OLD | NEW |
1 /* Copyright 2015 Google Inc. All Rights Reserved. | 1 /* Copyright 2015 Google Inc. All Rights Reserved. |
2 | 2 |
3 Distributed under MIT license. | 3 Distributed under MIT license. |
4 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT | 4 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT |
5 */ | 5 */ |
6 | 6 |
7 // Function for fast encoding of an input fragment, independently from the input | 7 /* Function for fast encoding of an input fragment, independently from the input |
8 // history. This function uses one-pass processing: when we find a backward | 8 history. This function uses one-pass processing: when we find a backward |
9 // match, we immediately emit the corresponding command and literal codes to | 9 match, we immediately emit the corresponding command and literal codes to |
10 // the bit stream. | 10 the bit stream. |
11 // | 11 |
12 // Adapted from the CompressFragment() function in | 12 Adapted from the CompressFragment() function in |
13 // https://github.com/google/snappy/blob/master/snappy.cc | 13 https://github.com/google/snappy/blob/master/snappy.cc */ |
14 | 14 |
15 #include "./compress_fragment.h" | 15 #include "./compress_fragment.h" |
16 | 16 |
17 #include <algorithm> | 17 #include <string.h> /* memcmp, memcpy, memset */ |
18 #include <cstring> | 18 |
19 | 19 #include "../common/constants.h" |
| 20 #include <brotli/types.h> |
20 #include "./brotli_bit_stream.h" | 21 #include "./brotli_bit_stream.h" |
21 #include "./entropy_encode.h" | 22 #include "./entropy_encode.h" |
22 #include "./fast_log.h" | 23 #include "./fast_log.h" |
23 #include "./find_match_length.h" | 24 #include "./find_match_length.h" |
| 25 #include "./memory.h" |
24 #include "./port.h" | 26 #include "./port.h" |
25 #include "./types.h" | |
26 #include "./write_bits.h" | 27 #include "./write_bits.h" |
27 | 28 |
28 namespace brotli { | 29 |
29 | 30 #if defined(__cplusplus) || defined(c_plusplus) |
30 // kHashMul32 multiplier has these properties: | 31 extern "C" { |
31 // * The multiplier must be odd. Otherwise we may lose the highest bit. | 32 #endif |
32 // * No long streaks of 1s or 0s. | 33 |
33 // * There is no effort to ensure that it is a prime, the oddity is enough | 34 /* Same as MaxBackwardLimit(18) */ |
34 // for this use. | 35 #define MAX_DISTANCE ((1 << 18) - BROTLI_WINDOW_GAP) |
35 // * The number has been tuned heuristically against compression benchmarks. | 36 |
| 37 /* kHashMul32 multiplier has these properties: |
| 38 * The multiplier must be odd. Otherwise we may lose the highest bit. |
| 39 * No long streaks of ones or zeros. |
| 40 * There is no effort to ensure that it is a prime, the oddity is enough |
| 41 for this use. |
| 42 * The number has been tuned heuristically against compression benchmarks. */ |
36 static const uint32_t kHashMul32 = 0x1e35a7bd; | 43 static const uint32_t kHashMul32 = 0x1e35a7bd; |
37 | 44 |
38 static inline uint32_t Hash(const uint8_t* p, size_t shift) { | 45 static BROTLI_INLINE uint32_t Hash(const uint8_t* p, size_t shift) { |
39 const uint64_t h = (BROTLI_UNALIGNED_LOAD64(p) << 24) * kHashMul32; | 46 const uint64_t h = (BROTLI_UNALIGNED_LOAD64(p) << 24) * kHashMul32; |
40 return static_cast<uint32_t>(h >> shift); | 47 return (uint32_t)(h >> shift); |
41 } | 48 } |
42 | 49 |
43 static inline uint32_t HashBytesAtOffset(uint64_t v, int offset, size_t shift) { | 50 static BROTLI_INLINE uint32_t HashBytesAtOffset( |
| 51 uint64_t v, int offset, size_t shift) { |
44 assert(offset >= 0); | 52 assert(offset >= 0); |
45 assert(offset <= 3); | 53 assert(offset <= 3); |
46 const uint64_t h = ((v >> (8 * offset)) << 24) * kHashMul32; | 54 { |
47 return static_cast<uint32_t>(h >> shift); | 55 const uint64_t h = ((v >> (8 * offset)) << 24) * kHashMul32; |
48 } | 56 return (uint32_t)(h >> shift); |
49 | 57 } |
50 static inline int IsMatch(const uint8_t* p1, const uint8_t* p2) { | 58 } |
51 return (BROTLI_UNALIGNED_LOAD32(p1) == BROTLI_UNALIGNED_LOAD32(p2) && | 59 |
52 p1[4] == p2[4]); | 60 static BROTLI_INLINE BROTLI_BOOL IsMatch(const uint8_t* p1, const uint8_t* p2) { |
53 } | 61 return TO_BROTLI_BOOL( |
54 | 62 BROTLI_UNALIGNED_LOAD32(p1) == BROTLI_UNALIGNED_LOAD32(p2) && |
55 // Builds a literal prefix code into "depths" and "bits" based on the statistics | 63 p1[4] == p2[4]); |
56 // of the "input" string and stores it into the bit stream. | 64 } |
57 // Note that the prefix code here is built from the pre-LZ77 input, therefore | 65 |
58 // we can only approximate the statistics of the actual literal stream. | 66 /* Builds a literal prefix code into "depths" and "bits" based on the statistics |
59 // Moreover, for long inputs we build a histogram from a sample of the input | 67 of the "input" string and stores it into the bit stream. |
60 // and thus have to assign a non-zero depth for each literal. | 68 Note that the prefix code here is built from the pre-LZ77 input, therefore |
61 static void BuildAndStoreLiteralPrefixCode(const uint8_t* input, | 69 we can only approximate the statistics of the actual literal stream. |
62 const size_t input_size, | 70 Moreover, for long inputs we build a histogram from a sample of the input |
63 uint8_t depths[256], | 71 and thus have to assign a non-zero depth for each literal. |
64 uint16_t bits[256], | 72 Returns estimated compression ratio millibytes/char for encoding given input |
65 size_t* storage_ix, | 73 with generated code. */ |
66 uint8_t* storage) { | 74 static size_t BuildAndStoreLiteralPrefixCode(MemoryManager* m, |
| 75 const uint8_t* input, |
| 76 const size_t input_size, |
| 77 uint8_t depths[256], |
| 78 uint16_t bits[256], |
| 79 size_t* storage_ix, |
| 80 uint8_t* storage) { |
67 uint32_t histogram[256] = { 0 }; | 81 uint32_t histogram[256] = { 0 }; |
68 size_t histogram_total; | 82 size_t histogram_total; |
| 83 size_t i; |
69 if (input_size < (1 << 15)) { | 84 if (input_size < (1 << 15)) { |
70 for (size_t i = 0; i < input_size; ++i) { | 85 for (i = 0; i < input_size; ++i) { |
71 ++histogram[input[i]]; | 86 ++histogram[input[i]]; |
72 } | 87 } |
73 histogram_total = input_size; | 88 histogram_total = input_size; |
74 for (size_t i = 0; i < 256; ++i) { | 89 for (i = 0; i < 256; ++i) { |
75 // We weigh the first 11 samples with weight 3 to account for the | 90 /* We weigh the first 11 samples with weight 3 to account for the |
76 // balancing effect of the LZ77 phase on the histogram. | 91 balancing effect of the LZ77 phase on the histogram. */ |
77 const uint32_t adjust = 2 * std::min(histogram[i], 11u); | 92 const uint32_t adjust = 2 * BROTLI_MIN(uint32_t, histogram[i], 11u); |
78 histogram[i] += adjust; | 93 histogram[i] += adjust; |
79 histogram_total += adjust; | 94 histogram_total += adjust; |
80 } | 95 } |
81 } else { | 96 } else { |
82 static const size_t kSampleRate = 29; | 97 static const size_t kSampleRate = 29; |
83 for (size_t i = 0; i < input_size; i += kSampleRate) { | 98 for (i = 0; i < input_size; i += kSampleRate) { |
84 ++histogram[input[i]]; | 99 ++histogram[input[i]]; |
85 } | 100 } |
86 histogram_total = (input_size + kSampleRate - 1) / kSampleRate; | 101 histogram_total = (input_size + kSampleRate - 1) / kSampleRate; |
87 for (size_t i = 0; i < 256; ++i) { | 102 for (i = 0; i < 256; ++i) { |
88 // We add 1 to each population count to avoid 0 bit depths (since this is | 103 /* We add 1 to each population count to avoid 0 bit depths (since this is |
89 // only a sample and we don't know if the symbol appears or not), and we | 104 only a sample and we don't know if the symbol appears or not), and we |
