 /// ```
3232 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3233 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3234 #[must_use = "this returns the result of the operation, \
3235 without modifying the original"]
3236 #[inline]
3237 pub const fn carrying_mul(self, rhs: Self, carry: Self) -> (Self, Self) {
3238 Self::carrying_mul_add(self, rhs, carry, 0)
3239 }
3240
3241 /// Calculates the "full multiplication" `self * rhs + carry + add`.
3242 ///
3243 /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
3244 /// of the result as two separate values, in that order.
3245 ///
3246 /// This cannot overflow, as the double-width result has exactly enough
3247 /// space for the largest possible result. This is equivalent to how, in
3248 /// decimal, 9 × 9 + 9 + 9 = 81 + 18 = 99 = 9×10⁰ + 9×10¹ = 10² - 1.
3249 ///
3250 /// Performs "long multiplication" which takes in an extra amount to add, and may return an
3251 /// additional amount of overflow. This allows for chaining together multiple
3252 /// multiplications to create "big integers" which represent larger values.
3253 ///
3254 /// If you don't need the `add` part, then you can use [`Self::carrying_mul`] instead.
3255 ///
3256 /// # Examples
3257 ///
3258 /// Please note that this example is shared between integer types,
3259 /// which explains why `u32` is used here.
3260 ///
3261 /// ```
3262 /// assert_eq!(5u32.carrying_mul_add(2, 0, 0), (10, 0));
3263 /// assert_eq!(5u32.carrying_mul_add(2, 10, 10), (30, 0));
3264 /// assert_eq!(1_000_000_000u32.carrying_mul_add(10, 0, 0), (1410065408, 2));
3265 /// assert_eq!(1_000_000_000u32.carrying_mul_add(10, 10, 10), (1410065428, 2));
3266 #[doc = concat!("assert_eq!(",
3267 stringify!($SelfT), "::MAX.carrying_mul_add(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
3268 "(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX));"
3269 )]
3270 /// ```
3271 ///
3272 /// This is the core per-digit operation for "grade school" O(n²) multiplication.
3273 ///
3274 /// Please note that this example is shared between integer types,
3275 /// using `u8` for simplicity of the demonstration.
3276 ///
3277 /// ```
3278 /// fn quadratic_mul<const N: usize>(a: [u8; N], b: [u8; N]) -> [u8; N] {
3279 /// let mut out = [0; N];
3280 /// for j in 0..N {
3281 /// let mut carry = 0;
3282 /// for i in 0..(N - j) {
3283 /// (out[j + i], carry) = u8::carrying_mul_add(a[i], b[j], out[j + i], carry);
3284 /// }
3285 /// }
3286 /// out
3287 /// }
3288 ///
3289 /// // -1 * -1 == 1
3290 /// assert_eq!(quadratic_mul([0xFF; 3], [0xFF; 3]), [1, 0, 0]);
3291 ///
3292 /// assert_eq!(u32::wrapping_mul(0x9e3779b9, 0x7f4a7c15), 0xcffc982d);
3293 /// assert_eq!(
3294 /// quadratic_mul(u32::to_le_bytes(0x9e3779b9), u32::to_le_bytes(0x7f4a7c15)),
3295 /// u32::to_le_bytes(0xcffc982d)
3296 /// );
3297 /// ```
3298 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3299 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3300 #[must_use = "this returns the result of the operation, \
3301 without modifying the original"]
3302 #[inline]
3303 pub const fn carrying_mul_add(self, rhs: Self, carry: Self, add: Self) -> (Self, Self) {
3304 intrinsics::carrying_mul_add(self, rhs, carry, add)
3305 }
3306
3307 /// Calculates the divisor when `self` is divided by `rhs`.
3308 ///
3309 /// Returns a tuple of the divisor along with a boolean indicating
3310 /// whether an arithmetic overflow would occur. Note that for unsigned
3311 /// integers overflow never occurs, so the second value is always
3312 /// `false`.
3313 ///
3314 /// # Panics
3315 ///
3316 /// This function will panic if `rhs` is zero.
3317 ///
3318 /// # Examples
3319 ///
3320 /// ```
3321 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_div(2), (2, false));")]
3322 /// ```
3323 #[inline(always)]
3324 #[stable(feature = "wrapping", since = "1.7.0")]
3325 #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
3326 #[must_use = "this returns the result of the operation, \
3327 without modifying the original"]
3328 #[track_caller]
3329 pub const fn overflowing_div(self, rhs: Self) -> (Self, bool) {
3330 (self / rhs, false)
3331 }
3332
3333 /// Calculates the quotient of Euclidean division `self.div_euclid(rhs)`.
