Struct Bitmap

#[repr(align(8))]
pub struct Bitmap { /* private fields */ }

Represents a C bitmap. Wraps underlying C bitmap API.

Invariants

Must reference a [c_ulong] long enough to fit data.len() bits.

Implementations

impl Bitmap

pub unsafe fn from_raw<'a>(ptr: *const usize, nbits: usize) -> &'a Bitmap

Borrows a C bitmap.

Safety

• ptr holds a non-null address of an initialized array of unsigned long that is large enough to hold nbits bits.
• the array must not be freed for the lifetime of this Bitmap
• concurrent access only happens through atomic operations

pub unsafe fn from_raw_mut<'a>(ptr: *mut usize, nbits: usize) -> &'a mut Bitmap

Borrows a C bitmap exclusively.

Safety

• ptr holds a non-null address of an initialized array of unsigned long that is large enough to hold nbits bits.
• the array must not be freed for the lifetime of this Bitmap
• no concurrent access may happen.

pub fn as_ptr(&self) -> *const usize

Returns a raw pointer to the backing Bitmap.

pub fn as_mut_ptr(&mut self) -> *mut usize

Returns a mutable raw pointer to the backing Bitmap.

pub fn len(&self) -> usize

Returns length of this Bitmap.

impl Bitmap

pub fn set_bit(&mut self, index: usize)

Set bit with index index.

ATTENTION: set_bit is non-atomic, which differs from the naming convention in C code. The corresponding C function is __set_bit.

If CONFIG_RUST_BITMAP_HARDENED is not enabled and index is greater than or equal to self.nbits, does nothing.

Panics

Panics if CONFIG_RUST_BITMAP_HARDENED is enabled and index is greater than or equal to self.nbits.

pub fn set_bit_atomic(&self, index: usize)

Set bit with index index, atomically.

This is a relaxed atomic operation (no implied memory barriers).

ATTENTION: The naming convention differs from C, where the corresponding function is called set_bit.

If CONFIG_RUST_BITMAP_HARDENED is not enabled and index is greater than or equal to self.len(), does nothing.

Panics

Panics if CONFIG_RUST_BITMAP_HARDENED is enabled and index is greater than or equal to self.len().

pub fn clear_bit(&mut self, index: usize)

Clear index bit.

ATTENTION: clear_bit is non-atomic, which differs from the naming convention in C code. The corresponding C function is __clear_bit.

If CONFIG_RUST_BITMAP_HARDENED is not enabled and index is greater than or equal to self.len(), does nothing.

Panics

Panics if CONFIG_RUST_BITMAP_HARDENED is enabled and index is greater than or equal to self.len().

pub fn clear_bit_atomic(&self, index: usize)

Clear index bit, atomically.

This is a relaxed atomic operation (no implied memory barriers).

ATTENTION: The naming convention differs from C, where the corresponding function is called clear_bit.

If CONFIG_RUST_BITMAP_HARDENED is not enabled and index is greater than or equal to self.len(), does nothing.

Panics

Panics if CONFIG_RUST_BITMAP_HARDENED is enabled and index is greater than or equal to self.len().

pub fn copy_and_extend(&mut self, src: &Bitmap)

Copy src into this Bitmap and set any remaining bits to zero.

Examples

use kernel::alloc::{AllocError, flags::GFP_KERNEL};
use kernel::bitmap::BitmapVec;

let mut long_bitmap = BitmapVec::new(256, GFP_KERNEL)?;

assert_eq!(None, long_bitmap.last_bit());

let mut short_bitmap = BitmapVec::new(16, GFP_KERNEL)?;

short_bitmap.set_bit(7);
long_bitmap.copy_and_extend(&short_bitmap);
assert_eq!(Some(7), long_bitmap.last_bit());

pub fn last_bit(&self) -> Option<usize>

Finds last set bit.

Examples

use kernel::alloc::{AllocError, flags::GFP_KERNEL};
use kernel::bitmap::BitmapVec;

let bitmap = BitmapVec::new(64, GFP_KERNEL)?;

match bitmap.last_bit() {
    Some(idx) => {
        pr_info!("The last bit has index {idx}.\n");
    }
    None => {
        pr_info!("All bits in this bitmap are 0.\n");
    }
}

pub fn next_bit(&self, start: usize) -> Option<usize>

Finds next set bit, starting from start.

Returns None if start is greater or equal to self.nbits.

pub fn next_zero_bit(&self, start: usize) -> Option<usize>

Finds next zero bit, starting from start. Returns None if start is greater than or equal to self.len().