| 1 | /* ****************************************************************** |
| 2 | * Huffman encoder, part of New Generation Entropy library |
| 3 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
| 4 | * |
| 5 | * You can contact the author at : |
| 6 | * - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy |
| 7 | * - Public forum : https://groups.google.com/forum/#!forum/lz4c |
| 8 | * |
| 9 | * This source code is licensed under both the BSD-style license (found in the |
| 10 | * LICENSE file in the root directory of this source tree) and the GPLv2 (found |
| 11 | * in the COPYING file in the root directory of this source tree). |
| 12 | * You may select, at your option, one of the above-listed licenses. |
| 13 | ****************************************************************** */ |
| 14 | |
| 15 | /* ************************************************************** |
| 16 | * Compiler specifics |
| 17 | ****************************************************************/ |
| 18 | #ifdef _MSC_VER /* Visual Studio */ |
| 19 | # pragma warning(disable : 4127) /* disable: C4127: conditional expression is constant */ |
| 20 | #endif |
| 21 | |
| 22 | |
| 23 | /* ************************************************************** |
| 24 | * Includes |
| 25 | ****************************************************************/ |
| 26 | #include "../common/zstd_deps.h" /* ZSTD_memcpy, ZSTD_memset */ |
| 27 | #include "../common/compiler.h" |
| 28 | #include "../common/bitstream.h" |
| 29 | #include "hist.h" |
| 30 | #define FSE_STATIC_LINKING_ONLY /* FSE_optimalTableLog_internal */ |
| 31 | #include "../common/fse.h" /* header compression */ |
| 32 | #include "../common/huf.h" |
| 33 | #include "../common/error_private.h" |
| 34 | #include "../common/bits.h" /* ZSTD_highbit32 */ |
| 35 | |
| 36 | |
| 37 | /* ************************************************************** |
| 38 | * Error Management |
| 39 | ****************************************************************/ |
| 40 | #define HUF_isError ERR_isError |
| 41 | #define HUF_STATIC_ASSERT(c) DEBUG_STATIC_ASSERT(c) /* use only *after* variable declarations */ |
| 42 | |
| 43 | |
| 44 | /* ************************************************************** |
| 45 | * Required declarations |
| 46 | ****************************************************************/ |
| 47 | typedef struct nodeElt_s { |
| 48 | U32 count; |
| 49 | U16 parent; |
| 50 | BYTE byte; |
| 51 | BYTE nbBits; |
| 52 | } nodeElt; |
| 53 | |
| 54 | |
| 55 | /* ************************************************************** |
| 56 | * Debug Traces |
| 57 | ****************************************************************/ |
| 58 | |
| 59 | #if DEBUGLEVEL >= 2 |
| 60 | |
| 61 | static size_t showU32(const U32* arr, size_t size) |
| 62 | { |
| 63 | size_t u; |
| 64 | for (u=0; u<size; u++) { |
| 65 | RAWLOG(6, " %u", arr[u]); (void)arr; |
