1 /* 2 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc. 3 * All rights reserved. 4 * 5 * This source code is licensed under both the BSD-style license (found in the 6 * LICENSE file in the root directory of this source tree) and the GPLv2 (found 7 * in the COPYING file in the root directory of this source tree). 8 * You may select, at your option, one of the above-listed licenses. 9 */ 10 11 /*-************************************* 12 * Dependencies 13 ***************************************/ 14 #include "zstd_compress_literals.h" 15 16 size_t ZSTD_noCompressLiterals (void* dst, size_t dstCapacity, const void* src, size_t srcSize) 17 { 18 BYTE* const ostart = (BYTE* const)dst; 19 U32 const flSize = 1 + (srcSize>31) + (srcSize>4095); 20 21 RETURN_ERROR_IF(srcSize + flSize > dstCapacity, dstSize_tooSmall); 22 23 switch(flSize) 24 { 25 case 1: /* 2 - 1 - 5 */ 26 ostart[0] = (BYTE)((U32)set_basic + (srcSize<<3)); 27 break; 28 case 2: /* 2 - 2 - 12 */ 29 MEM_writeLE16(ostart, (U16)((U32)set_basic + (1<<2) + (srcSize<<4))); 30 break; 31 case 3: /* 2 - 2 - 20 */ 32 MEM_writeLE32(ostart, (U32)((U32)set_basic + (3<<2) + (srcSize<<4))); 33 break; 34 default: /* not necessary : flSize is {1,2,3} */ 35 assert(0); 36 } 37 38 memcpy(ostart + flSize, src, srcSize); 39 return srcSize + flSize; 40 } 41 42 size_t ZSTD_compressRleLiteralsBlock (void* dst, size_t dstCapacity, const void* src, size_t srcSize) 43 { 44 BYTE* const ostart = (BYTE* const)dst; 45 U32 const flSize = 1 + (srcSize>31) + (srcSize>4095); 46 47 (void)dstCapacity; /* dstCapacity already guaranteed to be >=4, hence large enough */ 48 49 switch(flSize) 50 { 51 case 1: /* 2 - 1 - 5 */ 52 ostart[0] = (BYTE)((U32)set_rle + (srcSize<<3)); 53 break; 54 case 2: /* 2 - 2 - 12 */ 55 MEM_writeLE16(ostart, (U16)((U32)set_rle + (1<<2) + (srcSize<<4))); 56 break; 57 case 3: /* 2 - 2 - 20 */ 58 MEM_writeLE32(ostart, (U32)((U32)set_rle + (3<<2) + (srcSize<<4))); 59 break; 60 default: /* not necessary : flSize is {1,2,3} */ 61 assert(0); 62 } 63 64 ostart[flSize] = *(const BYTE*)src; 65 return flSize+1; 66 } 67 68 size_t ZSTD_compressLiterals (ZSTD_hufCTables_t const* prevHuf, 69 ZSTD_hufCTables_t* nextHuf, 70 ZSTD_strategy strategy, int disableLiteralCompression, 71 void* dst, size_t dstCapacity, 72 const void* src, size_t srcSize, 73 void* entropyWorkspace, size_t entropyWorkspaceSize, 74 const int bmi2) 75 { 76 size_t const minGain = ZSTD_minGain(srcSize, strategy); 77 size_t const lhSize = 3 + (srcSize >= 1 KB) + (srcSize >= 16 KB); 78 BYTE* const ostart = (BYTE*)dst; 79 U32 singleStream = srcSize < 256; 80 symbolEncodingType_e hType = set_compressed; 81 size_t cLitSize; 82 83 DEBUGLOG(5,"ZSTD_compressLiterals (disableLiteralCompression=%i)", 84 disableLiteralCompression); 85 86 /* Prepare nextEntropy assuming reusing the existing table */ 87 memcpy(nextHuf, prevHuf, sizeof(*prevHuf)); 88 89 if (disableLiteralCompression) 90 return ZSTD_noCompressLiterals(dst, dstCapacity, src, srcSize); 91 92 /* small ? don't even attempt compression (speed opt) */ 93 # define COMPRESS_LITERALS_SIZE_MIN 63 94 { size_t const minLitSize = (prevHuf->repeatMode == HUF_repeat_valid) ? 6 : COMPRESS_LITERALS_SIZE_MIN; 95 if (srcSize <= minLitSize) return ZSTD_noCompressLiterals(dst, dstCapacity, src, srcSize); 96 } 97 98 RETURN_ERROR_IF(dstCapacity < lhSize+1, dstSize_tooSmall, "not enough space for compression"); 99 { HUF_repeat repeat = prevHuf->repeatMode; 100 int const preferRepeat = strategy < ZSTD_lazy ? srcSize <= 1024 : 0; 101 if (repeat == HUF_repeat_valid && lhSize == 3) singleStream = 1; 102 cLitSize = singleStream ? 103 HUF_compress1X_repeat( 104 ostart+lhSize, dstCapacity-lhSize, src, srcSize, 105 255, 11, entropyWorkspace, entropyWorkspaceSize, 106 (HUF_CElt*)nextHuf->CTable, &repeat, preferRepeat, bmi2) : 107 HUF_compress4X_repeat( 108 ostart+lhSize, dstCapacity-lhSize, src, srcSize, 109 255, 11, entropyWorkspace, entropyWorkspaceSize, 110 (HUF_CElt*)nextHuf->CTable, &repeat, preferRepeat, bmi2); 111 if (repeat != HUF_repeat_none) { 112 /* reused the existing table */ 113 hType = set_repeat; 114 } 115 } 116 117 if ((cLitSize==0) | (cLitSize >= srcSize - minGain) | ERR_isError(cLitSize)) { 118 memcpy(nextHuf, prevHuf, sizeof(*prevHuf)); 119 return ZSTD_noCompressLiterals(dst, dstCapacity, src, srcSize); 120 } 121 if (cLitSize==1) { 122 memcpy(nextHuf, prevHuf, sizeof(*prevHuf)); 123 return ZSTD_compressRleLiteralsBlock(dst, dstCapacity, src, srcSize); 124 } 125 126 if (hType == set_compressed) { 127 /* using a newly constructed table */ 128 nextHuf->repeatMode = HUF_repeat_check; 129 } 130 131 /* Build header */ 132 switch(lhSize) 133 { 134 case 3: /* 2 - 2 - 10 - 10 */ 135 { U32 const lhc = hType + ((!singleStream) << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<14); 136 MEM_writeLE24(ostart, lhc); 137 break; 138 } 139 case 4: /* 2 - 2 - 14 - 14 */ 140 { U32 const lhc = hType + (2 << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<18); 141 MEM_writeLE32(ostart, lhc); 142 break; 143 } 144 case 5: /* 2 - 2 - 18 - 18 */ 145 { U32 const lhc = hType + (3 << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<22); 146 MEM_writeLE32(ostart, lhc); 147 ostart[4] = (BYTE)(cLitSize >> 10); 148 break; 149 } 150 default: /* not possible : lhSize is {3,4,5} */ 151 assert(0); 152 } 153 return lhSize+cLitSize; 154 } 155