90 // weigh the first 11 samples with weight 3 to account for the balancing | 105 weigh the first 11 samples with weight 3 to account for the balancing |
91 // effect of the LZ77 phase on the histogram (more frequent symbols are | 106 effect of the LZ77 phase on the histogram (more frequent symbols are |
92 // more likely to be in backward references instead as literals). | 107 more likely to be in backward references instead as literals). */ |
93 const uint32_t adjust = 1 + 2 * std::min(histogram[i], 11u); | 108 const uint32_t adjust = 1 + 2 * BROTLI_MIN(uint32_t, histogram[i], 11u); |
94 histogram[i] += adjust; | 109 histogram[i] += adjust; |
95 histogram_total += adjust; | 110 histogram_total += adjust; |
96 } | 111 } |
97 } | 112 } |
98 BuildAndStoreHuffmanTreeFast(histogram, histogram_total, | 113 BrotliBuildAndStoreHuffmanTreeFast(m, histogram, histogram_total, |
99 /* max_bits = */ 8, | 114 /* max_bits = */ 8, |
100 depths, bits, storage_ix, storage); | 115 depths, bits, storage_ix, storage); |
101 } | 116 if (BROTLI_IS_OOM(m)) return 0; |
102 | 117 { |
103 // Builds a command and distance prefix code (each 64 symbols) into "depth" and | 118 size_t literal_ratio = 0; |
104 // "bits" based on "histogram" and stores it into the bit stream. | 119 for (i = 0; i < 256; ++i) { |
| 120 if (histogram[i]) literal_ratio += histogram[i] * depths[i]; |
| 121 } |
| 122 /* Estimated encoding ratio, millibytes per symbol. */ |
| 123 return (literal_ratio * 125) / histogram_total; |
| 124 } |
| 125 } |
| 126 |
| 127 /* Builds a command and distance prefix code (each 64 symbols) into "depth" and |
| 128 "bits" based on "histogram" and stores it into the bit stream. */ |
105 static void BuildAndStoreCommandPrefixCode(const uint32_t histogram[128], | 129 static void BuildAndStoreCommandPrefixCode(const uint32_t histogram[128], |
106 uint8_t depth[128], | 130 uint8_t depth[128], uint16_t bits[128], size_t* storage_ix, |
107 uint16_t bits[128], | 131 uint8_t* storage) { |
108 size_t* storage_ix, | 132 /* Tree size for building a tree over 64 symbols is 2 * 64 + 1. */ |
109 uint8_t* storage) { | 133 HuffmanTree tree[129]; |
110 // Tree size for building a tree over 64 symbols is 2 * 64 + 1. | 134 uint8_t cmd_depth[BROTLI_NUM_COMMAND_SYMBOLS] = { 0 }; |
111 static const size_t kTreeSize = 129; | |
112 HuffmanTree tree[kTreeSize]; | |
113 CreateHuffmanTree(histogram, 64, 15, tree, depth); | |
114 CreateHuffmanTree(&histogram[64], 64, 14, tree, &depth[64]); | |
115 // We have to jump through a few hoopes here in order to compute | |
116 // the command bits because the symbols are in a different order than in | |
117 // the full alphabet. This looks complicated, but having the symbols | |
118 // in this order in the command bits saves a few branches in the Emit* | |
119 // functions. | |
120 uint8_t cmd_depth[64]; | |
121 uint16_t cmd_bits[64]; | 135 uint16_t cmd_bits[64]; |
| 136 |
| 137 BrotliCreateHuffmanTree(histogram, 64, 15, tree, depth); |
| 138 BrotliCreateHuffmanTree(&histogram[64], 64, 14, tree, &depth[64]); |
| 139 /* We have to jump through a few hoops here in order to compute |
| 140 the command bits because the symbols are in a different order than in |
| 141 the full alphabet. This looks complicated, but having the symbols |
| 142 in this order in the command bits saves a few branches in the Emit* |
| 143 functions. */ |
122 memcpy(cmd_depth, depth, 24); | 144 memcpy(cmd_depth, depth, 24); |
123 memcpy(cmd_depth + 24, depth + 40, 8); | 145 memcpy(cmd_depth + 24, depth + 40, 8); |
124 memcpy(cmd_depth + 32, depth + 24, 8); | 146 memcpy(cmd_depth + 32, depth + 24, 8); |
125 memcpy(cmd_depth + 40, depth + 48, 8); | 147 memcpy(cmd_depth + 40, depth + 48, 8); |
126 memcpy(cmd_depth + 48, depth + 32, 8); | 148 memcpy(cmd_depth + 48, depth + 32, 8); |
127 memcpy(cmd_depth + 56, depth + 56, 8); | 149 memcpy(cmd_depth + 56, depth + 56, 8); |
128 ConvertBitDepthsToSymbols(cmd_depth, 64, cmd_bits); | 150 BrotliConvertBitDepthsToSymbols(cmd_depth, 64, cmd_bits); |
129 memcpy(bits, cmd_bits, 48); | 151 memcpy(bits, cmd_bits, 48); |
130 memcpy(bits + 24, cmd_bits + 32, 16); | 152 memcpy(bits + 24, cmd_bits + 32, 16); |
131 memcpy(bits + 32, cmd_bits + 48, 16); | 153 memcpy(bits + 32, cmd_bits + 48, 16); |
132 memcpy(bits + 40, cmd_bits + 24, 16); | 154 memcpy(bits + 40, cmd_bits + 24, 16); |
133 memcpy(bits + 48, cmd_bits + 40, 16); | 155 memcpy(bits + 48, cmd_bits + 40, 16); |
134 memcpy(bits + 56, cmd_bits + 56, 16); | 156 memcpy(bits + 56, cmd_bits + 56, 16); |
135 ConvertBitDepthsToSymbols(&depth[64], 64, &bits[64]); | 157 BrotliConvertBitDepthsToSymbols(&depth[64], 64, &bits[64]); |
136 { | 158 { |
137 // Create the bit length array for the full command alphabet. | 159 /* Create the bit length array for the full command alphabet. */ |
138 uint8_t cmd_depth[704] = { 0 }; | 160 size_t i; |
| 161 memset(cmd_depth, 0, 64); /* only 64 first values were used */ |
139 memcpy(cmd_depth, depth, 8); | 162 memcpy(cmd_depth, depth, 8); |
140 memcpy(cmd_depth + 64, depth + 8, 8); | 163 memcpy(cmd_depth + 64, depth + 8, 8); |
141 memcpy(cmd_depth + 128, depth + 16, 8); | 164 memcpy(cmd_depth + 128, depth + 16, 8); |
142 memcpy(cmd_depth + 192, depth + 24, 8); | 165 memcpy(cmd_depth + 192, depth + 24, 8); |
143 memcpy(cmd_depth + 384, depth + 32, 8); | 166 memcpy(cmd_depth + 384, depth + 32, 8); |
144 for (size_t i = 0; i < 8; ++i) { | 167 for (i = 0; i < 8; ++i) { |
145 cmd_depth[128 + 8 * i] = depth[40 + i]; | 168 cmd_depth[128 + 8 * i] = depth[40 + i]; |
146 cmd_depth[256 + 8 * i] = depth[48 + i]; | 169 cmd_depth[256 + 8 * i] = depth[48 + i]; |
147 cmd_depth[448 + 8 * i] = depth[56 + i]; | 170 cmd_depth[448 + 8 * i] = depth[56 + i]; |
148 } | 171 } |
149 StoreHuffmanTree(cmd_depth, 704, tree, storage_ix, storage); | 172 BrotliStoreHuffmanTree( |
150 } | 173 cmd_depth, BROTLI_NUM_COMMAND_SYMBOLS, tree, storage_ix, storage); |
151 StoreHuffmanTree(&depth[64], 64, tree, storage_ix, storage); | 174 } |
152 } | 175 BrotliStoreHuffmanTree(&depth[64], 64, tree, storage_ix, storage); |
153 | 176 } |
154 // REQUIRES: insertlen < 6210 | 177 |
155 inline void EmitInsertLen(size_t insertlen, | 178 /* REQUIRES: insertlen < 6210 */ |
156 const uint8_t depth[128], | 179 static BROTLI_INLINE void EmitInsertLen(size_t insertlen, |
157 const uint16_t bits[128], | 180 const uint8_t depth[128], |
158 uint32_t histo[128], | 181 const uint16_t bits[128], |
159 size_t* storage_ix, | 182 uint32_t histo[128], |
160 uint8_t* storage) { | 183 size_t* storage_ix, |
| 184 uint8_t* storage) { |
161 if (insertlen < 6) { | 185 if (insertlen < 6) { |
162 const size_t code = insertlen + 40; | 186 const size_t code = insertlen + 40; |
163 WriteBits(depth[code], bits[code], storage_ix, storage); | 187 BrotliWriteBits(depth[code], bits[code], storage_ix, storage); |
164 ++histo[code]; | 188 ++histo[code]; |
165 } else if (insertlen < 130) { | 189 } else if (insertlen < 130) { |
166 insertlen -= 2; | 190 const size_t tail = insertlen - 2; |
167 const uint32_t nbits = Log2FloorNonZero(insertlen) - 1u; | 191 const uint32_t nbits = Log2FloorNonZero(tail) - 1u; |
168 const size_t prefix = insertlen >> nbits; | 192 const size_t prefix = tail >> nbits; |
169 const size_t inscode = (nbits << 1) + prefix + 42; | 193 const size_t inscode = (nbits << 1) + prefix + 42; |
170 WriteBits(depth[inscode], bits[inscode], storage_ix, storage); | 194 BrotliWriteBits(depth[inscode], bits[inscode], storage_ix, storage); |
