59 lines
1.6 KiB
Rust
59 lines
1.6 KiB
Rust
//! 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};
|
|
|
|
/// Size of the buffer of lz77 encoded data.
|
|
pub const LZ_CODE_BUF_SIZE: usize = 64 * 1024;
|
|
/// 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 fn update_hash(current_hash: u16, byte: u8) -> u16 {
|
|
((current_hash << LZ_HASH_SHIFT) ^ u16::from(byte)) & (LZ_HASH_SIZE as u16 - 1)
|
|
}
|
|
|
|
pub struct HashBuffers {
|
|
pub dict: [u8; LZ_DICT_FULL_SIZE],
|
|
pub next: [u16; LZ_DICT_SIZE],
|
|
pub hash: [u16; LZ_DICT_SIZE],
|
|
}
|
|
|
|
impl HashBuffers {
|
|
#[inline]
|
|
pub fn reset(&mut self) {
|
|
*self = HashBuffers::default();
|
|
}
|
|
}
|
|
|
|
impl Default for HashBuffers {
|
|
fn default() -> HashBuffers {
|
|
HashBuffers {
|
|
dict: [0; LZ_DICT_FULL_SIZE],
|
|
next: [0; LZ_DICT_SIZE],
|
|
hash: [0; LZ_DICT_SIZE],
|
|
}
|
|
}
|
|
}
|
|
|
|
pub struct LocalBuf {
|
|
pub b: [u8; OUT_BUF_SIZE],
|
|
}
|
|
|
|
impl Default for LocalBuf {
|
|
fn default() -> LocalBuf {
|
|
LocalBuf {
|
|
b: [0; OUT_BUF_SIZE],
|
|
}
|
|
}
|
|
}
|