1//! Buffer wrappers implementing default so we can allocate the buffers with `Box::default()`
2//! to avoid stack copies. Box::new() doesn't at the moment, and using a vec means we would lose
3//! static length info.
4
5use crate::deflate::core::{LZ_DICT_SIZE, MAX_MATCH_LEN};
6use alloc::boxed::Box;
7use alloc::vec;
8
9/// Size of the buffer of lz77 encoded data.
10pub const LZ_CODE_BUF_SIZE: usize = 64 * 1024;
11pub const LZ_CODE_BUF_MASK: usize = LZ_CODE_BUF_SIZE - 1;
12/// Size of the output buffer.
13pub const OUT_BUF_SIZE: usize = (LZ_CODE_BUF_SIZE * 13) / 10;
14pub const LZ_DICT_FULL_SIZE: usize = LZ_DICT_SIZE + MAX_MATCH_LEN - 1 + 1;
15
16/// Size of hash values in the hash chains.
17pub const LZ_HASH_BITS: i32 = 15;
18/// How many bits to shift when updating the current hash value.
19pub const LZ_HASH_SHIFT: i32 = (LZ_HASH_BITS + 2) / 3;
20/// Size of the chained hash tables.
21pub const LZ_HASH_SIZE: usize = 1 << LZ_HASH_BITS;
22
23#[inline]
24pub const fn update_hash(current_hash: u16, byte: u8) -> u16 {
25 ((current_hash << LZ_HASH_SHIFT) ^ byte as u16) & (LZ_HASH_SIZE as u16 - 1)
26}
27
28pub struct HashBuffers {
29 pub dict: Box<[u8; LZ_DICT_FULL_SIZE]>,
30 pub next: Box<[u16; LZ_DICT_SIZE]>,
31 pub hash: Box<[u16; LZ_DICT_SIZE]>,
32}
33
34impl HashBuffers {
35 #[inline]
36 pub fn reset(&mut self) {
37 self.dict.fill(0);
38 self.next.fill(0);
39 self.hash.fill(0);
40 }
41}
42
43impl Default for HashBuffers {
44 fn default() -> HashBuffers {
45 HashBuffers {
46 dict: vecResult, …>![0; LZ_DICT_FULL_SIZE]
47 .into_boxed_slice()
48 .try_into()
49 .unwrap(),
50 next: vec![0; LZ_DICT_SIZE].into_boxed_slice().try_into().unwrap(),
51 hash: vec![0; LZ_DICT_SIZE].into_boxed_slice().try_into().unwrap(),
52 }
53 }
54}
55
56pub struct LocalBuf {
57 pub b: [u8; OUT_BUF_SIZE],
58}
59
60impl Default for LocalBuf {
61 fn default() -> LocalBuf {
62 LocalBuf {
63 b: [0; OUT_BUF_SIZE],
64 }
65 }
66}
67