37 lines
942 B
Rust
37 lines
942 B
Rust
#![allow(dead_code)]
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const SEG_SIZE: usize = usize::BITS as usize;
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#[derive(Default)]
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pub struct Bitfield {
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vals: Vec<usize>,
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}
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impl Bitfield {
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pub fn take(&mut self, val: u32) {
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let idx = val as usize / SEG_SIZE;
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let pos = val as usize % SEG_SIZE;
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while self.vals.len() <= idx {
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self.vals.push(!0);
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}
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self.vals[idx] &= !(1 << pos);
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}
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pub fn acquire(&mut self) -> u32 {
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for (idx, n) in self.vals.iter_mut().enumerate() {
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if *n != 0 {
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let pos = n.trailing_zeros();
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*n &= !(1 << pos);
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return (idx * SEG_SIZE) as u32 + pos;
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}
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}
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self.vals.push(!1);
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((self.vals.len() - 1) * SEG_SIZE) as u32
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}
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pub fn release(&mut self, val: u32) {
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let idx = val as usize / SEG_SIZE;
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let pos = val as usize % SEG_SIZE;
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self.vals[idx] |= 1 << pos;
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}
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}
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