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zstd_compress_literals.c File Reference
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Macros

#define COMPRESS_LITERALS_SIZE_MIN   63
 

Functions

size_t ZSTD_noCompressLiterals (void *dst, size_t dstCapacity, const void *src, size_t srcSize)
 
size_t ZSTD_compressRleLiteralsBlock (void *dst, size_t dstCapacity, const void *src, size_t srcSize)
 
size_t ZSTD_compressLiterals (ZSTD_hufCTables_t const *prevHuf, ZSTD_hufCTables_t *nextHuf, ZSTD_strategy strategy, int disableLiteralCompression, void *dst, size_t dstCapacity, const void *src, size_t srcSize, void *entropyWorkspace, size_t entropyWorkspaceSize, const int bmi2)
 

Macro Definition Documentation

◆ COMPRESS_LITERALS_SIZE_MIN

#define COMPRESS_LITERALS_SIZE_MIN   63

Function Documentation

◆ ZSTD_compressLiterals()

size_t ZSTD_compressLiterals ( ZSTD_hufCTables_t const prevHuf,
ZSTD_hufCTables_t nextHuf,
ZSTD_strategy  strategy,
int  disableLiteralCompression,
void dst,
size_t  dstCapacity,
const void src,
size_t  srcSize,
void entropyWorkspace,
size_t  entropyWorkspaceSize,
const int  bmi2 
)

Definition at line 70 of file zstd_compress_literals.c.

77{
78 size_t const minGain = ZSTD_minGain(srcSize, strategy);
79 size_t const lhSize = 3 + (srcSize >= 1 KB) + (srcSize >= 16 KB);
80 BYTE* const ostart = (BYTE*)dst;
81 U32 singleStream = srcSize < 256;
83 size_t cLitSize;
84
85 DEBUGLOG(5,"ZSTD_compressLiterals (disableLiteralCompression=%i srcSize=%u)",
86 disableLiteralCompression, (U32)srcSize);
87
88 /* Prepare nextEntropy assuming reusing the existing table */
89 memcpy(nextHuf, prevHuf, sizeof(*prevHuf));
90
91 if (disableLiteralCompression)
92 return ZSTD_noCompressLiterals(dst, dstCapacity, src, srcSize);
93
94 /* small ? don't even attempt compression (speed opt) */
95# define COMPRESS_LITERALS_SIZE_MIN 63
96 { size_t const minLitSize = (prevHuf->repeatMode == HUF_repeat_valid) ? 6 : COMPRESS_LITERALS_SIZE_MIN;
97 if (srcSize <= minLitSize) return ZSTD_noCompressLiterals(dst, dstCapacity, src, srcSize);
98 }
99
100 RETURN_ERROR_IF(dstCapacity < lhSize+1, dstSize_tooSmall, "not enough space for compression");
101 { HUF_repeat repeat = prevHuf->repeatMode;
102 int const preferRepeat = strategy < ZSTD_lazy ? srcSize <= 1024 : 0;
103 if (repeat == HUF_repeat_valid && lhSize == 3) singleStream = 1;
104 cLitSize = singleStream ?
106 ostart+lhSize, dstCapacity-lhSize, src, srcSize,
107 HUF_SYMBOLVALUE_MAX, HUF_TABLELOG_DEFAULT, entropyWorkspace, entropyWorkspaceSize,
108 (HUF_CElt*)nextHuf->CTable, &repeat, preferRepeat, bmi2) :
110 ostart+lhSize, dstCapacity-lhSize, src, srcSize,
111 HUF_SYMBOLVALUE_MAX, HUF_TABLELOG_DEFAULT, entropyWorkspace, entropyWorkspaceSize,
112 (HUF_CElt*)nextHuf->CTable, &repeat, preferRepeat, bmi2);
113 if (repeat != HUF_repeat_none) {
114 /* reused the existing table */
115 DEBUGLOG(5, "Reusing previous huffman table");
116 hType = set_repeat;
117 }
118 }
119
120 if ((cLitSize==0) | (cLitSize >= srcSize - minGain) | ERR_isError(cLitSize)) {
121 memcpy(nextHuf, prevHuf, sizeof(*prevHuf));
122 return ZSTD_noCompressLiterals(dst, dstCapacity, src, srcSize);
123 }
124 if (cLitSize==1) {
125 memcpy(nextHuf, prevHuf, sizeof(*prevHuf));
126 return ZSTD_compressRleLiteralsBlock(dst, dstCapacity, src, srcSize);
127 }
128
129 if (hType == set_compressed) {
130 /* using a newly constructed table */
131 nextHuf->repeatMode = HUF_repeat_check;
132 }
133
134 /* Build header */
135 switch(lhSize)
136 {
137 case 3: /* 2 - 2 - 10 - 10 */
138 { U32 const lhc = hType + ((!singleStream) << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<14);
139 MEM_writeLE24(ostart, lhc);
140 break;
141 }
142 case 4: /* 2 - 2 - 14 - 14 */
143 { U32 const lhc = hType + (2 << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<18);
144 MEM_writeLE32(ostart, lhc);
145 break;
146 }
147 case 5: /* 2 - 2 - 18 - 18 */
148 { U32 const lhc = hType + (3 << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<22);
149 MEM_writeLE32(ostart, lhc);
150 ostart[4] = (BYTE)(cLitSize >> 10);
151 break;
152 }
153 default: /* not possible : lhSize is {3,4,5} */
154 assert(0);
155 }
156 DEBUGLOG(5, "Compressed literals: %u -> %u", (U32)srcSize, (U32)(lhSize+cLitSize));
157 return lhSize+cLitSize;
158}
#define assert(x)
Definition: debug.h:53
#define DEBUGLOG(l,...)
Definition: debug.h:106
MEM_STATIC void MEM_writeLE32(void *memPtr, U32 val32)
Definition: mem.h:354
MEM_STATIC void MEM_writeLE24(void *memPtr, U32 val)
Definition: mem.h:340
ERR_STATIC unsigned ERR_isError(size_t code)
Definition: error_private.h:56
GLenum src
Definition: glext.h:6340
GLenum GLenum dst
Definition: glext.h:6340
size_t HUF_compress4X_repeat(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, void *workSpace, size_t wkspSize, HUF_CElt *hufTable, HUF_repeat *repeat, int preferRepeat, int bmi2)
Definition: huf_compress.c:775
size_t HUF_compress1X_repeat(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, void *workSpace, size_t wkspSize, HUF_CElt *hufTable, HUF_repeat *repeat, int preferRepeat, int bmi2)
Definition: huf_compress.c:738
#define memcpy(s1, s2, n)
Definition: mkisofs.h:878
#define KB
Definition: setuplib.h:55
U32 CTable[HUF_CTABLE_SIZE_U32(255)]
static int repeat
Definition: xmllint.c:137
unsigned char BYTE
Definition: xxhash.c:193
unsigned int U32
Definition: xxhash.c:195
@ ZSTD_lazy
Definition: zstd.h:254
MEM_STATIC size_t ZSTD_minGain(size_t srcSize, ZSTD_strategy strat)
size_t ZSTD_noCompressLiterals(void *dst, size_t dstCapacity, const void *src, size_t srcSize)
#define COMPRESS_LITERALS_SIZE_MIN
size_t ZSTD_compressRleLiteralsBlock(void *dst, size_t dstCapacity, const void *src, size_t srcSize)
#define RETURN_ERROR_IF(cond, err,...)
Definition: zstd_internal.h:91
symbolEncodingType_e
@ set_repeat
@ set_compressed