3334 ///
3335 /// Returns a tuple of the divisor along with a boolean indicating
3336 /// whether an arithmetic overflow would occur. Note that for unsigned
3337 /// integers overflow never occurs, so the second value is always
3338 /// `false`.
3339 /// Since, for the positive integers, all common
3340 /// definitions of division are equal, this
3341 /// is exactly equal to `self.overflowing_div(rhs)`.
3342 ///
3343 /// # Panics
3344 ///
3345 /// This function will panic if `rhs` is zero.
3346 ///
3347 /// # Examples
3348 ///
3349 /// ```
3350 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_div_euclid(2), (2, false));")]
3351 /// ```
3352 #[inline(always)]
3353 #[stable(feature = "euclidean_division", since = "1.38.0")]
3354 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3355 #[must_use = "this returns the result of the operation, \
3356 without modifying the original"]
3357 #[track_caller]
3358 pub const fn overflowing_div_euclid(self, rhs: Self) -> (Self, bool) {
3359 (self / rhs, false)
3360 }
3361
3362 /// Calculates the remainder when `self` is divided by `rhs`.
3363 ///
3364 /// Returns a tuple of the remainder after dividing along with a boolean
3365 /// indicating whether an arithmetic overflow would occur. Note that for
3366 /// unsigned integers overflow never occurs, so the second value is
3367 /// always `false`.
3368 ///
3369 /// # Panics
3370 ///
3371 /// This function will panic if `rhs` is zero.
3372 ///
3373 /// # Examples
3374 ///
3375 /// ```
3376 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_rem(2), (1, false));")]
3377 /// ```
3378 #[inline(always)]
3379 #[stable(feature = "wrapping", since = "1.7.0")]
3380 #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
3381 #[must_use = "this returns the result of the operation, \
3382 without modifying the original"]
3383 #[track_caller]
3384 pub const fn overflowing_rem(self, rhs: Self) -> (Self, bool) {
3385 (self % rhs, false)
3386 }
3387
3388 /// Calculates the remainder `self.rem_euclid(rhs)` as if by Euclidean division.
3389 ///
3390 /// Returns a tuple of the modulo after dividing along with a boolean
3391 /// indicating whether an arithmetic overflow would occur. Note that for
3392 /// unsigned integers overflow never occurs, so the second value is
3393 /// always `false`.
3394 /// Since, for the positive integers, all common
3395 /// definitions of division are equal, this operation
3396 /// is exactly equal to `self.overflowing_rem(rhs)`.
3397 ///
3398 /// # Panics
3399 ///
3400 /// This function will panic if `rhs` is zero.
3401 ///
3402 /// # Examples
3403 ///
3404 /// ```
3405 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_rem_euclid(2), (1, false));")]
3406 /// ```
3407 #[inline(always)]
3408 #[stable(feature = "euclidean_division", since = "1.38.0")]
3409 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3410 #[must_use = "this returns the result of the operation, \
3411 without modifying the original"]
3412 #[track_caller]
3413 pub const fn overflowing_rem_euclid(self, rhs: Self) -> (Self, bool) {
3414 (self % rhs, false)
3415 }
3416
3417 /// Negates self in an overflowing fashion.
3418 ///
3419 /// Returns `!self + 1` using wrapping operations to return the value
3420 /// that represents the negation of this unsigned value. Note that for
3421 /// positive unsigned values overflow always occurs, but negating 0 does
3422 /// not overflow.
3423 ///
3424 /// # Examples
3425 ///
3426 /// ```
3427 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".overflowing_neg(), (0, false));")]
3428 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".overflowing_neg(), (-2i32 as ", stringify!($SelfT), ", true));")]
3429 /// ```
3430 #[inline(always)]
3431 #[stable(feature = "wrapping", since = "1.7.0")]
3432 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3433 #[must_use = "this returns the result of the operation, \
3434 without modifying the original"]
3435 pub const fn overflowing_neg(self) -> (Self, bool) {
3436 ((!self).wrapping_add(1), self != 0)
3437 }
3438
3439 /// Shifts self left by `rhs` bits.