| 66 | } |
| 67 | RAWLOG(6, " \n"); |
| 68 | return size; |
| 69 | } |
| 70 | |
| 71 | static size_t HUF_getNbBits(HUF_CElt elt); |
| 72 | |
| 73 | static size_t showCTableBits(const HUF_CElt* ctable, size_t size) |
| 74 | { |
| 75 | size_t u; |
| 76 | for (u=0; u<size; u++) { |
| 77 | RAWLOG(6, " %zu", HUF_getNbBits(ctable[u])); (void)ctable; |
| 78 | } |
| 79 | RAWLOG(6, " \n"); |
| 80 | return size; |
| 81 | |
| 82 | } |
| 83 | |
| 84 | static size_t showHNodeSymbols(const nodeElt* hnode, size_t size) |
| 85 | { |
| 86 | size_t u; |
| 87 | for (u=0; u<size; u++) { |
| 88 | RAWLOG(6, " %u", hnode[u].byte); (void)hnode; |
| 89 | } |
| 90 | RAWLOG(6, " \n"); |
| 91 | return size; |
| 92 | } |
| 93 | |
| 94 | static size_t showHNodeBits(const nodeElt* hnode, size_t size) |
| 95 | { |
| 96 | size_t u; |
| 97 | for (u=0; u<size; u++) { |
| 98 | RAWLOG(6, " %u", hnode[u].nbBits); (void)hnode; |
| 99 | } |
| 100 | RAWLOG(6, " \n"); |
| 101 | return size; |
| 102 | } |
| 103 | |
| 104 | #endif |
| 105 | |
| 106 | |
| 107 | /* ******************************************************* |
| 108 | * HUF : Huffman block compression |
| 109 | *********************************************************/ |
| 110 | #define HUF_WORKSPACE_MAX_ALIGNMENT 8 |
| 111 | |
| 112 | static void* HUF_alignUpWorkspace(void* workspace, size_t* workspaceSizePtr, size_t align) |
| 113 | { |
| 114 | size_t const mask = align - 1; |
| 115 | size_t const rem = (size_t)workspace & mask; |
| 116 | size_t const add = (align - rem) & mask; |
| 117 | BYTE* const aligned = (BYTE*)workspace + add; |
| 118 | assert((align & (align - 1)) == 0); /* pow 2 */ |
| 119 | assert(align <= HUF_WORKSPACE_MAX_ALIGNMENT); |
| 120 | if (*workspaceSizePtr >= add) { |
| 121 | assert(add < align); |
| 122 | assert(((size_t)aligned & mask) == 0); |
| 123 | *workspaceSizePtr -= add; |
| 124 | return aligned; |
| 125 | } else { |
| 126 | *workspaceSizePtr = 0; |
| 127 | return NULL; |
| 128 | } |
| 129 | } |
| 130 | |
| 131 | |
| 132 | /* HUF_compressWeights() : |
| 133 | * Same as FSE_compress(), but dedicated to huff0's weights compression. |
| 134 | * The use case needs much less stack memory. |
| 135 | * Note : all elements within weightTable are supposed to be <= HUF_TABLELOG_MAX. |
| 136 | */ |
| 137 | #define MAX_FSE_TABLELOG_FOR_HUFF_HEADER 6 |
| 138 | |
| 139 | typedef struct { |
| 140 | FSE_CTable CTable[FSE_CTABLE_SIZE_U32(MAX_FSE_TABLELOG_FOR_HUFF_HEADER, HUF_TABLELOG_MAX)]; |
| 141 | U32 scratchBuffer[FSE_BUILD_CTABLE_WORKSPACE_SIZE_U32(HUF_TABLELOG_MAX, MAX_FSE_TABLELOG_FOR_HUFF_HEADER)]; |
| 142 | unsigned count[HUF_TABLELOG_MAX+1]; |
| 143 | S16 norm[HUF_TABLELOG_MAX+1]; |
| 144 | } HUF_CompressWeightsWksp; |
| 145 | |
| 146 | static size_t |
| 147 | HUF_compressWeights(void* dst, size_t dstSize, |
| 148 | const void* weightTable, size_t wtSize, |
| 149 | void* workspace, size_t workspaceSize) |
