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use crate::block_device::{BlockDevice, BLOCK_SIZE};
use std::sync::Arc;
pub struct Bitmap {
pub starting_block: usize,
pub length: usize,
pub device: Arc<dyn BlockDevice>,
pub data: Vec<u8>,
}
impl Bitmap {
pub(crate) fn new(starting_block: usize, length: usize, device: Arc<dyn BlockDevice>) -> Self {
Self {
starting_block,
length,
device,
data: vec![0u8; length * BLOCK_SIZE],
}
}
pub(crate) fn allocate(&mut self) -> Option<usize> {
for (i, byte) in self.data.iter_mut().enumerate() {
let leading_ones = byte.leading_ones();
if leading_ones != 8 {
*byte |= (1 << (7 - leading_ones)) as u8;
return Some(i * 8 + leading_ones as usize);
}
}
None
}
pub(crate) fn query(&self, index: usize) -> bool {
if index == 0 {
false
} else {
self.data[index / 8] & ((1 << (7 - index % 8)) as u8) != 0
}
}
pub(crate) fn deallocate(&mut self, index: usize) -> bool {
if self.query(index) {
let mask = !(1u8 << (7 - index % 8));
self.data[index / 8] &= mask;
true
} else {
false
}
}
}
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