3440 ///
3441 /// Returns a tuple of the shifted version of self along with a boolean
3442 /// indicating whether the shift value was larger than or equal to the
3443 /// number of bits. If the shift value is too large, then value is
3444 /// masked (N-1) where N is the number of bits, and this value is then
3445 /// used to perform the shift.
3446 ///
3447 /// # Examples
3448 ///
3449 /// ```
3450 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".overflowing_shl(4), (0x10, false));")]
3451 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".overflowing_shl(132), (0x10, true));")]
3452 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shl(", stringify!($BITS_MINUS_ONE), "), (0, false));")]
3453 /// ```
3454 #[stable(feature = "wrapping", since = "1.7.0")]
3455 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3456 #[must_use = "this returns the result of the operation, \
3457 without modifying the original"]
3458 #[inline(always)]
3459 pub const fn overflowing_shl(self, rhs: u32) -> (Self, bool) {
3460 (self.wrapping_shl(rhs), rhs >= Self::BITS)
3461 }
3462
3463 /// Shifts self right by `rhs` bits.
3464 ///
3465 /// Returns a tuple of the shifted version of self along with a boolean
3466 /// indicating whether the shift value was larger than or equal to the
3467 /// number of bits. If the shift value is too large, then value is
3468 /// masked (N-1) where N is the number of bits, and this value is then
3469 /// used to perform the shift.
3470 ///
3471 /// # Examples
3472 ///
3473 /// ```
3474 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shr(4), (0x1, false));")]
3475 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shr(132), (0x1, true));")]
3476 /// ```
3477 #[stable(feature = "wrapping", since = "1.7.0")]
3478 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3479 #[must_use = "this returns the result of the operation, \
3480 without modifying the original"]
3481 #[inline(always)]
3482 pub const fn overflowing_shr(self, rhs: u32) -> (Self, bool) {
3483 (self.wrapping_shr(rhs), rhs >= Self::BITS)
3484 }
3485
3486 /// Raises self to the power of `exp`, using exponentiation by squaring.
3487 ///
3488 /// Returns a tuple of the exponentiation along with a bool indicating
3489 /// whether an overflow happened.
3490 ///
3491 /// # Examples
3492 ///
3493 /// ```
3494 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".overflowing_pow(5), (243, false));")]
3495 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".overflowing_pow(0), (1, false));")]
3496 /// assert_eq!(3u8.overflowing_pow(6), (217, true));
3497 /// ```
3498 #[stable(feature = "no_panic_pow", since = "1.34.0")]
3499 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3500 #[must_use = "this returns the result of the operation, \
3501 without modifying the original"]
3502 #[inline]
3503 pub const fn overflowing_pow(self, mut exp: u32) -> (Self, bool) {
3504 if exp == 0{
3505 return (1,false);
3506 }
3507 let mut base = self;
3508 let mut acc: Self = 1;
3509 let mut overflown = false;
3510 // Scratch space for storing results of overflowing_mul.
3511 let mut r;
3512
3513 loop {
3514 if (exp & 1) == 1 {
3515 r = acc.overflowing_mul(base);
3516 // since exp!=0, finally the exp must be 1.
3517 if exp == 1 {
3518 r.1 |= overflown;
3519 return r;
3520 }
3521 acc = r.0;
3522 overflown |= r.1;
3523 }
3524 exp /= 2;
3525 r = base.overflowing_mul(base);
3526 base = r.0;
3527 overflown |= r.1;
3528 }
3529 }
3530
3531 /// Raises self to the power of `exp`, using exponentiation by squaring.
3532 ///
3533 /// # Examples
3534 ///
3535 /// ```
3536 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".pow(5), 32);")]
3537 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".pow(0), 1);")]
3538 /// ```
3539 #[stable(feature = "rust1", since = "1.0.0")]
3540 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3541 #[must_use = "this returns the result of the operation, \
3542 without modifying the original"]
3543 #[inline]
3544 #[rustc_inherit_overflow_checks]
3545 pub const fn pow(self, mut exp: u32) -> Self {
3546 if exp == 0 {
3547 return 1;
3548 }
3549 let mut base = self;
3550 let mut acc = 1;
3551
3552 if intrinsics::is_val_statically_known(exp) {
3553 while exp > 1 {
3554 if (exp & 1) == 1 {
3555 acc = acc * base;
3556 }
3557 exp /= 2;
3558 base = base * base;
3559 }
3560
3561 // since exp!=0, finally the exp must be 1.
