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Use usize as the Block instead of u32 #74

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merged 5 commits into from
Jan 9, 2023
Merged

Use usize as the Block instead of u32 #74

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8288a2e
Use usize as Block
james7132 Jun 24, 2022
64f9add
Speed up Ones
james7132 Jun 24, 2022
4e2cd04
Get rid of hard coded 32s
james7132 Jun 24, 2022
7a15c0d
Merge branch 'master' into usize
james7132 Jan 9, 2023
fff81ec
Fix tests
james7132 Jan 9, 2023
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6 changes: 3 additions & 3 deletions benches/benches.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
extern crate test;
extern crate fixedbitset;
use test::Bencher;
use fixedbitset::{FixedBitSet};
use fixedbitset::{FixedBitSet, Block};
use std::mem::size_of;

#[inline]
Expand All @@ -18,8 +18,8 @@ fn iter_ones_using_contains<F: FnMut(usize)>(fb: &FixedBitSet, f: &mut F) {
#[inline]
fn iter_ones_using_slice_directly<F: FnMut(usize)>(fb: &FixedBitSet, f: &mut F) {
for (block_idx, &block) in fb.as_slice().iter().enumerate() {
let mut bit_pos = block_idx * size_of::<u32>() * 8;
let mut block: u32 = block;
let mut bit_pos = block_idx * size_of::<Block>() * 8;
let mut block: Block = block;

while block != 0 {
if (block & 1) == 1 {
Expand Down
62 changes: 29 additions & 33 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -37,12 +37,12 @@ use std::cmp::{Ord, Ordering};
use std::iter::{Chain, FromIterator};
use std::ops::{BitAnd, BitAndAssign, BitOr, BitOrAssign, BitXor, BitXorAssign, Index};

const BITS: usize = 32;
type Block = u32;
const BITS: usize = std::mem::size_of::<Block>() * 8;
pub type Block = usize;

#[inline]
fn div_rem(x: usize, d: usize) -> (usize, usize) {
(x / d, x % d)
fn div_rem(x: usize) -> (usize, usize) {
(x / BITS, x % BITS)
}

/// `FixedBitSet` is a simple fixed size set of bits that each can
Expand Down Expand Up @@ -73,7 +73,7 @@ impl FixedBitSet {
/// Create a new **FixedBitSet** with a specific number of bits,
/// all initially clear.
pub fn with_capacity(bits: usize) -> Self {
let (mut blocks, rem) = div_rem(bits, BITS);
let (mut blocks, rem) = div_rem(bits);
blocks += (rem > 0) as usize;
FixedBitSet {
data: vec![0; blocks],
Expand All @@ -95,15 +95,15 @@ impl FixedBitSet {
/// assert_eq!(format!("{:b}", bs), "0010");
/// ```
pub fn with_capacity_and_blocks<I: IntoIterator<Item = Block>>(bits: usize, blocks: I) -> Self {
let (mut n_blocks, rem) = div_rem(bits, BITS);
let (mut n_blocks, rem) = div_rem(bits);
n_blocks += (rem > 0) as usize;
let mut data: Vec<Block> = blocks.into_iter().collect();
// Pad data with zeros if smaller or truncate if larger
if data.len() != n_blocks {
data.resize(n_blocks, 0);
}
// Disable bits in blocks beyond capacity
let end = data.len() * 32;
let end = data.len() * BITS;
for (block, mask) in Masks::new(bits..end, end) {
unsafe {
*data.get_unchecked_mut(block) &= !mask;
Expand All @@ -114,7 +114,7 @@ impl FixedBitSet {

/// Grow capacity to **bits**, all new bits initialized to zero
pub fn grow(&mut self, bits: usize) {
let (mut blocks, rem) = div_rem(bits, BITS);
let (mut blocks, rem) = div_rem(bits);
blocks += (rem > 0) as usize;
if bits > self.length {
self.length = bits;
Expand Down Expand Up @@ -185,7 +185,7 @@ impl FixedBitSet {
/// Note: Also available with index syntax: `bitset[bit]`.
#[inline]
pub fn contains(&self, bit: usize) -> bool {
let (block, i) = div_rem(bit, BITS);
let (block, i) = div_rem(bit);
match self.data.get(block) {
None => false,
Some(b) => (b & (1 << i)) != 0,
Expand All @@ -211,7 +211,7 @@ impl FixedBitSet {
bit,
self.length
);
let (block, i) = div_rem(bit, BITS);
let (block, i) = div_rem(bit);
unsafe {
*self.data.get_unchecked_mut(block) |= 1 << i;
}
Expand All @@ -228,7 +228,7 @@ impl FixedBitSet {
bit,
self.length
);
let (block, i) = div_rem(bit, BITS);
let (block, i) = div_rem(bit);
unsafe {
let word = self.data.get_unchecked_mut(block);
let prev = *word & (1 << i) != 0;
Expand All @@ -247,7 +247,7 @@ impl FixedBitSet {
bit,
self.length
);
let (block, i) = div_rem(bit, BITS);
let (block, i) = div_rem(bit);
unsafe {
*self.data.get_unchecked_mut(block) ^= 1 << i;
}
Expand All @@ -261,7 +261,7 @@ impl FixedBitSet {
bit,
self.length
);
let (block, i) = div_rem(bit, BITS);
let (block, i) = div_rem(bit);
unsafe {
let elt = self.data.get_unchecked_mut(block);
if enabled {
Expand All @@ -283,7 +283,7 @@ impl FixedBitSet {
to,
self.length
);
let (to_block, t) = div_rem(to, BITS);
let (to_block, t) = div_rem(to);
let enabled = self.contains(from);
unsafe {
let to_elt = self.data.get_unchecked_mut(to_block);
Expand Down Expand Up @@ -352,16 +352,16 @@ impl FixedBitSet {
}
}