171 WriteBits(nbits, insertlen - (prefix << nbits), storage_ix, storage); | 195 BrotliWriteBits(nbits, tail - (prefix << nbits), storage_ix, storage); |
172 ++histo[inscode]; | 196 ++histo[inscode]; |
173 } else if (insertlen < 2114) { | 197 } else if (insertlen < 2114) { |
174 insertlen -= 66; | 198 const size_t tail = insertlen - 66; |
175 const uint32_t nbits = Log2FloorNonZero(insertlen); | 199 const uint32_t nbits = Log2FloorNonZero(tail); |
176 const size_t code = nbits + 50; | 200 const size_t code = nbits + 50; |
177 WriteBits(depth[code], bits[code], storage_ix, storage); | 201 BrotliWriteBits(depth[code], bits[code], storage_ix, storage); |
178 WriteBits(nbits, insertlen - (1 << nbits), storage_ix, storage); | 202 BrotliWriteBits(nbits, tail - ((size_t)1 << nbits), storage_ix, storage); |
179 ++histo[code]; | 203 ++histo[code]; |
180 } else { | 204 } else { |
181 WriteBits(depth[61], bits[61], storage_ix, storage); | 205 BrotliWriteBits(depth[61], bits[61], storage_ix, storage); |
182 WriteBits(12, insertlen - 2114, storage_ix, storage); | 206 BrotliWriteBits(12, insertlen - 2114, storage_ix, storage); |
183 ++histo[21]; | 207 ++histo[21]; |
184 } | 208 } |
185 } | 209 } |
186 | 210 |
187 inline void EmitLongInsertLen(size_t insertlen, | 211 static BROTLI_INLINE void EmitLongInsertLen(size_t insertlen, |
188 const uint8_t depth[128], | 212 const uint8_t depth[128], |
189 const uint16_t bits[128], | 213 const uint16_t bits[128], |
190 uint32_t histo[128], | 214 uint32_t histo[128], |
191 size_t* storage_ix, | 215 size_t* storage_ix, |
192 uint8_t* storage) { | 216 uint8_t* storage) { |
193 if (insertlen < 22594) { | 217 if (insertlen < 22594) { |
194 WriteBits(depth[62], bits[62], storage_ix, storage); | 218 BrotliWriteBits(depth[62], bits[62], storage_ix, storage); |
195 WriteBits(14, insertlen - 6210, storage_ix, storage); | 219 BrotliWriteBits(14, insertlen - 6210, storage_ix, storage); |
196 ++histo[22]; | 220 ++histo[22]; |
197 } else { | 221 } else { |
198 WriteBits(depth[63], bits[63], storage_ix, storage); | 222 BrotliWriteBits(depth[63], bits[63], storage_ix, storage); |
199 WriteBits(24, insertlen - 22594, storage_ix, storage); | 223 BrotliWriteBits(24, insertlen - 22594, storage_ix, storage); |
200 ++histo[23]; | 224 ++histo[23]; |
201 } | 225 } |
202 } | 226 } |
203 | 227 |
204 inline void EmitCopyLen(size_t copylen, | 228 static BROTLI_INLINE void EmitCopyLen(size_t copylen, |
205 const uint8_t depth[128], | 229 const uint8_t depth[128], |
206 const uint16_t bits[128], | 230 const uint16_t bits[128], |
207 uint32_t histo[128], | 231 uint32_t histo[128], |
208 size_t* storage_ix, | 232 size_t* storage_ix, |
209 uint8_t* storage) { | 233 uint8_t* storage) { |
210 if (copylen < 10) { | 234 if (copylen < 10) { |
211 WriteBits(depth[copylen + 14], bits[copylen + 14], storage_ix, storage); | 235 BrotliWriteBits( |
| 236 depth[copylen + 14], bits[copylen + 14], storage_ix, storage); |
212 ++histo[copylen + 14]; | 237 ++histo[copylen + 14]; |
213 } else if (copylen < 134) { | 238 } else if (copylen < 134) { |
214 copylen -= 6; | 239 const size_t tail = copylen - 6; |
215 const uint32_t nbits = Log2FloorNonZero(copylen) - 1u; | 240 const uint32_t nbits = Log2FloorNonZero(tail) - 1u; |
216 const size_t prefix = copylen >> nbits; | 241 const size_t prefix = tail >> nbits; |
217 const size_t code = (nbits << 1) + prefix + 20; | 242 const size_t code = (nbits << 1) + prefix + 20; |
218 WriteBits(depth[code], bits[code], storage_ix, storage); | 243 BrotliWriteBits(depth[code], bits[code], storage_ix, storage); |
219 WriteBits(nbits, copylen - (prefix << nbits), storage_ix, storage); | 244 BrotliWriteBits(nbits, tail - (prefix << nbits), storage_ix, storage); |
220 ++histo[code]; | 245 ++histo[code]; |
221 } else if (copylen < 2118) { | 246 } else if (copylen < 2118) { |
222 copylen -= 70; | 247 const size_t tail = copylen - 70; |
223 const uint32_t nbits = Log2FloorNonZero(copylen); | 248 const uint32_t nbits = Log2FloorNonZero(tail); |
224 const size_t code = nbits + 28; | 249 const size_t code = nbits + 28; |
225 WriteBits(depth[code], bits[code], storage_ix, storage); | 250 BrotliWriteBits(depth[code], bits[code], storage_ix, storage); |
226 WriteBits(nbits, copylen - (1 << nbits), storage_ix, storage); | 251 BrotliWriteBits(nbits, tail - ((size_t)1 << nbits), storage_ix, storage); |
227 ++histo[code]; | 252 ++histo[code]; |
228 } else { | 253 } else { |
229 WriteBits(depth[39], bits[39], storage_ix, storage); | 254 BrotliWriteBits(depth[39], bits[39], storage_ix, storage); |
230 WriteBits(24, copylen - 2118, storage_ix, storage); | 255 BrotliWriteBits(24, copylen - 2118, storage_ix, storage); |
231 ++histo[47]; | 256 ++histo[47]; |
232 } | 257 } |
233 } | 258 } |
234 | 259 |
235 inline void EmitCopyLenLastDistance(size_t copylen, | 260 static BROTLI_INLINE void EmitCopyLenLastDistance(size_t copylen, |
236 const uint8_t depth[128], | 261 const uint8_t depth[128], |
237 const uint16_t bits[128], | 262 const uint16_t bits[128], |
238 uint32_t histo[128], | 263 uint32_t histo[128], |
239 size_t* storage_ix, | 264 size_t* storage_ix, |
240 uint8_t* storage) { | 265 uint8_t* storage) { |
241 if (copylen < 12) { | 266 if (copylen < 12) { |
242 WriteBits(depth[copylen - 4], bits[copylen - 4], storage_ix, storage); | 267 BrotliWriteBits(depth[copylen - 4], bits[copylen - 4], storage_ix, storage); |
243 ++histo[copylen - 4]; | 268 ++histo[copylen - 4]; |
244 } else if (copylen < 72) { | 269 } else if (copylen < 72) { |
245 copylen -= 8; | 270 const size_t tail = copylen - 8; |
246 const uint32_t nbits = Log2FloorNonZero(copylen) - 1; | 271 const uint32_t nbits = Log2FloorNonZero(tail) - 1; |
247 const size_t prefix = copylen >> nbits; | 272 const size_t prefix = tail >> nbits; |
248 const size_t code = (nbits << 1) + prefix + 4; | 273 const size_t code = (nbits << 1) + prefix + 4; |
249 WriteBits(depth[code], bits[code], storage_ix, storage); | 274 BrotliWriteBits(depth[code], bits[code], storage_ix, storage); |
250 WriteBits(nbits, copylen - (prefix << nbits), storage_ix, storage); | 275 BrotliWriteBits(nbits, tail - (prefix << nbits), storage_ix, storage); |
251 ++histo[code]; | 276 ++histo[code]; |
252 } else if (copylen < 136) { | 277 } else if (copylen < 136) { |
253 copylen -= 8; | 278 const size_t tail = copylen - 8; |
254 const size_t code = (copylen >> 5) + 30; | 279 const size_t code = (tail >> 5) + 30; |
255 WriteBits(depth[code], bits[code], storage_ix, storage); | 280 BrotliWriteBits(depth[code], bits[code], storage_ix, storage); |
256 WriteBits(5, copylen & 31, storage_ix, storage); | 281 BrotliWriteBits(5, tail & 31, storage_ix, storage); |
257 WriteBits(depth[64], bits[64], storage_ix, storage); | 282 BrotliWriteBits(depth[64], bits[64], storage_ix, storage); |
258 ++histo[code]; | 283 ++histo[code]; |
259 ++histo[64]; | 284 ++histo[64]; |
260 } else if (copylen < 2120) { | 285 } else if (copylen < 2120) { |
261 copylen -= 72; | 286 const size_t tail = copylen - 72; |
262 const uint32_t nbits = Log2FloorNonZero(copylen); | 287 const uint32_t nbits = Log2FloorNonZero(tail); |
263 const size_t code = nbits + 28; | 288 const size_t code = nbits + 28; |
264 WriteBits(depth[code], bits[code], storage_ix, storage); | 289 BrotliWriteBits(depth[code], bits[code], storage_ix, storage); |
265 WriteBits(nbits, copylen - (1 << nbits), storage_ix, storage); | 290 BrotliWriteBits(nbits, tail - ((size_t)1 << nbits), storage_ix, storage); |
266 WriteBits(depth[64], bits[64], storage_ix, storage); | 291 BrotliWriteBits(depth[64], bits[64], storage_ix, storage); |