3562 // Deal with the final bit of the exponent separately, since
3563 // squaring the base afterwards is not necessary and may cause a
3564 // needless overflow.
3565 acc * base
3566 } else {
3567 // This is faster than the above when the exponent is not known
3568 // at compile time. We can't use the same code for the constant
3569 // exponent case because LLVM is currently unable to unroll
3570 // this loop.
3571 loop {
3572 if (exp & 1) == 1 {
3573 acc = acc * base;
3574 // since exp!=0, finally the exp must be 1.
3575 if exp == 1 {
3576 return acc;
3577 }
3578 }
3579 exp /= 2;
3580 base = base * base;
3581 }
3582 }
3583 }
3584
3585 /// Returns the square root of the number, rounded down.
3586 ///
3587 /// # Examples
3588 ///
3589 /// ```
3590 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".isqrt(), 3);")]
3591 /// ```
3592 #[stable(feature = "isqrt", since = "1.84.0")]
3593 #[rustc_const_stable(feature = "isqrt", since = "1.84.0")]
3594 #[must_use = "this returns the result of the operation, \
3595 without modifying the original"]
3596 #[inline]
3597 pub const fn isqrt(self) -> Self {
3598 let result = imp::int_sqrt::$ActualT(self as $ActualT) as $SelfT;
3599
3600 // Inform the optimizer what the range of outputs is. If testing
3601 // `core` crashes with no panic message and a `num::int_sqrt::u*`
3602 // test failed, it's because your edits caused these assertions or
3603 // the assertions in `fn isqrt` of `nonzero.rs` to become false.
3604 //
3605 // SAFETY: Integer square root is a monotonically nondecreasing
3606 // function, which means that increasing the input will never
3607 // cause the output to decrease. Thus, since the input for unsigned
3608 // integers is bounded by `[0, <$ActualT>::MAX]`, sqrt(n) will be
3609 // bounded by `[sqrt(0), sqrt(<$ActualT>::MAX)]`.
3610 unsafe {
3611 const MAX_RESULT: $SelfT = imp::int_sqrt::$ActualT(<$ActualT>::MAX) as $SelfT;
3612 crate::hint::assert_unchecked(result <= MAX_RESULT);
3613 }
3614
3615 result
3616 }
3617
3618 /// Performs Euclidean division.
3619 ///
3620 /// Since, for the positive integers, all common
3621 /// definitions of division are equal, this
3622 /// is exactly equal to `self / rhs`.
3623 ///
3624 /// # Panics
3625 ///
3626 /// This function will panic if `rhs` is zero.
3627 ///
3628 /// # Examples
3629 ///
3630 /// ```
3631 #[doc = concat!("assert_eq!(7", stringify!($SelfT), ".div_euclid(4), 1); // or any other integer type")]
3632 /// ```
3633 #[stable(feature = "euclidean_division", since = "1.38.0")]
3634 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3635 #[must_use = "this returns the result of the operation, \
3636 without modifying the original"]
3637 #[inline(always)]
3638 #[track_caller]
3639 pub const fn div_euclid(self, rhs: Self) -> Self {
3640 self / rhs
3641 }
3642
3643
3644 /// Calculates the least remainder of `self` when divided by
3645 /// `rhs`.
3646 ///
3647 /// Since, for the positive integers, all common
3648 /// definitions of division are equal, this
3649 /// is exactly equal to `self % rhs`.
3650 ///
3651 /// # Panics
3652 ///
3653 /// This function will panic if `rhs` is zero.
3654 ///
3655 /// # Examples
3656 ///
3657 /// ```
3658 #[doc = concat!("assert_eq!(7", stringify!($SelfT), ".rem_euclid(4), 3); // or any other integer type")]
3659 /// ```
3660 #[doc(alias = "modulo", alias = "mod")]
3661 #[stable(feature = "euclidean_division", since = "1.38.0")]
3662 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3663 #[must_use = "this returns the result of the operation, \
3664 without modifying the original"]
3665 #[inline(always)]
3666 #[track_caller]
3667 pub const fn rem_euclid(self, rhs: Self) -> Self {
3668 self % rhs
3669 }
3670
3671 /// Calculates the quotient of `self` and `rhs`, rounding the result towards negative infinity.
