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use crate::weak_slice::WeakSliceMut;
pub(crate) struct SymBuf<'a> {
buf: WeakSliceMut<'a, u8>,
filled: usize,
}
impl<'a> SymBuf<'a> {
#[inline]
pub fn iter(&self) -> impl Iterator<Item = (u16, u8)> + '_ {
self.buf.as_slice()[..self.filled]
.chunks_exact(3)
.map(|chunk| match *chunk {
[dist_low, dist_high, lc] => (u16::from_le_bytes([dist_low, dist_high]), lc),
_ => unreachable!("chunks are exactly 3 elements wide"),
})
}
#[inline]
pub fn should_flush_block(&self) -> bool {
self.filled == self.buf.len() - 3
}
/// Returns true if there are no bytes in this ReadBuf
#[inline]
pub fn is_empty(&self) -> bool {
self.filled == 0
}
/// Clears the buffer, resetting the filled region to empty.
///
/// The number of initialized bytes is not changed, and the contents of the buffer are not modified.
#[inline]
pub fn clear(&mut self) {
self.buf.as_mut_slice().fill(0);
self.filled = 0;
}
#[inline(always)]
pub fn push_lit(&mut self, byte: u8) {
// NOTE: we rely on the buffer being zeroed here!
self.buf.as_mut_slice()[self.filled + 2] = byte;
self.filled += 3;
}
#[inline(always)]
pub fn push_dist(&mut self, dist: u16, len: u8) {
let buf = &mut self.buf.as_mut_slice()[self.filled..][..3];
let [dist1, dist2] = dist.to_le_bytes();
buf[0] = dist1;
buf[1] = dist2;
buf[2] = len;
self.filled += 3;
}
pub(crate) unsafe fn from_raw_parts(ptr: *mut u8, lit_bufsize: usize) -> Self {
Self {
buf: unsafe { WeakSliceMut::from_raw_parts_mut(ptr, lit_bufsize * 3) },
filled: 0,
}
}
pub(crate) unsafe fn clone_to(&self, ptr: *mut u8) -> Self {
unsafe { ptr.copy_from_nonoverlapping(self.buf.as_ptr(), self.buf.len()) };
Self {
buf: unsafe { WeakSliceMut::from_raw_parts_mut(ptr, self.buf.len()) },
filled: self.filled,
}
}
}