267 ++histo[code]; | 292 ++histo[code]; |
268 ++histo[64]; | 293 ++histo[64]; |
269 } else { | 294 } else { |
270 WriteBits(depth[39], bits[39], storage_ix, storage); | 295 BrotliWriteBits(depth[39], bits[39], storage_ix, storage); |
271 WriteBits(24, copylen - 2120, storage_ix, storage); | 296 BrotliWriteBits(24, copylen - 2120, storage_ix, storage); |
272 WriteBits(depth[64], bits[64], storage_ix, storage); | 297 BrotliWriteBits(depth[64], bits[64], storage_ix, storage); |
273 ++histo[47]; | 298 ++histo[47]; |
274 ++histo[64]; | 299 ++histo[64]; |
275 } | 300 } |
276 } | 301 } |
277 | 302 |
278 inline void EmitDistance(size_t distance, | 303 static BROTLI_INLINE void EmitDistance(size_t distance, |
279 const uint8_t depth[128], | 304 const uint8_t depth[128], |
280 const uint16_t bits[128], | 305 const uint16_t bits[128], |
281 uint32_t histo[128], | 306 uint32_t histo[128], |
282 size_t* storage_ix, uint8_t* storage) { | 307 size_t* storage_ix, uint8_t* storage) { |
283 distance += 3; | 308 const size_t d = distance + 3; |
284 const uint32_t nbits = Log2FloorNonZero(distance) - 1u; | 309 const uint32_t nbits = Log2FloorNonZero(d) - 1u; |
285 const size_t prefix = (distance >> nbits) & 1; | 310 const size_t prefix = (d >> nbits) & 1; |
286 const size_t offset = (2 + prefix) << nbits; | 311 const size_t offset = (2 + prefix) << nbits; |
287 const size_t distcode = 2 * (nbits - 1) + prefix + 80; | 312 const size_t distcode = 2 * (nbits - 1) + prefix + 80; |
288 WriteBits(depth[distcode], bits[distcode], storage_ix, storage); | 313 BrotliWriteBits(depth[distcode], bits[distcode], storage_ix, storage); |
289 WriteBits(nbits, distance - offset, storage_ix, storage); | 314 BrotliWriteBits(nbits, d - offset, storage_ix, storage); |
290 ++histo[distcode]; | 315 ++histo[distcode]; |
291 } | 316 } |
292 | 317 |
293 inline void EmitLiterals(const uint8_t* input, const size_t len, | 318 static BROTLI_INLINE void EmitLiterals(const uint8_t* input, const size_t len, |
294 const uint8_t depth[256], const uint16_t bits[256], | 319 const uint8_t depth[256], |
295 size_t* storage_ix, uint8_t* storage) { | 320 const uint16_t bits[256], |
296 for (size_t j = 0; j < len; j++) { | 321 size_t* storage_ix, uint8_t* storage) { |
| 322 size_t j; |
| 323 for (j = 0; j < len; j++) { |
297 const uint8_t lit = input[j]; | 324 const uint8_t lit = input[j]; |
298 WriteBits(depth[lit], bits[lit], storage_ix, storage); | 325 BrotliWriteBits(depth[lit], bits[lit], storage_ix, storage); |
299 } | 326 } |
300 } | 327 } |
301 | 328 |
302 // REQUIRES: len <= 1 << 20. | 329 /* REQUIRES: len <= 1 << 20. */ |
303 static void StoreMetaBlockHeader( | 330 static void BrotliStoreMetaBlockHeader( |
304 size_t len, bool is_uncompressed, size_t* storage_ix, uint8_t* storage) { | 331 size_t len, BROTLI_BOOL is_uncompressed, size_t* storage_ix, |
305 // ISLAST | 332 uint8_t* storage) { |
306 WriteBits(1, 0, storage_ix, storage); | 333 /* ISLAST */ |
| 334 BrotliWriteBits(1, 0, storage_ix, storage); |
307 if (len <= (1U << 16)) { | 335 if (len <= (1U << 16)) { |
308 // MNIBBLES is 4 | 336 /* MNIBBLES is 4 */ |
309 WriteBits(2, 0, storage_ix, storage); | 337 BrotliWriteBits(2, 0, storage_ix, storage); |
310 WriteBits(16, len - 1, storage_ix, storage); | 338 BrotliWriteBits(16, len - 1, storage_ix, storage); |
311 } else { | 339 } else { |
312 // MNIBBLES is 5 | 340 /* MNIBBLES is 5 */ |
313 WriteBits(2, 1, storage_ix, storage); | 341 BrotliWriteBits(2, 1, storage_ix, storage); |
314 WriteBits(20, len - 1, storage_ix, storage); | 342 BrotliWriteBits(20, len - 1, storage_ix, storage); |
315 } | 343 } |
316 // ISUNCOMPRESSED | 344 /* ISUNCOMPRESSED */ |
317 WriteBits(1, is_uncompressed, storage_ix, storage); | 345 BrotliWriteBits(1, (uint64_t)is_uncompressed, storage_ix, storage); |
318 } | 346 } |
319 | 347 |
320 static void UpdateBits(size_t n_bits, | 348 static void UpdateBits(size_t n_bits, uint32_t bits, size_t pos, |
321 uint32_t bits, | 349 uint8_t *array) { |
322 size_t pos, | |
323 uint8_t *array) { | |
324 while (n_bits > 0) { | 350 while (n_bits > 0) { |
325 size_t byte_pos = pos >> 3; | 351 size_t byte_pos = pos >> 3; |
326 size_t n_unchanged_bits = pos & 7; | 352 size_t n_unchanged_bits = pos & 7; |
327 size_t n_changed_bits = std::min(n_bits, 8 - n_unchanged_bits); | 353 size_t n_changed_bits = BROTLI_MIN(size_t, n_bits, 8 - n_unchanged_bits); |
328 size_t total_bits = n_unchanged_bits + n_changed_bits; | 354 size_t total_bits = n_unchanged_bits + n_changed_bits; |
329 uint32_t mask = (~((1 << total_bits) - 1)) | ((1 << n_unchanged_bits) - 1); | 355 uint32_t mask = |
| 356 (~((1u << total_bits) - 1u)) | ((1u << n_unchanged_bits) - 1u); |
330 uint32_t unchanged_bits = array[byte_pos] & mask; | 357 uint32_t unchanged_bits = array[byte_pos] & mask; |
331 uint32_t changed_bits = bits & ((1 << n_changed_bits) - 1); | 358 uint32_t changed_bits = bits & ((1u << n_changed_bits) - 1u); |
332 array[byte_pos] = | 359 array[byte_pos] = |
333 static_cast<uint8_t>((changed_bits << n_unchanged_bits) | | 360 (uint8_t)((changed_bits << n_unchanged_bits) | unchanged_bits); |
334 unchanged_bits); | |
335 n_bits -= n_changed_bits; | 361 n_bits -= n_changed_bits; |
336 bits >>= n_changed_bits; | 362 bits >>= n_changed_bits; |
337 pos += n_changed_bits; | 363 pos += n_changed_bits; |
338 } | 364 } |
339 } | 365 } |
340 | 366 |
341 static void RewindBitPosition(const size_t new_storage_ix, | 367 static void RewindBitPosition(const size_t new_storage_ix, |
342 size_t* storage_ix, uint8_t* storage) { | 368 size_t* storage_ix, uint8_t* storage) { |
343 const size_t bitpos = new_storage_ix & 7; | 369 const size_t bitpos = new_storage_ix & 7; |
344 const size_t mask = (1u << bitpos) - 1; | 370 const size_t mask = (1u << bitpos) - 1; |
345 storage[new_storage_ix >> 3] &= static_cast<uint8_t>(mask); | 371 storage[new_storage_ix >> 3] &= (uint8_t)mask; |
346 *storage_ix = new_storage_ix; | 372 *storage_ix = new_storage_ix; |
347 } | 373 } |
348 | 374 |
349 static bool ShouldMergeBlock(const uint8_t* data, size_t len, | 375 static BROTLI_BOOL ShouldMergeBlock( |
350 const uint8_t* depths) { | 376 const uint8_t* data, size_t len, const uint8_t* depths) { |
351 size_t histo[256] = { 0 }; | 377 size_t histo[256] = { 0 }; |
352 static const size_t kSampleRate = 43; | 378 static const size_t kSampleRate = 43; |
353 for (size_t i = 0; i < len; i += kSampleRate) { | 379 size_t i; |
| 380 for (i = 0; i < len; i += kSampleRate) { |
354 ++histo[data[i]]; | 381 ++histo[data[i]]; |
355 } | 382 } |
356 const size_t total = (len + kSampleRate - 1) / kSampleRate; | 383 { |
357 double r = (FastLog2(total) + 0.5) * static_cast<double>(total) + 200; | 384 const size_t total = (len + kSampleRate - 1) / kSampleRate; |
358 for (size_t i = 0; i < 256; ++i) { | 385 double r = (FastLog2(total) + 0.5) * (double)total + 200; |
359 r -= static_cast<double>(histo[i]) * (depths[i] + FastLog2(histo[i])); | 386 for (i = 0; i < 256; ++i) { |
| 387 r -= (double)histo[i] * (depths[i] + FastLog2(histo[i])); |
| 388 } |
| 389 return TO_BROTLI_BOOL(r >= 0.0); |
360 } | 390 } |
361 return r >= 0.0; | |
362 } | 391 } |
363 | 392 |
364 inline bool ShouldUseUncompressedMode(const uint8_t* metablock_start, | 393 /* Acceptable loss for uncompressible speedup is 2% */ |
365 const uint8_t* next_emit, | 394 #define MIN_RATIO 980 |
366 const size_t insertlen, | 395 |
367 const uint8_t literal_depths[256]) { | 396 static BROTLI_INLINE BROTLI_BOOL ShouldUseUncompressedMode( |