3672 ///
3673 /// This is the same as performing `self / rhs` for all unsigned integers.
3674 ///
3675 /// # Panics
3676 ///
3677 /// This function will panic if `rhs` is zero.
3678 ///
3679 /// # Examples
3680 ///
3681 /// ```
3682 /// #![feature(int_roundings)]
3683 #[doc = concat!("assert_eq!(7_", stringify!($SelfT), ".div_floor(4), 1);")]
3684 /// ```
3685 #[unstable(feature = "int_roundings", issue = "88581")]
3686 #[must_use = "this returns the result of the operation, \
3687 without modifying the original"]
3688 #[inline(always)]
3689 #[track_caller]
3690 pub const fn div_floor(self, rhs: Self) -> Self {
3691 self / rhs
3692 }
3693
3694 /// Calculates the quotient of `self` and `rhs`, rounding the result towards positive infinity.
3695 ///
3696 /// # Panics
3697 ///
3698 /// This function will panic if `rhs` is zero.
3699 ///
3700 /// # Examples
3701 ///
3702 /// ```
3703 #[doc = concat!("assert_eq!(7_", stringify!($SelfT), ".div_ceil(4), 2);")]
3704 /// ```
3705 #[stable(feature = "int_roundings1", since = "1.73.0")]
3706 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3707 #[must_use = "this returns the result of the operation, \
3708 without modifying the original"]
3709 #[inline]
3710 #[track_caller]
3711 pub const fn div_ceil(self, rhs: Self) -> Self {
3712 let d = self / rhs;
3713 let r = self % rhs;
3714 if r > 0 {
3715 d + 1
3716 } else {
3717 d
3718 }
3719 }
3720
3721 /// Calculates the smallest value greater than or equal to `self` that
3722 /// is a multiple of `rhs`.
3723 ///
3724 /// # Panics
3725 ///
3726 /// This function will panic if `rhs` is zero.
3727 ///
3728 /// ## Overflow behavior
3729 ///
3730 /// On overflow, this function will panic if overflow checks are enabled (default in debug
3731 /// mode) and wrap if overflow checks are disabled (default in release mode).
3732 ///
3733 /// # Examples
3734 ///
3735 /// ```
3736 #[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".next_multiple_of(8), 16);")]
3737 #[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".next_multiple_of(8), 24);")]
3738 /// ```
3739 #[stable(feature = "int_roundings1", since = "1.73.0")]
3740 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3741 #[must_use = "this returns the result of the operation, \
3742 without modifying the original"]
3743 #[inline]
3744 #[rustc_inherit_overflow_checks]
3745 pub const fn next_multiple_of(self, rhs: Self) -> Self {
3746 match self % rhs {
3747 0 => self,
3748 r => self + (rhs - r)
3749 }
3750 }
3751
3752 /// Calculates the smallest value greater than or equal to `self` that
3753 /// is a multiple of `rhs`. Returns `None` if `rhs` is zero or the
3754 /// operation would result in overflow.
3755 ///
3756 /// # Examples
3757 ///
3758 /// ```
3759 #[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".checked_next_multiple_of(8), Some(16));")]
3760 #[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".checked_next_multiple_of(8), Some(24));")]
3761 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".checked_next_multiple_of(0), None);")]
3762 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_next_multiple_of(2), None);")]
3763 /// ```
3764 #[stable(feature = "int_roundings1", since = "1.73.0")]
3765 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3766 #[must_use = "this returns the result of the operation, \
3767 without modifying the original"]
3768 #[inline]
3769 pub const fn checked_next_multiple_of(self, rhs: Self) -> Option<Self> {
3770 match try_opt!(self.checked_rem(rhs)) {
3771 0 => Some(self),
3772 // rhs - r cannot overflow because r is smaller than rhs
3773 r => self.checked_add(rhs - r)
3774 }
3775 }
3776
3777 /// Returns `true` if `self` is an integer multiple of `rhs`, and false otherwise.
3778 ///
3779 /// This function is equivalent to `self % rhs == 0`, except that it will not panic
3780 /// for `rhs == 0`. Instead, `0.is_multiple_of(0) == true`, and for any non-zero `n`,
3781 /// `n.is_multiple_of(0) == false`.
