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use crate::weak_slice::WeakSliceMut;
#[derive(Debug)]
pub struct Window<'a> {
// the full window allocation. This is longer than w_size so that operations don't need to
// perform bounds checks.
buf: WeakSliceMut<'a, u8>,
window_bits: usize,
}
impl<'a> Window<'a> {
pub unsafe fn from_raw_parts(ptr: *mut u8, window_bits: usize) -> Self {
let len = (1 << window_bits) * 2;
let buf = unsafe { WeakSliceMut::from_raw_parts_mut(ptr, len) };
Self { buf, window_bits }
}
pub fn as_ptr(&self) -> *const u8 {
self.buf.as_ptr()
}
pub fn capacity(&self) -> usize {
2 * (1 << self.window_bits)
}
/// Returns a shared reference to the filled portion of the buffer.
#[inline]
pub fn filled(&self) -> &[u8] {
// SAFETY: `self.buf` has been initialized for at least `filled` elements
unsafe { core::slice::from_raw_parts(self.buf.as_ptr().cast(), self.buf.len()) }
}
/// Returns a mutable reference to the filled portion of the buffer.
#[inline]
pub fn filled_mut(&mut self) -> &mut [u8] {
// SAFETY: `self.buf` has been initialized for at least `filled` elements
unsafe { core::slice::from_raw_parts_mut(self.buf.as_mut_ptr().cast(), self.buf.len()) }
}
/// # Safety
///
/// `src` must point to `range.end - range.start` valid (initialized!) bytes
pub unsafe fn copy_and_initialize(&mut self, range: core::ops::Range<usize>, src: *const u8) {
let (start, end) = (range.start, range.end);
let dst = self.buf.as_mut_slice()[range].as_mut_ptr();
unsafe { core::ptr::copy_nonoverlapping(src, dst, end - start) };
}
}