368 const size_t compressed = static_cast<size_t>(next_emit - metablock_start); | 397 const uint8_t* metablock_start, const uint8_t* next_emit, |
| 398 const size_t insertlen, const size_t literal_ratio) { |
| 399 const size_t compressed = (size_t)(next_emit - metablock_start); |
369 if (compressed * 50 > insertlen) { | 400 if (compressed * 50 > insertlen) { |
370 return false; | 401 return BROTLI_FALSE; |
| 402 } else { |
| 403 return TO_BROTLI_BOOL(literal_ratio > MIN_RATIO); |
371 } | 404 } |
372 static const double kAcceptableLossForUncompressibleSpeedup = 0.02; | |
373 static const double kMinEntropy = | |
374 8 * (1.0 - kAcceptableLossForUncompressibleSpeedup); | |
375 uint32_t sum = 0; | |
376 for (int i = 0; i < 256; ++i) { | |
377 const uint32_t n = literal_depths[i]; | |
378 sum += n << (15 - n); | |
379 } | |
380 return sum > static_cast<uint32_t>((1 << 15) * kMinEntropy); | |
381 } | 405 } |
382 | 406 |
383 static void EmitUncompressedMetaBlock(const uint8_t* begin, const uint8_t* end, | 407 static void EmitUncompressedMetaBlock(const uint8_t* begin, const uint8_t* end, |
384 const size_t storage_ix_start, | 408 const size_t storage_ix_start, |
385 size_t* storage_ix, uint8_t* storage) { | 409 size_t* storage_ix, uint8_t* storage) { |
386 const size_t len = static_cast<size_t>(end - begin); | 410 const size_t len = (size_t)(end - begin); |
387 RewindBitPosition(storage_ix_start, storage_ix, storage); | 411 RewindBitPosition(storage_ix_start, storage_ix, storage); |
388 StoreMetaBlockHeader(len, 1, storage_ix, storage); | 412 BrotliStoreMetaBlockHeader(len, 1, storage_ix, storage); |
389 *storage_ix = (*storage_ix + 7u) & ~7u; | 413 *storage_ix = (*storage_ix + 7u) & ~7u; |
390 memcpy(&storage[*storage_ix >> 3], begin, len); | 414 memcpy(&storage[*storage_ix >> 3], begin, len); |
391 *storage_ix += len << 3; | 415 *storage_ix += len << 3; |
392 storage[*storage_ix >> 3] = 0; | 416 storage[*storage_ix >> 3] = 0; |
393 } | 417 } |
394 | 418 |
395 void BrotliCompressFragmentFast(const uint8_t* input, size_t input_size, | 419 static uint32_t kCmdHistoSeed[128] = { |
396 bool is_last, | 420 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, |
397 int* table, size_t table_size, | 421 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, |
398 uint8_t cmd_depth[128], uint16_t cmd_bits[128], | 422 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, |
399 size_t* cmd_code_numbits, uint8_t* cmd_code, | 423 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, |
400 size_t* storage_ix, uint8_t* storage) { | 424 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, |
401 if (input_size == 0) { | 425 1, 1, 1, 1, 0, 0, 0, 0, |
402 assert(is_last); | 426 }; |
403 WriteBits(1, 1, storage_ix, storage); // islast | |
404 WriteBits(1, 1, storage_ix, storage); // isempty | |
405 *storage_ix = (*storage_ix + 7u) & ~7u; | |
406 return; | |
407 } | |
408 | 427 |
409 // "next_emit" is a pointer to the first byte that is not covered by a | 428 static BROTLI_INLINE void BrotliCompressFragmentFastImpl( |
410 // previous copy. Bytes between "next_emit" and the start of the next copy or | 429 MemoryManager* m, const uint8_t* input, size_t input_size, |
411 // the end of the input will be emitted as literal bytes. | 430 BROTLI_BOOL is_last, int* table, size_t table_bits, uint8_t cmd_depth[128], |
| 431 uint16_t cmd_bits[128], size_t* cmd_code_numbits, uint8_t* cmd_code, |
| 432 size_t* storage_ix, uint8_t* storage) { |
| 433 uint32_t cmd_histo[128]; |
| 434 const uint8_t* ip_end; |
| 435 |
| 436 /* "next_emit" is a pointer to the first byte that is not covered by a |
| 437 previous copy. Bytes between "next_emit" and the start of the next copy or |
| 438 the end of the input will be emitted as literal bytes. */ |
412 const uint8_t* next_emit = input; | 439 const uint8_t* next_emit = input; |
413 // Save the start of the first block for position and distance computations. | 440 /* Save the start of the first block for position and distance computations. |
| 441 */ |
414 const uint8_t* base_ip = input; | 442 const uint8_t* base_ip = input; |
415 | 443 |
416 static const size_t kFirstBlockSize = 3 << 15; | 444 static const size_t kFirstBlockSize = 3 << 15; |
417 static const size_t kMergeBlockSize = 1 << 16; | 445 static const size_t kMergeBlockSize = 1 << 16; |
418 | 446 |
| 447 const size_t kInputMarginBytes = BROTLI_WINDOW_GAP; |
| 448 const size_t kMinMatchLen = 5; |
| 449 |
419 const uint8_t* metablock_start = input; | 450 const uint8_t* metablock_start = input; |
420 size_t block_size = std::min(input_size, kFirstBlockSize); | 451 size_t block_size = BROTLI_MIN(size_t, input_size, kFirstBlockSize); |
421 size_t total_block_size = block_size; | 452 size_t total_block_size = block_size; |
422 // Save the bit position of the MLEN field of the meta-block header, so that | 453 /* Save the bit position of the MLEN field of the meta-block header, so that |
423 // we can update it later if we decide to extend this meta-block. | 454 we can update it later if we decide to extend this meta-block. */ |
424 size_t mlen_storage_ix = *storage_ix + 3; | 455 size_t mlen_storage_ix = *storage_ix + 3; |
425 StoreMetaBlockHeader(block_size, 0, storage_ix, storage); | |
426 // No block splits, no contexts. | |
427 WriteBits(13, 0, storage_ix, storage); | |
428 | 456 |
429 uint8_t lit_depth[256] = { 0 }; | 457 uint8_t lit_depth[256]; |
430 uint16_t lit_bits[256] = { 0 }; | 458 uint16_t lit_bits[256]; |
431 BuildAndStoreLiteralPrefixCode(input, block_size, lit_depth, lit_bits, | |
432 storage_ix, storage); | |
433 | 459 |
434 // Store the pre-compressed command and distance prefix codes. | 460 size_t literal_ratio; |
435 for (size_t i = 0; i + 7 < *cmd_code_numbits; i += 8) { | 461 |
436 WriteBits(8, cmd_code[i >> 3], storage_ix, storage); | 462 const uint8_t* ip; |
| 463 int last_distance; |
| 464 |
| 465 const size_t shift = 64u - table_bits; |
| 466 |
| 467 if (input_size == 0) { |
| 468 assert(is_last); |
| 469 BrotliWriteBits(1, 1, storage_ix, storage); /* islast */ |
| 470 BrotliWriteBits(1, 1, storage_ix, storage); /* isempty */ |
| 471 *storage_ix = (*storage_ix + 7u) & ~7u; |
| 472 return; |
437 } | 473 } |
438 WriteBits(*cmd_code_numbits & 7, cmd_code[*cmd_code_numbits >> 3], | 474 |
439 storage_ix, storage); | 475 BrotliStoreMetaBlockHeader(block_size, 0, storage_ix, storage); |
| 476 /* No block splits, no contexts. */ |
| 477 BrotliWriteBits(13, 0, storage_ix, storage); |
| 478 |
| 479 literal_ratio = BuildAndStoreLiteralPrefixCode( |
| 480 m, input, block_size, lit_depth, lit_bits, storage_ix, storage); |
| 481 if (BROTLI_IS_OOM(m)) return; |
| 482 |
| 483 { |
| 484 /* Store the pre-compressed command and distance prefix codes. */ |
| 485 size_t i; |
| 486 for (i = 0; i + 7 < *cmd_code_numbits; i += 8) { |
| 487 BrotliWriteBits(8, cmd_code[i >> 3], storage_ix, storage); |
| 488 } |
| 489 } |
| 490 BrotliWriteBits(*cmd_code_numbits & 7, cmd_code[*cmd_code_numbits >> 3], |
| 491 storage_ix, storage); |
440 | 492 |
441 emit_commands: | 493 emit_commands: |
442 // Initialize the command and distance histograms. We will gather | 494 /* Initialize the command and distance histograms. We will gather |
443 // statistics of command and distance codes during the processing | 495 statistics of command and distance codes during the processing |
444 // of this block and use it to update the command and distance | 496 of this block and use it to update the command and distance |
445 // prefix codes for the next block. | 497 prefix codes for the next block. */ |