3782 ///
3783 /// # Examples
3784 ///
3785 /// ```
3786 #[doc = concat!("assert!(6_", stringify!($SelfT), ".is_multiple_of(2));")]
3787 #[doc = concat!("assert!(!5_", stringify!($SelfT), ".is_multiple_of(2));")]
3788 ///
3789 #[doc = concat!("assert!(0_", stringify!($SelfT), ".is_multiple_of(0));")]
3790 #[doc = concat!("assert!(!6_", stringify!($SelfT), ".is_multiple_of(0));")]
3791 /// ```
3792 #[stable(feature = "unsigned_is_multiple_of", since = "1.87.0")]
3793 #[rustc_const_stable(feature = "unsigned_is_multiple_of", since = "1.87.0")]
3794 #[must_use]
3795 #[inline]
3796 pub const fn is_multiple_of(self, rhs: Self) -> bool {
3797 match rhs {
3798 0 => self == 0,
3799 _ => self % rhs == 0,
3800 }
3801 }
3802
3803 /// Returns `true` if and only if `self == 2^k` for some unsigned integer `k`.
3804 ///
3805 /// # Examples
3806 ///
3807 /// ```
3808 #[doc = concat!("assert!(16", stringify!($SelfT), ".is_power_of_two());")]
3809 #[doc = concat!("assert!(!10", stringify!($SelfT), ".is_power_of_two());")]
3810 /// ```
3811 #[must_use]
3812 #[stable(feature = "rust1", since = "1.0.0")]
3813 #[rustc_const_stable(feature = "const_is_power_of_two", since = "1.32.0")]
3814 #[inline(always)]
3815 pub const fn is_power_of_two(self) -> bool {
3816 self.count_ones() == 1
3817 }
3818
3819 // Returns one less than next power of two.
3820 // (For 8u8 next power of two is 8u8 and for 6u8 it is 8u8)
3821 //
3822 // 8u8.one_less_than_next_power_of_two() == 7
3823 // 6u8.one_less_than_next_power_of_two() == 7
3824 //
3825 // This method cannot overflow, as in the `next_power_of_two`
3826 // overflow cases it instead ends up returning the maximum value
3827 // of the type, and can return 0 for 0.
3828 #[inline]
3829 const fn one_less_than_next_power_of_two(self) -> Self {
3830 if self <= 1 { return 0; }
3831
3832 let p = self - 1;
3833 // SAFETY: Because `p > 0`, it cannot consist entirely of leading zeros.
3834 // That means the shift is always in-bounds, and some processors
3835 // (such as intel pre-haswell) have more efficient ctlz
3836 // intrinsics when the argument is non-zero.
3837 let z = unsafe { intrinsics::ctlz_nonzero(p) };
3838 <$SelfT>::MAX >> z
3839 }
3840
3841 /// Returns the smallest power of two greater than or equal to `self`.
3842 ///
3843 /// When return value overflows (i.e., `self > (1 << (N-1))` for type
3844 /// `uN`), it panics in debug mode and the return value is wrapped to 0 in
3845 /// release mode (the only situation in which this method can return 0).
3846 ///
3847 /// # Examples
3848 ///
3849 /// ```
3850 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".next_power_of_two(), 2);")]
3851 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".next_power_of_two(), 4);")]
3852 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".next_power_of_two(), 1);")]
3853 /// ```
3854 #[stable(feature = "rust1", since = "1.0.0")]
3855 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3856 #[must_use = "this returns the result of the operation, \
3857 without modifying the original"]
3858 #[inline]
3859 #[rustc_inherit_overflow_checks]
3860 pub const fn next_power_of_two(self) -> Self {
3861 self.one_less_than_next_power_of_two() + 1
3862 }
3863
3864 /// Returns the smallest power of two greater than or equal to `self`. If
3865 /// the next power of two is greater than the type's maximum value,
3866 /// `None` is returned, otherwise the power of two is wrapped in `Some`.
3867 ///
3868 /// # Examples
3869 ///
3870 /// ```
3871 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_next_power_of_two(), Some(2));")]
3872 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".checked_next_power_of_two(), Some(4));")]
3873 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_next_power_of_two(), None);")]
3874 /// ```
3875 #[inline]
3876 #[stable(feature = "rust1", since = "1.0.0")]
3877 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3878 #[must_use = "this returns the result of the operation, \
3879 without modifying the original"]
3880 pub const fn checked_next_power_of_two(self) -> Option<Self> {
3881 self.one_less_than_next_power_of_two().checked_add(1)
3882 }
3883
3884 /// Returns the smallest power of two greater than or equal to `n`. If
3885 /// the next power of two is greater than the type's maximum value,
3886 /// the return value is wrapped to `0`.
