68 lines
2.1 KiB
Rust
68 lines
2.1 KiB
Rust
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use super::{ArrayLength, Block};
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use core::slice;
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/// Sealed trait for buffer kinds.
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pub trait Sealed {
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/// Invariant guaranteed by a buffer kind, i.e. with correct
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/// buffer code this function always returns true.
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fn invariant(pos: usize, block_size: usize) -> bool;
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/// Split input data into slice of blocks and tail.
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fn split_blocks<N: ArrayLength<u8>>(data: &[u8]) -> (&[Block<N>], &[u8]);
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}
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impl Sealed for super::Eager {
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#[inline(always)]
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fn invariant(pos: usize, block_size: usize) -> bool {
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pos < block_size
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}
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#[inline(always)]
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fn split_blocks<N: ArrayLength<u8>>(data: &[u8]) -> (&[Block<N>], &[u8]) {
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let nb = data.len() / N::USIZE;
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let blocks_len = nb * N::USIZE;
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let tail_len = data.len() - blocks_len;
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// SAFETY: we guarantee that created slices do not point
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// outside of `data`
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unsafe {
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let blocks_ptr = data.as_ptr() as *const Block<N>;
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let tail_ptr = data.as_ptr().add(blocks_len);
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(
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slice::from_raw_parts(blocks_ptr, nb),
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slice::from_raw_parts(tail_ptr, tail_len),
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)
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}
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}
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}
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impl Sealed for super::Lazy {
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#[inline(always)]
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fn invariant(pos: usize, block_size: usize) -> bool {
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pos <= block_size
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}
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#[inline(always)]
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fn split_blocks<N: ArrayLength<u8>>(data: &[u8]) -> (&[Block<N>], &[u8]) {
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if data.is_empty() {
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return (&[], &[]);
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}
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let (nb, tail_len) = if data.len() % N::USIZE == 0 {
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(data.len() / N::USIZE - 1, N::USIZE)
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} else {
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let nb = data.len() / N::USIZE;
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(nb, data.len() - nb * N::USIZE)
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};
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let blocks_len = nb * N::USIZE;
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// SAFETY: we guarantee that created slices do not point
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// outside of `data`
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unsafe {
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let blocks_ptr = data.as_ptr() as *const Block<N>;
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let tail_ptr = data.as_ptr().add(blocks_len);
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(
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slice::from_raw_parts(blocks_ptr, nb),
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slice::from_raw_parts(tail_ptr, tail_len),
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)
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}
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}
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}
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