446 uint32_t cmd_histo[128] = { | 498 memcpy(cmd_histo, kCmdHistoSeed, sizeof(kCmdHistoSeed)); |
447 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, | |
448 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, | |
449 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, | |
450 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, | |
451 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, | |
452 1, 1, 1, 1, 0, 0, 0, 0, | |
453 }; | |
454 | 499 |
455 // "ip" is the input pointer. | 500 /* "ip" is the input pointer. */ |
456 const uint8_t* ip = input; | 501 ip = input; |
457 assert(table_size); | 502 last_distance = -1; |
458 assert(table_size <= (1u << 31)); | 503 ip_end = input + block_size; |
459 assert((table_size & (table_size - 1)) == 0); // table must be power of two | |
460 const size_t shift = 64u - Log2FloorNonZero(table_size); | |
461 assert(table_size - 1 == static_cast<size_t>( | |
462 MAKE_UINT64_T(0xFFFFFFFF, 0xFFFFFF) >> shift)); | |
463 const uint8_t* ip_end = input + block_size; | |
464 | 504 |
465 int last_distance = -1; | 505 if (BROTLI_PREDICT_TRUE(block_size >= kInputMarginBytes)) { |
466 const size_t kInputMarginBytes = 16; | 506 /* For the last block, we need to keep a 16 bytes margin so that we can be |
467 const size_t kMinMatchLen = 5; | 507 sure that all distances are at most window size - 16. |
468 if (PREDICT_TRUE(block_size >= kInputMarginBytes)) { | 508 For all other blocks, we only need to keep a margin of 5 bytes so that |
469 // For the last block, we need to keep a 16 bytes margin so that we can be | 509 we don't go over the block size with a copy. */ |
470 // sure that all distances are at most window size - 16. | 510 const size_t len_limit = BROTLI_MIN(size_t, block_size - kMinMatchLen, |
471 // For all other blocks, we only need to keep a margin of 5 bytes so that | 511 input_size - kInputMarginBytes); |
472 // we don't go over the block size with a copy. | |
473 const size_t len_limit = std::min(block_size - kMinMatchLen, | |
474 input_size - kInputMarginBytes); | |
475 const uint8_t* ip_limit = input + len_limit; | 512 const uint8_t* ip_limit = input + len_limit; |
476 | 513 |
477 for (uint32_t next_hash = Hash(++ip, shift); ; ) { | 514 uint32_t next_hash; |
478 assert(next_emit < ip); | 515 for (next_hash = Hash(++ip, shift); ; ) { |
479 // Step 1: Scan forward in the input looking for a 5-byte-long match. | 516 /* Step 1: Scan forward in the input looking for a 5-byte-long match. |
480 // If we get close to exhausting the input then goto emit_remainder. | 517 If we get close to exhausting the input then goto emit_remainder. |
481 // | 518 |
482 // Heuristic match skipping: If 32 bytes are scanned with no matches | 519 Heuristic match skipping: If 32 bytes are scanned with no matches |
483 // found, start looking only at every other byte. If 32 more bytes are | 520 found, start looking only at every other byte. If 32 more bytes are |
484 // scanned, look at every third byte, etc.. When a match is found, | 521 scanned, look at every third byte, etc.. When a match is found, |
485 // immediately go back to looking at every byte. This is a small loss | 522 immediately go back to looking at every byte. This is a small loss |
486 // (~5% performance, ~0.1% density) for compressible data due to more | 523 (~5% performance, ~0.1% density) for compressible data due to more |
487 // bookkeeping, but for non-compressible data (such as JPEG) it's a huge | 524 bookkeeping, but for non-compressible data (such as JPEG) it's a huge |
488 // win since the compressor quickly "realizes" the data is incompressible | 525 win since the compressor quickly "realizes" the data is incompressible |
489 // and doesn't bother looking for matches everywhere. | 526 and doesn't bother looking for matches everywhere. |
490 // | 527 |
491 // The "skip" variable keeps track of how many bytes there are since the | 528 The "skip" variable keeps track of how many bytes there are since the |
492 // last match; dividing it by 32 (ie. right-shifting by five) gives the | 529 last match; dividing it by 32 (i.e. right-shifting by five) gives the |
493 // number of bytes to move ahead for each iteration. | 530 number of bytes to move ahead for each iteration. */ |
494 uint32_t skip = 32; | 531 uint32_t skip = 32; |
495 | 532 |
496 const uint8_t* next_ip = ip; | 533 const uint8_t* next_ip = ip; |
497 const uint8_t* candidate; | 534 const uint8_t* candidate; |
| 535 assert(next_emit < ip); |
| 536 trawl: |
498 do { | 537 do { |
| 538 uint32_t hash = next_hash; |
| 539 uint32_t bytes_between_hash_lookups = skip++ >> 5; |
| 540 assert(hash == Hash(next_ip, shift)); |
499 ip = next_ip; | 541 ip = next_ip; |
500 uint32_t hash = next_hash; | |
501 assert(hash == Hash(ip, shift)); | |
502 uint32_t bytes_between_hash_lookups = skip++ >> 5; | |
503 next_ip = ip + bytes_between_hash_lookups; | 542 next_ip = ip + bytes_between_hash_lookups; |
504 if (PREDICT_FALSE(next_ip > ip_limit)) { | 543 if (BROTLI_PREDICT_FALSE(next_ip > ip_limit)) { |
505 goto emit_remainder; | 544 goto emit_remainder; |
506 } | 545 } |
507 next_hash = Hash(next_ip, shift); | 546 next_hash = Hash(next_ip, shift); |
508 candidate = ip - last_distance; | 547 candidate = ip - last_distance; |
509 if (IsMatch(ip, candidate)) { | 548 if (IsMatch(ip, candidate)) { |
510 if (PREDICT_TRUE(candidate < ip)) { | 549 if (BROTLI_PREDICT_TRUE(candidate < ip)) { |
511 table[hash] = static_cast<int>(ip - base_ip); | 550 table[hash] = (int)(ip - base_ip); |
512 break; | 551 break; |
513 } | 552 } |
514 } | 553 } |
515 candidate = base_ip + table[hash]; | 554 candidate = base_ip + table[hash]; |
516 assert(candidate >= base_ip); | 555 assert(candidate >= base_ip); |
517 assert(candidate < ip); | 556 assert(candidate < ip); |
518 | 557 |
519 table[hash] = static_cast<int>(ip - base_ip); | 558 table[hash] = (int)(ip - base_ip); |
520 } while (PREDICT_TRUE(!IsMatch(ip, candidate))); | 559 } while (BROTLI_PREDICT_TRUE(!IsMatch(ip, candidate))); |
521 | 560 |
522 // Step 2: Emit the found match together with the literal bytes from | 561 /* Check copy distance. If candidate is not feasible, continue search. |
523 // "next_emit" to the bit stream, and then see if we can find a next macth | 562 Checking is done outside of hot loop to reduce overhead. */ |
524 // immediately afterwards. Repeat until we find no match for the input | 563 if (ip - candidate > MAX_DISTANCE) goto trawl; |
525 // without emitting some literal bytes. | 564 |
526 uint64_t input_bytes; | 565 /* Step 2: Emit the found match together with the literal bytes from |
| 566 "next_emit" to the bit stream, and then see if we can find a next match |
| 567 immediately afterwards. Repeat until we find no match for the input |
| 568 without emitting some literal bytes. */ |
527 | 569 |
528 { | 570 { |
529 // We have a 5-byte match at ip, and we need to emit bytes in | 571 /* We have a 5-byte match at ip, and we need to emit bytes in |
530 // [next_emit, ip). | 572 [next_emit, ip). */ |
531 const uint8_t* base = ip; | 573 const uint8_t* base = ip; |
532 size_t matched = 5 + FindMatchLengthWithLimit( | 574 size_t matched = 5 + FindMatchLengthWithLimit( |
533 candidate + 5, ip + 5, static_cast<size_t>(ip_end - ip) - 5); | 575 candidate + 5, ip + 5, (size_t)(ip_end - ip) - 5); |
| 576 int distance = (int)(base - candidate); /* > 0 */ |
| 577 size_t insert = (size_t)(base - next_emit); |
534 ip += matched; | 578 ip += matched; |
535 int distance = static_cast<int>(base - candidate); /* > 0 */ | |
