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use super::buffer::Buffer;
use crate::util::bit_util;
#[derive(PartialEq, Debug)]
pub struct Bitmap {
bits: Buffer,
}
impl Bitmap {
pub fn new(num_bits: usize) -> Self {
let num_bytes = num_bits / 8 + if num_bits % 8 > 0 { 1 } else { 0 };
let r = num_bytes % 64;
let len = if r == 0 {
num_bytes
} else {
num_bytes + 64 - r
};
let mut v = Vec::with_capacity(len);
for _ in 0..len {
v.push(255);
}
Bitmap {
bits: Buffer::from(&v[..]),
}
}
pub fn len(&self) -> usize {
self.bits.len()
}
pub fn is_set(&self, i: usize) -> bool {
assert!(i < (self.bits.len() << 3));
unsafe { bit_util::get_bit_raw(self.bits.raw_data(), i) }
}
}
impl From<Buffer> for Bitmap {
fn from(buf: Buffer) -> Self {
Self { bits: buf }
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_bitmap_length() {
assert_eq!(64, Bitmap::new(63 * 8).len());
assert_eq!(64, Bitmap::new(64 * 8).len());
assert_eq!(128, Bitmap::new(65 * 8).len());
}
#[test]
fn test_bitmap_is_set() {
let bitmap = Bitmap::from(Buffer::from([0b01001010]));
assert_eq!(false, bitmap.is_set(0));
assert_eq!(true, bitmap.is_set(1));
assert_eq!(false, bitmap.is_set(2));
assert_eq!(true, bitmap.is_set(3));
assert_eq!(false, bitmap.is_set(4));
assert_eq!(false, bitmap.is_set(5));
assert_eq!(true, bitmap.is_set(6));
assert_eq!(false, bitmap.is_set(7));
}
}