Referenced by ZSTD_compressSequences_internal().

◆ ZSTD_compressRleLiteralsBlock()

size_t ZSTD_compressRleLiteralsBlock ( void dst,
size_t  dstCapacity,
const void src,
size_t  srcSize 
)

Definition at line 43 of file zstd_compress_literals.c.

44{
45 BYTE* const ostart = (BYTE* const)dst;
46 U32 const flSize = 1 + (srcSize>31) + (srcSize>4095);
47
48 (void)dstCapacity; /* dstCapacity already guaranteed to be >=4, hence large enough */
49
50 switch(flSize)
51 {
52 case 1: /* 2 - 1 - 5 */
53 ostart[0] = (BYTE)((U32)set_rle + (srcSize<<3));
54 break;
55 case 2: /* 2 - 2 - 12 */
56 MEM_writeLE16(ostart, (U16)((U32)set_rle + (1<<2) + (srcSize<<4)));
57 break;
58 case 3: /* 2 - 2 - 20 */
59 MEM_writeLE32(ostart, (U32)((U32)set_rle + (3<<2) + (srcSize<<4)));
60 break;
61 default: /* not necessary : flSize is {1,2,3} */
62 assert(0);
63 }
64
65 ostart[flSize] = *(const BYTE*)src;
66 DEBUGLOG(5, "RLE literals: %u -> %u", (U32)srcSize, (U32)flSize + 1);
67 return flSize+1;
68}
MEM_STATIC void MEM_writeLE16(void *memPtr, U16 val)
Definition: mem.h:324
unsigned short U16
Definition: xxhash.c:194
@ set_rle

Referenced by ZSTD_compressLiterals(), and ZSTD_compressSubBlock_literal().

◆ ZSTD_noCompressLiterals()

size_t ZSTD_noCompressLiterals ( void dst,
size_t  dstCapacity,
const void src,
size_t  srcSize 
)

Definition at line 16 of file zstd_compress_literals.c.

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 DEBUGLOG(5, "Raw literals: %u -> %u", (U32)srcSize, (U32)(srcSize + flSize));
40 return srcSize + flSize;
41}
@ set_basic

Referenced by ZSTD_compressLiterals(), and ZSTD_compressSubBlock_literal().