536 size_t insert = static_cast<size_t>(base - next_emit); | |
537 assert(0 == memcmp(base, candidate, matched)); | 579 assert(0 == memcmp(base, candidate, matched)); |
538 if (PREDICT_TRUE(insert < 6210)) { | 580 if (BROTLI_PREDICT_TRUE(insert < 6210)) { |
539 EmitInsertLen(insert, cmd_depth, cmd_bits, cmd_histo, | 581 EmitInsertLen(insert, cmd_depth, cmd_bits, cmd_histo, |
540 storage_ix, storage); | 582 storage_ix, storage); |
541 } else if (ShouldUseUncompressedMode(metablock_start, next_emit, insert, | 583 } else if (ShouldUseUncompressedMode(metablock_start, next_emit, insert, |
542 lit_depth)) { | 584 literal_ratio)) { |
543 EmitUncompressedMetaBlock(metablock_start, base, mlen_storage_ix - 3, | 585 EmitUncompressedMetaBlock(metablock_start, base, mlen_storage_ix - 3, |
544 storage_ix, storage); | 586 storage_ix, storage); |
545 input_size -= static_cast<size_t>(base - input); | 587 input_size -= (size_t)(base - input); |
546 input = base; | 588 input = base; |
547 next_emit = input; | 589 next_emit = input; |
548 goto next_block; | 590 goto next_block; |
549 } else { | 591 } else { |
550 EmitLongInsertLen(insert, cmd_depth, cmd_bits, cmd_histo, | 592 EmitLongInsertLen(insert, cmd_depth, cmd_bits, cmd_histo, |
551 storage_ix, storage); | 593 storage_ix, storage); |
552 } | 594 } |
553 EmitLiterals(next_emit, insert, lit_depth, lit_bits, | 595 EmitLiterals(next_emit, insert, lit_depth, lit_bits, |
554 storage_ix, storage); | 596 storage_ix, storage); |
555 if (distance == last_distance) { | 597 if (distance == last_distance) { |
556 WriteBits(cmd_depth[64], cmd_bits[64], storage_ix, storage); | 598 BrotliWriteBits(cmd_depth[64], cmd_bits[64], storage_ix, storage); |
557 ++cmd_histo[64]; | 599 ++cmd_histo[64]; |
558 } else { | 600 } else { |
559 EmitDistance(static_cast<size_t>(distance), cmd_depth, cmd_bits, | 601 EmitDistance((size_t)distance, cmd_depth, cmd_bits, |
560 cmd_histo, storage_ix, storage); | 602 cmd_histo, storage_ix, storage); |
561 last_distance = distance; | 603 last_distance = distance; |
562 } | 604 } |
563 EmitCopyLenLastDistance(matched, cmd_depth, cmd_bits, cmd_histo, | 605 EmitCopyLenLastDistance(matched, cmd_depth, cmd_bits, cmd_histo, |
564 storage_ix, storage); | 606 storage_ix, storage); |
565 | 607 |
566 next_emit = ip; | 608 next_emit = ip; |
567 if (PREDICT_FALSE(ip >= ip_limit)) { | 609 if (BROTLI_PREDICT_FALSE(ip >= ip_limit)) { |
568 goto emit_remainder; | 610 goto emit_remainder; |
569 } | 611 } |
570 // We could immediately start working at ip now, but to improve | 612 /* We could immediately start working at ip now, but to improve |
571 // compression we first update "table" with the hashes of some positions | 613 compression we first update "table" with the hashes of some positions |
572 // within the last copy. | 614 within the last copy. */ |
573 input_bytes = BROTLI_UNALIGNED_LOAD64(ip - 3); | 615 { |
574 uint32_t prev_hash = HashBytesAtOffset(input_bytes, 0, shift); | 616 uint64_t input_bytes = BROTLI_UNALIGNED_LOAD64(ip - 3); |
575 table[prev_hash] = static_cast<int>(ip - base_ip - 3); | 617 uint32_t prev_hash = HashBytesAtOffset(input_bytes, 0, shift); |
576 prev_hash = HashBytesAtOffset(input_bytes, 1, shift); | 618 uint32_t cur_hash = HashBytesAtOffset(input_bytes, 3, shift); |
577 table[prev_hash] = static_cast<int>(ip - base_ip - 2); | 619 table[prev_hash] = (int)(ip - base_ip - 3); |
578 prev_hash = HashBytesAtOffset(input_bytes, 2, shift); | 620 prev_hash = HashBytesAtOffset(input_bytes, 1, shift); |
579 table[prev_hash] = static_cast<int>(ip - base_ip - 1); | 621 table[prev_hash] = (int)(ip - base_ip - 2); |
| 622 prev_hash = HashBytesAtOffset(input_bytes, 2, shift); |
| 623 table[prev_hash] = (int)(ip - base_ip - 1); |
580 | 624 |
581 uint32_t cur_hash = HashBytesAtOffset(input_bytes, 3, shift); | 625 candidate = base_ip + table[cur_hash]; |
582 candidate = base_ip + table[cur_hash]; | 626 table[cur_hash] = (int)(ip - base_ip); |
583 table[cur_hash] = static_cast<int>(ip - base_ip); | 627 } |
584 } | 628 } |
585 | 629 |
586 while (IsMatch(ip, candidate)) { | 630 while (IsMatch(ip, candidate)) { |
587 // We have a 5-byte match at ip, and no need to emit any literal bytes | 631 /* We have a 5-byte match at ip, and no need to emit any literal bytes |
588 // prior to ip. | 632 prior to ip. */ |
589 const uint8_t* base = ip; | 633 const uint8_t* base = ip; |
590 size_t matched = 5 + FindMatchLengthWithLimit( | 634 size_t matched = 5 + FindMatchLengthWithLimit( |
591 candidate + 5, ip + 5, static_cast<size_t>(ip_end - ip) - 5); | 635 candidate + 5, ip + 5, (size_t)(ip_end - ip) - 5); |
| 636 if (ip - candidate > MAX_DISTANCE) break; |
592 ip += matched; | 637 ip += matched; |
593 last_distance = static_cast<int>(base - candidate); /* > 0 */ | 638 last_distance = (int)(base - candidate); /* > 0 */ |
594 assert(0 == memcmp(base, candidate, matched)); | 639 assert(0 == memcmp(base, candidate, matched)); |
595 EmitCopyLen(matched, cmd_depth, cmd_bits, cmd_histo, | 640 EmitCopyLen(matched, cmd_depth, cmd_bits, cmd_histo, |
596 storage_ix, storage); | 641 storage_ix, storage); |
597 EmitDistance(static_cast<size_t>(last_distance), cmd_depth, cmd_bits, | 642 EmitDistance((size_t)last_distance, cmd_depth, cmd_bits, |
598 cmd_histo, storage_ix, storage); | 643 cmd_histo, storage_ix, storage); |
599 | 644 |
600 next_emit = ip; | 645 next_emit = ip; |
601 if (PREDICT_FALSE(ip >= ip_limit)) { | 646 if (BROTLI_PREDICT_FALSE(ip >= ip_limit)) { |
602 goto emit_remainder; | 647 goto emit_remainder; |
603 } | 648 } |
604 // We could immediately start working at ip now, but to improve | 649 /* We could immediately start working at ip now, but to improve |
605 // compression we first update "table" with the hashes of some positions | 650 compression we first update "table" with the hashes of some positions |
606 // within the last copy. | 651 within the last copy. */ |
607 input_bytes = BROTLI_UNALIGNED_LOAD64(ip - 3); | 652 { |
608 uint32_t prev_hash = HashBytesAtOffset(input_bytes, 0, shift); | 653 uint64_t input_bytes = BROTLI_UNALIGNED_LOAD64(ip - 3); |
609 table[prev_hash] = static_cast<int>(ip - base_ip - 3); | 654 uint32_t prev_hash = HashBytesAtOffset(input_bytes, 0, shift); |
610 prev_hash = HashBytesAtOffset(input_bytes, 1, shift); | 655 uint32_t cur_hash = HashBytesAtOffset(input_bytes, 3, shift); |
611 table[prev_hash] = static_cast<int>(ip - base_ip - 2); | 656 table[prev_hash] = (int)(ip - base_ip - 3); |
612 prev_hash = HashBytesAtOffset(input_bytes, 2, shift); | 657 prev_hash = HashBytesAtOffset(input_bytes, 1, shift); |
613 table[prev_hash] = static_cast<int>(ip - base_ip - 1); | 658 table[prev_hash] = (int)(ip - base_ip - 2); |
| 659 prev_hash = HashBytesAtOffset(input_bytes, 2, shift); |
| 660 table[prev_hash] = (int)(ip - base_ip - 1); |
614 | 661 |
615 uint32_t cur_hash = HashBytesAtOffset(input_bytes, 3, shift); | 662 candidate = base_ip + table[cur_hash]; |
616 candidate = base_ip + table[cur_hash]; | 663 table[cur_hash] = (int)(ip - base_ip); |
617 table[cur_hash] = static_cast<int>(ip - base_ip); | 664 } |
618 } | 665 } |
619 | 666 |
620 next_hash = Hash(++ip, shift); | 667 next_hash = Hash(++ip, shift); |
621 } | 668 } |
622 } | 669 } |
623 | 670 |
624 emit_remainder: | 671 emit_remainder: |
625 assert(next_emit <= ip_end); | 672 assert(next_emit <= ip_end); |
626 input += block_size; | 673 input += block_size; |
627 input_size -= block_size; | 674 input_size -= block_size; |
628 block_size = std::min(input_size, kMergeBlockSize); | 675 block_size = BROTLI_MIN(size_t, input_size, kMergeBlockSize); |