3887 ///
3888 /// # Examples
3889 ///
3890 /// ```
3891 /// #![feature(wrapping_next_power_of_two)]
3892 ///
3893 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".wrapping_next_power_of_two(), 2);")]
3894 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".wrapping_next_power_of_two(), 4);")]
3895 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_next_power_of_two(), 0);")]
3896 /// ```
3897 #[inline]
3898 #[unstable(feature = "wrapping_next_power_of_two", issue = "32463",
3899 reason = "needs decision on wrapping behavior")]
3900 #[must_use = "this returns the result of the operation, \
3901 without modifying the original"]
3902 pub const fn wrapping_next_power_of_two(self) -> Self {
3903 self.one_less_than_next_power_of_two().wrapping_add(1)
3904 }
3905
3906 /// Returns the memory representation of this integer as a byte array in
3907 /// big-endian (network) byte order.
3908 ///
3909 #[doc = $to_xe_bytes_doc]
3910 ///
3911 /// # Examples
3912 ///
3913 /// ```
3914 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_be_bytes();")]
3915 #[doc = concat!("assert_eq!(bytes, ", $be_bytes, ");")]
3916 /// ```
3917 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
3918 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
3919 #[must_use = "this returns the result of the operation, \
3920 without modifying the original"]
3921 #[inline]
3922 pub const fn to_be_bytes(self) -> [u8; size_of::<Self>()] {
3923 self.to_be().to_ne_bytes()
3924 }
3925
3926 /// Returns the memory representation of this integer as a byte array in
3927 /// little-endian byte order.
3928 ///
3929 #[doc = $to_xe_bytes_doc]
3930 ///
3931 /// # Examples
3932 ///
3933 /// ```
3934 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_le_bytes();")]
3935 #[doc = concat!("assert_eq!(bytes, ", $le_bytes, ");")]
3936 /// ```
3937 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
3938 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
3939 #[must_use = "this returns the result of the operation, \
3940 without modifying the original"]
3941 #[inline]
3942 pub const fn to_le_bytes(self) -> [u8; size_of::<Self>()] {
3943 self.to_le().to_ne_bytes()
3944 }
3945
3946 /// Returns the memory representation of this integer as a byte array in
3947 /// native byte order.
3948 ///
3949 /// As the target platform's native endianness is used, portable code
3950 /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate,
3951 /// instead.
3952 ///
3953 #[doc = $to_xe_bytes_doc]
3954 ///
3955 /// [`to_be_bytes`]: Self::to_be_bytes
3956 /// [`to_le_bytes`]: Self::to_le_bytes
3957 ///
3958 /// # Examples
3959 ///
3960 /// ```
3961 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_ne_bytes();")]
3962 /// assert_eq!(
3963 /// bytes,
3964 /// if cfg!(target_endian = "big") {
3965 #[doc = concat!(" ", $be_bytes)]
3966 /// } else {
3967 #[doc = concat!(" ", $le_bytes)]
3968 /// }
3969 /// );
3970 /// ```
3971 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
3972 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
3973 #[must_use = "this returns the result of the operation, \
3974 without modifying the original"]
3975 #[allow(unnecessary_transmutes)]
3976 // SAFETY: const sound because integers are plain old datatypes so we can always
3977 // transmute them to arrays of bytes
3978 #[inline]
3979 pub const fn to_ne_bytes(self) -> [u8; size_of::<Self>()] {
3980 // SAFETY: integers are plain old datatypes so we can always transmute them to
3981 // arrays of bytes
3982 unsafe { mem::transmute(self) }
3983 }
3984
3985 /// Creates a native endian integer value from its representation
3986 /// as a byte array in big endian.