/// View the bitset as a slice of `u32` blocks
/// View the bitset as a slice of `Block` blocks
#[inline]
pub fn as_slice(&self) -> &[u32] {
pub fn as_slice(&self) -> &[Block] {
&self.data
}

/// View the bitset as a mutable slice of `u32` blocks. Writing past the bitlength in the last
/// View the bitset as a mutable slice of `Block` blocks. Writing past the bitlength in the last
/// will cause `contains` to return potentially incorrect results for bits past the bitlength.
#[inline]
pub fn as_mut_slice(&mut self) -> &mut [u32] {
pub fn as_mut_slice(&mut self) -> &mut [Block] {
&mut self.data
}

Expand All @@ -374,12 +374,12 @@ impl FixedBitSet {
Some((&block, rem)) => Ones {
bitset: block,
block_idx: 0,
remaining_blocks: rem,
remaining_blocks: rem.iter(),
},
None => Ones {
bitset: 0,
block_idx: 0,
remaining_blocks: &[],
remaining_blocks: [].iter(),
},
}
}
Expand Down Expand Up @@ -615,8 +615,8 @@ impl Masks {
length
);

let (first_block, first_rem) = div_rem(start, BITS);
let (last_block, last_rem) = div_rem(end, BITS);
let (first_block, first_rem) = div_rem(start);
let (last_block, last_rem) = div_rem(end);

Masks {
first_block: first_block as usize,
Expand Down Expand Up @@ -660,7 +660,7 @@ impl Iterator for Masks {
pub struct Ones<'a> {
bitset: Block,
block_idx: usize,
remaining_blocks: &'a [Block],
remaining_blocks: std::slice::Iter<'a, Block>,
}

impl<'a> Iterator for Ones<'a> {
Expand All @@ -669,17 +669,13 @@ impl<'a> Iterator for Ones<'a> {
#[inline]
fn next(&mut self) -> Option<Self::Item> {
while self.bitset == 0 {
if self.remaining_blocks.is_empty() {
return None;
}
self.bitset = self.remaining_blocks[0];
self.remaining_blocks = &self.remaining_blocks[1..];
self.block_idx += 1;
self.bitset = *self.remaining_blocks.next()?;
self.block_idx += BITS;
}
let t = self.bitset & (0 as Block).wrapping_sub(self.bitset);
let r = self.bitset.trailing_zeros() as usize;
self.bitset ^= t;
Some(self.block_idx * BITS + r)
Some(self.block_idx + r)
}
}

Expand Down Expand Up @@ -860,7 +856,7 @@ mod tests {

#[test]
fn with_blocks() {
let fb = FixedBitSet::with_capacity_and_blocks(50, vec![8u32, 0u32]);
let fb = FixedBitSet::with_capacity_and_blocks(50, vec![8, 0]);
assert!(fb.contains(3));

let ones: Vec<_> = fb.ones().collect();
Expand All @@ -869,14 +865,14 @@ mod tests {

#[test]
fn with_blocks_too_small() {
let mut fb = FixedBitSet::with_capacity_and_blocks(500, vec![8u32, 0u32]);
let mut fb = FixedBitSet::with_capacity_and_blocks(500, vec![8, 0]);
fb.insert(400);
assert!(fb.contains(400));
}

#[test]
fn with_blocks_too_big() {
let fb = FixedBitSet::with_capacity_and_blocks(1, vec![8u32]);
let fb = FixedBitSet::with_capacity_and_blocks(1, vec![8]);

// since capacity is 1, 3 shouldn't be set here
assert!(!fb.contains(3));
Expand Down