mirror of
https://github.com/GerbilSoft/zlib-ng.git
synced 2025-06-18 11:35:35 -04:00
bf05e882b8
- Remove obsolete checks - Fix checks that are inconsistent - Stop compiling compare256/longest_match variants that never gets called - Improve how the generic compare256 functions are handled. - Allow overriding OPTIMAL_CMP This simplifies the code and avoids having a lot of code in the compiled library than can never get executed.
134 lines
3.3 KiB
C
134 lines
3.3 KiB
C
/* compare256_rle.h -- 256 byte run-length encoding comparison
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* Copyright (C) 2022 Nathan Moinvaziri
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* For conditions of distribution and use, see copyright notice in zlib.h
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*/
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#include "zbuild.h"
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#include "zmemory.h"
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#include "fallback_builtins.h"
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typedef uint32_t (*compare256_rle_func)(const uint8_t* src0, const uint8_t* src1);
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/* 8-bit integer comparison */
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static inline uint32_t compare256_rle_8(const uint8_t *src0, const uint8_t *src1) {
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uint32_t len = 0;
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do {
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if (*src0 != *src1)
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return len;
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src1 += 1, len += 1;
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if (*src0 != *src1)
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return len;
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src1 += 1, len += 1;
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if (*src0 != *src1)
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return len;
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src1 += 1, len += 1;
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if (*src0 != *src1)
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return len;
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src1 += 1, len += 1;
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if (*src0 != *src1)
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return len;
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src1 += 1, len += 1;
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if (*src0 != *src1)
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return len;
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src1 += 1, len += 1;
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if (*src0 != *src1)
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return len;
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src1 += 1, len += 1;
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if (*src0 != *src1)
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return len;
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src1 += 1, len += 1;
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} while (len < 256);
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return 256;
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}
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/* 16-bit integer comparison */
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static inline uint32_t compare256_rle_16(const uint8_t *src0, const uint8_t *src1) {
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uint32_t len = 0;
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uint16_t src0_cmp;
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src0_cmp = zng_memread_2(src0);
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do {
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if (src0_cmp != zng_memread_2(src1))
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return len + (*src0 == *src1);
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src1 += 2, len += 2;
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if (src0_cmp != zng_memread_2(src1))
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return len + (*src0 == *src1);
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src1 += 2, len += 2;
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if (src0_cmp != zng_memread_2(src1))
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return len + (*src0 == *src1);
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src1 += 2, len += 2;
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if (src0_cmp != zng_memread_2(src1))
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return len + (*src0 == *src1);
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src1 += 2, len += 2;
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} while (len < 256);
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return 256;
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}
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#ifdef HAVE_BUILTIN_CTZ
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/* 32-bit integer comparison */
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static inline uint32_t compare256_rle_32(const uint8_t *src0, const uint8_t *src1) {
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uint32_t sv, len = 0;
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uint16_t src0_cmp;
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src0_cmp = zng_memread_2(src0);
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sv = ((uint32_t)src0_cmp << 16) | src0_cmp;
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do {
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uint32_t mv, diff;
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mv = zng_memread_4(src1);
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diff = sv ^ mv;
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if (diff) {
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#if BYTE_ORDER == LITTLE_ENDIAN
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uint32_t match_byte = __builtin_ctz(diff) / 8;
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#else
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uint32_t match_byte = __builtin_clz(diff) / 8;
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#endif
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return len + match_byte;
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}
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src1 += 4, len += 4;
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} while (len < 256);
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return 256;
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}
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#endif
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#ifdef HAVE_BUILTIN_CTZLL
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/* 64-bit integer comparison */
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static inline uint32_t compare256_rle_64(const uint8_t *src0, const uint8_t *src1) {
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uint32_t src0_cmp32, len = 0;
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uint16_t src0_cmp;
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uint64_t sv;
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src0_cmp = zng_memread_2(src0);
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src0_cmp32 = ((uint32_t)src0_cmp << 16) | src0_cmp;
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sv = ((uint64_t)src0_cmp32 << 32) | src0_cmp32;
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do {
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uint64_t mv, diff;
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mv = zng_memread_8(src1);
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diff = sv ^ mv;
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if (diff) {
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#if BYTE_ORDER == LITTLE_ENDIAN
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uint64_t match_byte = __builtin_ctzll(diff) / 8;
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#else
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uint64_t match_byte = __builtin_clzll(diff) / 8;
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#endif
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return len + (uint32_t)match_byte;
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}
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src1 += 8, len += 8;
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} while (len < 256);
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return 256;
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}
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#endif
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