| 150 | { |
| 151 | BYTE* const ostart = (BYTE*) dst; |
| 152 | BYTE* op = ostart; |
| 153 | BYTE* const oend = ostart + dstSize; |
| 154 | |
| 155 | unsigned maxSymbolValue = HUF_TABLELOG_MAX; |
| 156 | U32 tableLog = MAX_FSE_TABLELOG_FOR_HUFF_HEADER; |
| 157 | HUF_CompressWeightsWksp* wksp = (HUF_CompressWeightsWksp*)HUF_alignUpWorkspace(workspace, &workspaceSize, ZSTD_ALIGNOF(U32)); |
| 158 | |
| 159 | if (workspaceSize < sizeof(HUF_CompressWeightsWksp)) return ERROR(GENERIC); |
| 160 | |
| 161 | /* init conditions */ |
| 162 | if (wtSize <= 1) return 0; /* Not compressible */ |
| 163 | |
| 164 | /* Scan input and build symbol stats */ |
| 165 | { unsigned const maxCount = HIST_count_simple(wksp->count, &maxSymbolValue, weightTable, wtSize); /* never fails */ |
| 166 | if (maxCount == wtSize) return 1; /* only a single symbol in src : rle */ |
| 167 | if (maxCount == 1) return 0; /* each symbol present maximum once => not compressible */ |
| 168 | } |
| 169 | |
| 170 | tableLog = FSE_optimalTableLog(tableLog, wtSize, maxSymbolValue); |
| 171 | CHECK_F( FSE_normalizeCount(wksp->norm, tableLog, wksp->count, wtSize, maxSymbolValue, /* useLowProbCount */ 0) ); |
| 172 | |
| 173 | /* Write table description header */ |
| 174 | { CHECK_V_F(hSize, FSE_writeNCount(op, (size_t)(oend-op), wksp->norm, maxSymbolValue, tableLog) ); |
| 175 | op += hSize; |
| 176 | } |
| 177 | |
| 178 | /* Compress */ |
| 179 | CHECK_F( FSE_buildCTable_wksp(wksp->CTable, wksp->norm, maxSymbolValue, tableLog, wksp->scratchBuffer, sizeof(wksp->scratchBuffer)) ); |
| 180 | { CHECK_V_F(cSize, FSE_compress_usingCTable(op, (size_t)(oend - op), weightTable, wtSize, wksp->CTable) ); |
| 181 | if (cSize == 0) return 0; /* not enough space for compressed data */ |
| 182 | op += cSize; |
| 183 | } |
| 184 | |
| 185 | return (size_t)(op-ostart); |
| 186 | } |
| 187 | |
| 188 | static size_t HUF_getNbBits(HUF_CElt elt) |
| 189 | { |
| 190 | return elt & 0xFF; |
| 191 | } |
| 192 | |
| 193 | static size_t HUF_getNbBitsFast(HUF_CElt elt) |
| 194 | { |
| 195 | return elt; |
| 196 | } |
| 197 | |
| 198 | static size_t HUF_getValue(HUF_CElt elt) |
| 199 | { |
| 200 | return elt & ~(size_t)0xFF; |
| 201 | } |
| 202 | |
| 203 | static size_t HUF_getValueFast(HUF_CElt elt) |
| 204 | { |
| 205 | return elt; |
| 206 | } |
| 207 | |
| 208 | static void HUF_setNbBits(HUF_CElt* elt, size_t nbBits) |
| 209 | { |
| 210 | assert(nbBits <= HUF_TABLELOG_ABSOLUTEMAX); |
| 211 | *elt = nbBits; |
| 212 | } |
| 213 | |
| 214 | static void HUF_setValue(HUF_CElt* elt, size_t value) |
| 215 | { |
| 216 | size_t const nbBits = HUF_getNbBits(*elt); |
| 217 | if (nbBits > 0) { |
| 218 | assert((value >> nbBits) == 0); |
| 219 | *elt |= value << (sizeof(HUF_CElt) * 8 - nbBits); |
| 220 | } |
| 221 | } |
| 222 | |
| 223 | typedef struct { |
| 224 | HUF_CompressWeightsWksp wksp; |
