123 lines
4.1 KiB
C
123 lines
4.1 KiB
C
/* insert_string.h
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*
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* Copyright 2019 The Chromium Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the Chromium source repository LICENSE file.
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*/
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#ifdef _MSC_VER
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#define INLINE __inline
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#else
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#define INLINE inline
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#endif
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#include "cpu_features.h"
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/* Optimized insert_string block */
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#if defined(CRC32_SIMD_SSE42_PCLMUL) || defined(CRC32_ARMV8_CRC32)
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#define TARGET_CPU_WITH_CRC
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// clang-format off
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#if defined(CRC32_SIMD_SSE42_PCLMUL)
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/* Required to make MSVC bot build pass. */
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#include <smmintrin.h>
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#if defined(__GNUC__) || defined(__clang__)
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#undef TARGET_CPU_WITH_CRC
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#define TARGET_CPU_WITH_CRC __attribute__((target("sse4.2")))
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#endif
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#define _cpu_crc32_u32 _mm_crc32_u32
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#elif defined(CRC32_ARMV8_CRC32)
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#if defined(__clang__)
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#undef TARGET_CPU_WITH_CRC
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#define __crc32cw __builtin_arm_crc32cw
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#endif
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#define _cpu_crc32_u32 __crc32cw
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#if defined(__aarch64__)
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#define TARGET_CPU_WITH_CRC __attribute__((target("crc")))
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#else // !defined(__aarch64__)
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#define TARGET_CPU_WITH_CRC __attribute__((target("armv8-a,crc")))
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#endif // defined(__aarch64__)
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#endif
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// clang-format on
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TARGET_CPU_WITH_CRC
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local INLINE Pos insert_string_optimized(deflate_state* const s,
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const Pos str) {
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Pos ret;
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unsigned *ip, val, h = 0;
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ip = (unsigned*)&s->window[str];
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val = *ip;
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if (s->level >= 6)
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val &= 0xFFFFFF;
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/* Unlike the case of data integrity checks for GZIP format where the
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* polynomial used is defined (https://tools.ietf.org/html/rfc1952#page-11),
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* here it is just a hash function for the hash table used while
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* performing compression.
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*/
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h = _cpu_crc32_u32(h, val);
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ret = s->head[h & s->hash_mask];
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s->head[h & s->hash_mask] = str;
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s->prev[str & s->w_mask] = ret;
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return ret;
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}
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#endif /* Optimized insert_string block */
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/* ===========================================================================
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* Update a hash value with the given input byte
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* IN assertion: all calls to UPDATE_HASH are made with consecutive input
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* characters, so that a running hash key can be computed from the previous
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* key instead of complete recalculation each time.
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*/
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#define UPDATE_HASH(s, h, c) (h = (((h) << s->hash_shift) ^ (c)) & s->hash_mask)
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/* ===========================================================================
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* Insert string str in the dictionary and set match_head to the previous head
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* of the hash chain (the most recent string with same hash key). Return
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* the previous length of the hash chain.
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* If this file is compiled with -DFASTEST, the compression level is forced
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* to 1, and no hash chains are maintained.
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* IN assertion: all calls to INSERT_STRING are made with consecutive input
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* characters and the first MIN_MATCH bytes of str are valid (except for
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* the last MIN_MATCH-1 bytes of the input file).
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*/
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local INLINE Pos insert_string_c(deflate_state* const s, const Pos str) {
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Pos ret;
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UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH - 1)]);
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#ifdef FASTEST
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ret = s->head[s->ins_h];
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#else
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ret = s->prev[str & s->w_mask] = s->head[s->ins_h];
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#endif
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s->head[s->ins_h] = str;
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return ret;
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}
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local INLINE Pos insert_string(deflate_state* const s, const Pos str) {
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/* String dictionary insertion: faster symbol hashing has a positive impact
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* on data compression speeds (around 20% on Intel and 36% on Arm Cortex big
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* cores).
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* A misfeature is that the generated compressed output will differ from
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* vanilla zlib (even though it is still valid 'DEFLATE-d' content).
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*
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* We offer here a way to disable the optimization if there is the expectation
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* that compressed content should match when compared to vanilla zlib.
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*/
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#if !defined(CHROMIUM_ZLIB_NO_CASTAGNOLI)
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/* TODO(cavalcantii): unify CPU features code. */
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#if defined(CRC32_ARMV8_CRC32)
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if (arm_cpu_enable_crc32)
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return insert_string_optimized(s, str);
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#elif defined(CRC32_SIMD_SSE42_PCLMUL)
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if (x86_cpu_enable_simd)
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return insert_string_optimized(s, str);
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#endif
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#endif
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return insert_string_c(s, str);
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}
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