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//! Buffer wrappers implementing default so we can allocate the buffers with `Box::default()`
//! to avoid stack copies. Box::new() doesn't at the moment, and using a vec means we would lose
//! static length info.
use crate::deflate::core::{LZ_DICT_SIZE, MAX_MATCH_LEN};
use alloc::boxed::Box;
use alloc::vec;
/// Size of the buffer of lz77 encoded data.
pub const LZ_CODE_BUF_SIZE: usize = 64 * 1024;
pub const LZ_CODE_BUF_MASK: usize = LZ_CODE_BUF_SIZE - 1;
/// Size of the output buffer.
pub const OUT_BUF_SIZE: usize = (LZ_CODE_BUF_SIZE * 13) / 10;
pub const LZ_DICT_FULL_SIZE: usize = LZ_DICT_SIZE + MAX_MATCH_LEN - 1 + 1;
/// Size of hash values in the hash chains.
pub const LZ_HASH_BITS: i32 = 15;
/// How many bits to shift when updating the current hash value.
pub const LZ_HASH_SHIFT: i32 = (LZ_HASH_BITS + 2) / 3;
/// Size of the chained hash tables.
pub const LZ_HASH_SIZE: usize = 1 << LZ_HASH_BITS;
#[inline]
pub const fn update_hash(current_hash: u16, byte: u8) -> u16 {
((current_hash << LZ_HASH_SHIFT) ^ byte as u16) & (LZ_HASH_SIZE as u16 - 1)
}
pub struct HashBuffers {
pub dict: Box<[u8; LZ_DICT_FULL_SIZE]>,
pub next: Box<[u16; LZ_DICT_SIZE]>,
pub hash: Box<[u16; LZ_DICT_SIZE]>,
}
impl HashBuffers {
#[inline]
pub fn reset(&mut self) {
self.dict.fill(0);
self.next.fill(0);
self.hash.fill(0);
}
}
impl Default for HashBuffers {
fn default() -> HashBuffers {
HashBuffers {
dict: vec![0; LZ_DICT_FULL_SIZE]
.into_boxed_slice()
.try_into()
.unwrap(),
next: vec![0; LZ_DICT_SIZE].into_boxed_slice().try_into().unwrap(),
hash: vec![0; LZ_DICT_SIZE].into_boxed_slice().try_into().unwrap(),
}
}
}
pub struct LocalBuf {
pub b: [u8; OUT_BUF_SIZE],
}
impl Default for LocalBuf {
fn default() -> LocalBuf {
LocalBuf {
b: [0; OUT_BUF_SIZE],
}
}
}
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