629 | 676 |
630 // Decide if we want to continue this meta-block instead of emitting the | 677 /* Decide if we want to continue this meta-block instead of emitting the |
631 // last insert-only command. | 678 last insert-only command. */ |
632 if (input_size > 0 && | 679 if (input_size > 0 && |
633 total_block_size + block_size <= (1 << 20) && | 680 total_block_size + block_size <= (1 << 20) && |
634 ShouldMergeBlock(input, block_size, lit_depth)) { | 681 ShouldMergeBlock(input, block_size, lit_depth)) { |
635 assert(total_block_size > (1 << 16)); | 682 assert(total_block_size > (1 << 16)); |
636 // Update the size of the current meta-block and continue emitting commands. | 683 /* Update the size of the current meta-block and continue emitting commands. |
637 // We can do this because the current size and the new size both have 5 | 684 We can do this because the current size and the new size both have 5 |
638 // nibbles. | 685 nibbles. */ |
639 total_block_size += block_size; | 686 total_block_size += block_size; |
640 UpdateBits(20, static_cast<uint32_t>(total_block_size - 1), | 687 UpdateBits(20, (uint32_t)(total_block_size - 1), mlen_storage_ix, storage); |
641 mlen_storage_ix, storage); | |
642 goto emit_commands; | 688 goto emit_commands; |
643 } | 689 } |
644 | 690 |
645 // Emit the remaining bytes as literals. | 691 /* Emit the remaining bytes as literals. */ |
646 if (next_emit < ip_end) { | 692 if (next_emit < ip_end) { |
647 const size_t insert = static_cast<size_t>(ip_end - next_emit); | 693 const size_t insert = (size_t)(ip_end - next_emit); |
648 if (PREDICT_TRUE(insert < 6210)) { | 694 if (BROTLI_PREDICT_TRUE(insert < 6210)) { |
649 EmitInsertLen(insert, cmd_depth, cmd_bits, cmd_histo, | 695 EmitInsertLen(insert, cmd_depth, cmd_bits, cmd_histo, |
650 storage_ix, storage); | 696 storage_ix, storage); |
651 EmitLiterals(next_emit, insert, lit_depth, lit_bits, storage_ix, storage); | 697 EmitLiterals(next_emit, insert, lit_depth, lit_bits, storage_ix, storage); |
652 } else if (ShouldUseUncompressedMode(metablock_start, next_emit, insert, | 698 } else if (ShouldUseUncompressedMode(metablock_start, next_emit, insert, |
653 lit_depth)) { | 699 literal_ratio)) { |
654 EmitUncompressedMetaBlock(metablock_start, ip_end, mlen_storage_ix - 3, | 700 EmitUncompressedMetaBlock(metablock_start, ip_end, mlen_storage_ix - 3, |
655 storage_ix, storage); | 701 storage_ix, storage); |
656 } else { | 702 } else { |
657 EmitLongInsertLen(insert, cmd_depth, cmd_bits, cmd_histo, | 703 EmitLongInsertLen(insert, cmd_depth, cmd_bits, cmd_histo, |
658 storage_ix, storage); | 704 storage_ix, storage); |
659 EmitLiterals(next_emit, insert, lit_depth, lit_bits, | 705 EmitLiterals(next_emit, insert, lit_depth, lit_bits, |
660 storage_ix, storage); | 706 storage_ix, storage); |
661 } | 707 } |
662 } | 708 } |
663 next_emit = ip_end; | 709 next_emit = ip_end; |
664 | 710 |
665 next_block: | 711 next_block: |
666 // If we have more data, write a new meta-block header and prefix codes and | 712 /* If we have more data, write a new meta-block header and prefix codes and |
667 // then continue emitting commands. | 713 then continue emitting commands. */ |
668 if (input_size > 0) { | 714 if (input_size > 0) { |
669 metablock_start = input; | 715 metablock_start = input; |
670 block_size = std::min(input_size, kFirstBlockSize); | 716 block_size = BROTLI_MIN(size_t, input_size, kFirstBlockSize); |
671 total_block_size = block_size; | 717 total_block_size = block_size; |
672 // Save the bit position of the MLEN field of the meta-block header, so that | 718 /* Save the bit position of the MLEN field of the meta-block header, so that |
673 // we can update it later if we decide to extend this meta-block. | 719 we can update it later if we decide to extend this meta-block. */ |
674 mlen_storage_ix = *storage_ix + 3; | 720 mlen_storage_ix = *storage_ix + 3; |
675 StoreMetaBlockHeader(block_size, 0, storage_ix, storage); | 721 BrotliStoreMetaBlockHeader(block_size, 0, storage_ix, storage); |
676 // No block splits, no contexts. | 722 /* No block splits, no contexts. */ |
677 WriteBits(13, 0, storage_ix, storage); | 723 BrotliWriteBits(13, 0, storage_ix, storage); |
678 memset(lit_depth, 0, sizeof(lit_depth)); | 724 literal_ratio = BuildAndStoreLiteralPrefixCode( |
679 memset(lit_bits, 0, sizeof(lit_bits)); | 725 m, input, block_size, lit_depth, lit_bits, storage_ix, storage); |
680 BuildAndStoreLiteralPrefixCode(input, block_size, lit_depth, lit_bits, | 726 if (BROTLI_IS_OOM(m)) return; |
681 storage_ix, storage); | |
682 BuildAndStoreCommandPrefixCode(cmd_histo, cmd_depth, cmd_bits, | 727 BuildAndStoreCommandPrefixCode(cmd_histo, cmd_depth, cmd_bits, |
683 storage_ix, storage); | 728 storage_ix, storage); |
684 goto emit_commands; | 729 goto emit_commands; |
685 } | 730 } |
686 | 731 |
687 if (is_last) { | 732 if (is_last) { |
688 WriteBits(1, 1, storage_ix, storage); // islast | 733 BrotliWriteBits(1, 1, storage_ix, storage); /* islast */ |
689 WriteBits(1, 1, storage_ix, storage); // isempty | 734 BrotliWriteBits(1, 1, storage_ix, storage); /* isempty */ |
690 *storage_ix = (*storage_ix + 7u) & ~7u; | 735 *storage_ix = (*storage_ix + 7u) & ~7u; |
691 } else { | 736 } else { |
692 // If this is not the last block, update the command and distance prefix | 737 /* If this is not the last block, update the command and distance prefix |
693 // codes for the next block and store the compressed forms. | 738 codes for the next block and store the compressed forms. */ |
694 cmd_code[0] = 0; | 739 cmd_code[0] = 0; |
695 *cmd_code_numbits = 0; | 740 *cmd_code_numbits = 0; |
696 BuildAndStoreCommandPrefixCode(cmd_histo, cmd_depth, cmd_bits, | 741 BuildAndStoreCommandPrefixCode(cmd_histo, cmd_depth, cmd_bits, |
697 cmd_code_numbits, cmd_code); | 742 cmd_code_numbits, cmd_code); |
698 } | 743 } |
699 } | 744 } |
700 | 745 |
701 } // namespace brotli | 746 #define FOR_TABLE_BITS_(X) X(9) X(11) X(13) X(15) |
| 747 |
| 748 #define BAKE_METHOD_PARAM_(B) \ |
| 749 static BROTLI_NOINLINE void BrotliCompressFragmentFastImpl ## B( \ |
| 750 MemoryManager* m, const uint8_t* input, size_t input_size, \ |
| 751 BROTLI_BOOL is_last, int* table, uint8_t cmd_depth[128], \ |
| 752 uint16_t cmd_bits[128], size_t* cmd_code_numbits, uint8_t* cmd_code, \ |
| 753 size_t* storage_ix, uint8_t* storage) { \ |
| 754 BrotliCompressFragmentFastImpl(m, input, input_size, is_last, table, B, \ |
| 755 cmd_depth, cmd_bits, cmd_code_numbits, cmd_code, storage_ix, storage); \ |
| 756 } |
| 757 FOR_TABLE_BITS_(BAKE_METHOD_PARAM_) |
| 758 #undef BAKE_METHOD_PARAM_ |
| 759 |
| 760 void BrotliCompressFragmentFast( |
| 761 MemoryManager* m, const uint8_t* input, size_t input_size, |
| 762 BROTLI_BOOL is_last, int* table, size_t table_size, uint8_t cmd_depth[128], |
| 763 uint16_t cmd_bits[128], size_t* cmd_code_numbits, uint8_t* cmd_code, |
| 764 size_t* storage_ix, uint8_t* storage) { |
| 765 const size_t table_bits = Log2FloorNonZero(table_size); |
| 766 switch (table_bits) { |
| 767 #define CASE_(B) \ |
| 768 case B: \ |
| 769 BrotliCompressFragmentFastImpl ## B( \ |
| 770 m, input, input_size, is_last, table, cmd_depth, cmd_bits, \ |
| 771 cmd_code_numbits, cmd_code, storage_ix, storage); \ |
| 772 break; |
| 773 FOR_TABLE_BITS_(CASE_) |
| 774 #undef CASE_ |
| 775 default: assert(0); break; |
| 776 } |
| 777 } |
| 778 |
| 779 #undef FOR_TABLE_BITS_ |
| 780 |
| 781 #if defined(__cplusplus) || defined(c_plusplus) |
| 782 } /* extern "C" */ |
| 783 #endif |
OLD | NEW |