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- /* slide_hash_simd.h
- *
- * Copyright 2022 The Chromium Authors. All rights reserved.
- * Use of this source code is governed by a BSD-style license that can be
- * found in the Chromium source repository LICENSE file.
- */
- #ifndef SLIDE_HASH_SIMD_H
- #define SLIDE_HASH_SIMD_H
- #include "deflate.h"
- #ifndef INLINE
- #if defined(_MSC_VER) && !defined(__clang__)
- #define INLINE __inline
- #else
- #define INLINE inline
- #endif
- #endif
- #if defined(CPU_NO_SIMD)
- #error SIMD has been disabled for your build target
- #elif defined(DEFLATE_SLIDE_HASH_SSE2)
- #include <emmintrin.h> /* SSE2 */
- #define Z_SLIDE_INIT_SIMD(wsize) _mm_set1_epi16((ush)(wsize))
- #define Z_SLIDE_HASH_SIMD(table, size, vector_wsize) \
- for (const Posf* const end = table + size; table != end;) { \
- __m128i vO = _mm_loadu_si128((__m128i *)(table + 0)); \
- vO = _mm_subs_epu16(vO, vector_wsize); \
- _mm_storeu_si128((__m128i *)(table + 0), vO); \
- table += 8; \
- }
- typedef __m128i z_vec128i_u16x8_t;
- #elif defined(DEFLATE_SLIDE_HASH_NEON)
- #include <arm_neon.h> /* NEON */
- #define Z_SLIDE_INIT_SIMD(wsize) vdupq_n_u16((ush)(wsize))
- #define Z_SLIDE_HASH_SIMD(table, size, vector_wsize) \
- for (const Posf* const end = table + size; table != end;) { \
- uint16x8_t vO = vld1q_u16(table + 0); \
- uint16x8_t v8 = vld1q_u16(table + 8); \
- vO = vqsubq_u16(vO, vector_wsize); \
- v8 = vqsubq_u16(v8, vector_wsize); \
- vst1q_u16(table + 0, vO); \
- vst1q_u16(table + 8, v8); \
- table += 8 + 8; \
- }
- typedef uint16x8_t z_vec128i_u16x8_t;
- #else
- #error slide_hash_simd is not defined for your build target
- #endif
- /* ===========================================================================
- * Slide the hash table when sliding the window down (could be avoided with 32
- * bit values at the expense of memory usage). We slide even when level == 0 to
- * keep the hash table consistent if we switch back to level > 0 later.
- */
- local INLINE void slide_hash_simd(
- Posf *head, Posf *prev, const uInt w_size, const uInt hash_size) {
- /*
- * The SIMD implementation of the hash table slider assumes:
- *
- * 1. hash chain offset is 2 bytes. Should be true as Pos is "ush" type.
- */
- Assert(sizeof(Pos) == 2, "Pos type size error: should be 2 bytes");
- Assert(sizeof(ush) == 2, "ush type size error: should be 2 bytes");
- Assert(hash_size <= (1 << 16), "Hash table maximum size error");
- Assert(hash_size >= (1 << 8), "Hash table minimum size error");
- Assert(w_size == (ush)w_size, "Prev table size error");
- /*
- * 2. The hash & prev table sizes are a multiple of 32 bytes (256 bits),
- * since the NEON table slider moves two 128-bit items per loop (loop is
- * unrolled on NEON for performance, see http://crbug.com/863257).
- */
- Assert(!((hash_size * sizeof(head[0])) & (32 - 1)),
- "Hash table size error: should be a multiple of 32 bytes");
- Assert(!((w_size * sizeof(prev[0])) & (32 - 1)),
- "Prev table size error: should be a multiple of 32 bytes");
- /*
- * Duplicate (ush)w_size in each uint16_t component of a 128-bit vector.
- */
- const z_vec128i_u16x8_t vec_wsize = Z_SLIDE_INIT_SIMD(w_size);
- /*
- * Slide {head,prev} hash chain values: subtracts (ush)w_size from every
- * value with a saturating SIMD subtract, to clamp the result to 0(NIL),
- * to implement slide_hash() `(m >= wsize ? m - wsize : NIL);` code.
- */
- Z_SLIDE_HASH_SIMD(head, hash_size, vec_wsize);
- #ifndef FASTEST
- Z_SLIDE_HASH_SIMD(prev, w_size, vec_wsize);
- #endif
- }
- #undef z_vec128i_u16x8_t
- #undef Z_SLIDE_HASH_SIMD
- #undef Z_SLIDE_INIT_SIMD
- #endif /* SLIDE_HASH_SIMD_H */
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