3987 ///
3988 #[doc = $from_xe_bytes_doc]
3989 ///
3990 /// # Examples
3991 ///
3992 /// ```
3993 #[doc = concat!("let value = ", stringify!($SelfT), "::from_be_bytes(", $be_bytes, ");")]
3994 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
3995 /// ```
3996 ///
3997 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
3998 ///
3999 /// ```
4000 #[doc = concat!("fn read_be_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4001 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4002 /// *input = rest;
4003 #[doc = concat!(" ", stringify!($SelfT), "::from_be_bytes(int_bytes.try_into().unwrap())")]
4004 /// }
4005 /// ```
4006 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4007 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4008 #[must_use]
4009 #[inline]
4010 pub const fn from_be_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4011 Self::from_be(Self::from_ne_bytes(bytes))
4012 }
4013
4014 /// Creates a native endian integer value from its representation
4015 /// as a byte array in little endian.
4016 ///
4017 #[doc = $from_xe_bytes_doc]
4018 ///
4019 /// # Examples
4020 ///
4021 /// ```
4022 #[doc = concat!("let value = ", stringify!($SelfT), "::from_le_bytes(", $le_bytes, ");")]
4023 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4024 /// ```
4025 ///
4026 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4027 ///
4028 /// ```
4029 #[doc = concat!("fn read_le_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4030 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4031 /// *input = rest;
4032 #[doc = concat!(" ", stringify!($SelfT), "::from_le_bytes(int_bytes.try_into().unwrap())")]
4033 /// }
4034 /// ```
4035 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4036 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4037 #[must_use]
4038 #[inline]
4039 pub const fn from_le_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4040 Self::from_le(Self::from_ne_bytes(bytes))
4041 }
4042
4043 /// Creates a native endian integer value from its memory representation
4044 /// as a byte array in native endianness.
4045 ///
4046 /// As the target platform's native endianness is used, portable code
4047 /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
4048 /// appropriate instead.
4049 ///
4050 /// [`from_be_bytes`]: Self::from_be_bytes
4051 /// [`from_le_bytes`]: Self::from_le_bytes
4052 ///
4053 #[doc = $from_xe_bytes_doc]
4054 ///
4055 /// # Examples
4056 ///
4057 /// ```
4058 #[doc = concat!("let value = ", stringify!($SelfT), "::from_ne_bytes(if cfg!(target_endian = \"big\") {")]
4059 #[doc = concat!(" ", $be_bytes, "")]
4060 /// } else {
4061 #[doc = concat!(" ", $le_bytes, "")]
4062 /// });
4063 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4064 /// ```
4065 ///
4066 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4067 ///
4068 /// ```
4069 #[doc = concat!("fn read_ne_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4070 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4071 /// *input = rest;
4072 #[doc = concat!(" ", stringify!($SelfT), "::from_ne_bytes(int_bytes.try_into().unwrap())")]
4073 /// }
4074 /// ```
4075 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4076 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4077 #[allow(unnecessary_transmutes)]
4078 #[must_use]
4079 // SAFETY: const sound because integers are plain old datatypes so we can always
4080 // transmute to them
4081 #[inline]
4082 pub const fn from_ne_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4083 // SAFETY: integers are plain old datatypes so we can always transmute to them
4084 unsafe { mem::transmute(bytes) }
4085 }
4086
4087 /// New code should prefer to use
4088 #[doc = concat!("[`", stringify!($SelfT), "::MIN", "`] instead.")]
4089 ///
4090 /// Returns the smallest value that can be represented by this integer type.
4091 #[stable(feature = "rust1", since = "1.0.0")]
4092 #[rustc_promotable]
4093 #[inline(always)]
4094 #[rustc_const_stable(feature = "const_max_value", since = "1.32.0")]
4095 #[deprecated(since = "TBD", note = "replaced by the `MIN` associated constant on this type")]
4096 #[rustc_diagnostic_item = concat!(stringify!($SelfT), "_legacy_fn_min_value")]
4097 pub const fn min_value() -> Self { Self::MIN }
4098
4099 /// New code should prefer to use
4100 #[doc = concat!("[`", stringify!($SelfT), "::MAX", "`] instead.")]
4101 ///
4102 /// Returns the largest value that can be represented by this integer type.
4103 #[stable(feature = "rust1", since = "1.0.0")]
4104 #[rustc_promotable]
4105 #[inline(always)]
4106 #[rustc_const_stable(feature = "const_max_value", since = "1.32.0")]
4107 #[deprecated(since = "TBD", note = "replaced by the `MAX` associated constant on this type")]
4108 #[rustc_diagnostic_item = concat!(stringify!($SelfT), "_legacy_fn_max_value")]
4109 pub const fn max_value() -> Self { Self::MAX }
4110 }
4111}