Source code
Revision control
Copy as Markdown
Other Tools
pub fn slide_hash(state: &mut crate::deflate::State) {
let wsize = state.w_size as u16;
slide_hash_chain(state.head.as_mut_slice(), wsize);
slide_hash_chain(state.prev.as_mut_slice(), wsize);
}
fn slide_hash_chain(table: &mut [u16], wsize: u16) {
#[cfg(target_arch = "x86_64")]
if crate::cpu_features::is_enabled_avx2() {
return avx2::slide_hash_chain(table, wsize);
}
#[cfg(target_arch = "aarch64")]
if crate::cpu_features::is_enabled_neon() {
return neon::slide_hash_chain(table, wsize);
}
#[cfg(target_arch = "wasm32")]
if crate::cpu_features::is_enabled_simd128() {
return wasm::slide_hash_chain(table, wsize);
}
rust::slide_hash_chain(table, wsize);
}
mod rust {
pub fn slide_hash_chain(table: &mut [u16], wsize: u16) {
for m in table.iter_mut() {
*m = m.saturating_sub(wsize);
}
}
}
/// # Safety
///
/// These functions should only be executed on `aarch64` systems with the `neon` feature enabled.
#[cfg(target_arch = "aarch64")]
mod neon {
use core::arch::aarch64::{
uint16x8_t, uint16x8x4_t, vdupq_n_u16, vld1q_u16_x4, vqsubq_u16, vst1q_u16_x4,
};
pub fn slide_hash_chain(table: &mut [u16], wsize: u16) {
assert!(crate::cpu_features::is_enabled_neon());
unsafe { slide_hash_chain_internal(table, wsize) }
}
/// # Safety
///
/// Behavior is undefined if the `neon` target feature is not enabled
#[target_feature(enable = "neon")]
unsafe fn slide_hash_chain_internal(table: &mut [u16], wsize: u16) {
debug_assert_eq!(table.len() % 32, 0);
let v = unsafe { vdupq_n_u16(wsize) };
for chunk in table.chunks_exact_mut(32) {
unsafe {
let p0 = vld1q_u16_x4(chunk.as_ptr());
let p0 = vqsubq_u16_x4_x1(p0, v);
vst1q_u16_x4(chunk.as_mut_ptr(), p0);
}
}
}
/// # Safety
///
/// Behavior is undefined if the `neon` target feature is not enabled
#[target_feature(enable = "neon")]
unsafe fn vqsubq_u16_x4_x1(a: uint16x8x4_t, b: uint16x8_t) -> uint16x8x4_t {
unsafe {
uint16x8x4_t(
vqsubq_u16(a.0, b),
vqsubq_u16(a.1, b),
vqsubq_u16(a.2, b),
vqsubq_u16(a.3, b),
)
}
}
}
#[cfg(target_arch = "x86_64")]
mod avx2 {
use core::arch::x86_64::{
__m256i, _mm256_loadu_si256, _mm256_set1_epi16, _mm256_storeu_si256, _mm256_subs_epu16,
};
pub fn slide_hash_chain(table: &mut [u16], wsize: u16) {
assert!(crate::cpu_features::is_enabled_avx2());
unsafe { slide_hash_chain_internal(table, wsize) }
}
/// # Safety
///
/// Behavior is undefined if the `avx` target feature is not enabled
#[target_feature(enable = "avx2")]
unsafe fn slide_hash_chain_internal(table: &mut [u16], wsize: u16) {
debug_assert_eq!(table.len() % 16, 0);
let ymm_wsize = unsafe { _mm256_set1_epi16(wsize as i16) };
for chunk in table.chunks_exact_mut(16) {
let chunk = chunk.as_mut_ptr() as *mut __m256i;
unsafe {
let value = _mm256_loadu_si256(chunk);
let result = _mm256_subs_epu16(value, ymm_wsize);
_mm256_storeu_si256(chunk, result);
}
}
}
}
#[cfg(target_arch = "wasm32")]
mod wasm {
use core::arch::wasm32::{u16x8_splat, u16x8_sub_sat, v128, v128_load, v128_store};
pub fn slide_hash_chain(table: &mut [u16], wsize: u16) {
assert_eq!(table.len() % 8, 0);
slide_hash_chain_internal(table, wsize)
}
#[target_feature(enable = "simd128")]
fn slide_hash_chain_internal(table: &mut [u16], wsize: u16) {
let wsize_v128 = u16x8_splat(wsize);
for chunk in table.chunks_exact_mut(8) {
let chunk_ptr = chunk.as_mut_ptr() as *mut v128;
// Load the 128-bit value.
// SAFETY: the pointer we get from chunks_exact_mut() is valid.
let value = unsafe { v128_load(chunk_ptr) };
// Perform saturating subtraction
let result = u16x8_sub_sat(value, wsize_v128);
// Store the result back.
// SAFETY: the pointer we get from chunks_exact_mut() is valid.
unsafe { v128_store(chunk_ptr, result) };
}
}
}
#[cfg(test)]
mod tests {
use super::*;
const WSIZE: u16 = 32768;
const INPUT: [u16; 64] = [
0, 0, 28790, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 43884, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 64412, 0, 0, 0, 0, 0, 21043, 0, 0, 0, 0, 0, 23707, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 64026, 0, 0, 20182,
];
const OUTPUT: [u16; 64] = [
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11116, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 31644, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 31258, 0, 0, 0,
];
#[test]
fn test_slide_hash_rust() {
let mut input = INPUT;
rust::slide_hash_chain(&mut input, WSIZE);
assert_eq!(input, OUTPUT);
}
#[test]
#[cfg(target_arch = "x86_64")]
fn test_slide_hash_avx2() {
if crate::cpu_features::is_enabled_avx2() {
let mut input = INPUT;
avx2::slide_hash_chain(&mut input, WSIZE);
assert_eq!(input, OUTPUT);
}
}
#[test]
#[cfg(target_arch = "aarch64")]
fn test_slide_hash_neon() {
if crate::cpu_features::is_enabled_neon() {
let mut input = INPUT;
neon::slide_hash_chain(&mut input, WSIZE);
assert_eq!(input, OUTPUT);
}
}
#[test]
#[cfg(target_arch = "wasm32")]
fn test_slide_hash_neon() {
if crate::cpu_features::is_enabled_simd128() {
let mut input = INPUT;
wasm::slide_hash_chain(&mut input, WSIZE);
assert_eq!(input, OUTPUT);
}
}
quickcheck::quickcheck! {
fn slide_is_rust_slide(v: Vec<u16>, wsize: u16) -> bool {
// pad to a multiple of 32
let difference = v.len().next_multiple_of(32) - v.len();
let mut v = v;
v.extend(core::iter::repeat(u16::MAX).take(difference));
let mut a = v.clone();
let mut b = v;
rust::slide_hash_chain(&mut a, wsize);
slide_hash_chain(&mut b, wsize);
a == b
}
}
}