| 225 | BYTE bitsToWeight[HUF_TABLELOG_MAX + 1]; /* precomputed conversion table */ |
| 226 | BYTE huffWeight[HUF_SYMBOLVALUE_MAX]; |
| 227 | } HUF_WriteCTableWksp; |
| 228 | |
| 229 | size_t HUF_writeCTable_wksp(void* dst, size_t maxDstSize, |
| 230 | const HUF_CElt* CTable, unsigned maxSymbolValue, unsigned huffLog, |
| 231 | void* workspace, size_t workspaceSize) |
| 232 | { |
| 233 | HUF_CElt const* const ct = CTable + 1; |
| 234 | BYTE* op = (BYTE*)dst; |
| 235 | U32 n; |
| 236 | HUF_WriteCTableWksp* wksp = (HUF_WriteCTableWksp*)HUF_alignUpWorkspace(workspace, &workspaceSize, ZSTD_ALIGNOF(U32)); |
| 237 | |
| 238 | HUF_STATIC_ASSERT(HUF_CTABLE_WORKSPACE_SIZE >= sizeof(HUF_WriteCTableWksp)); |
| 239 | |
| 240 | /* check conditions */ |
| 241 | if (workspaceSize < sizeof(HUF_WriteCTableWksp)) return ERROR(GENERIC); |
| 242 | if (maxSymbolValue > HUF_SYMBOLVALUE_MAX) return ERROR(maxSymbolValue_tooLarge); |
| 243 | |
| 244 | /* convert to weight */ |
| 245 | wksp->bitsToWeight[0] = 0; |
| 246 | for (n=1; n<huffLog+1; n++) |
| 247 | wksp->bitsToWeight[n] = (BYTE)(huffLog + 1 - n); |
| 248 | for (n=0; n<maxSymbolValue; n++) |
| 249 | wksp->huffWeight[n] = wksp->bitsToWeight[HUF_getNbBits(ct[n])]; |
| 250 | |
| 251 | /* attempt weights compression by FSE */ |
| 252 | if (maxDstSize < 1) return ERROR(dstSize_tooSmall); |
| 253 | { CHECK_V_F(hSize, HUF_compressWeights(op+1, maxDstSize-1, wksp->huffWeight, maxSymbolValue, &wksp->wksp, sizeof(wksp->wksp)) ); |
| 254 | if ((hSize>1) & (hSize < maxSymbolValue/2)) { /* FSE compressed */ |
| 255 | op[0] = (BYTE)hSize; |
| 256 | return hSize+1; |
| 257 | } } |
| 258 | |
| 259 | /* write raw values as 4-bits (max : 15) */ |
| 260 | if (maxSymbolValue > (256-128)) return ERROR(GENERIC); /* should not happen : likely means source cannot be compressed */ |
| 261 | if (((maxSymbolValue+1)/2) + 1 > maxDstSize) return ERROR(dstSize_tooSmall); /* not enough space within dst buffer */ |
| 262 | op[0] = (BYTE)(128 /*special case*/ + (maxSymbolValue-1)); |
| 263 | wksp->huffWeight[maxSymbolValue] = 0; /* to be sure it doesn't cause msan issue in final combination */ |
| 264 | for (n=0; n<maxSymbolValue; n+=2) |
| 265 | op[(n/2)+1] = (BYTE)((wksp->huffWeight[n] << 4) + wksp->huffWeight[n+1]); |
| 266 | return ((maxSymbolValue+1)/2) + 1; |
| 267 | } |
| 268 | |
| 269 | |
| 270 | size_t HUF_readCTable (HUF_CElt* CTable, unsigned* maxSymbolValuePtr, const void* src, size_t srcSize, unsigned* hasZeroWeights) |
| 271 | { |
| 272 | BYTE huffWeight[HUF_SYMBOLVALUE_MAX + 1]; /* init not required, even though some static analyzer may complain */ |
| 273 | U32 rankVal[HUF_TABLELOG_ABSOLUTEMAX + 1]; /* large enough for values from 0 to 16 */ |
| 274 | U32 tableLog = 0; |
| 275 | U32 nbSymbols = 0; |
| 276 | HUF_CElt* const ct = CTable + 1; |
| 277 | |
| 278 | /* get symbol weights */ |
| 279 | CHECK_V_F(readSize, HUF_readStats(huffWeight, HUF_SYMBOLVALUE_MAX+1, rankVal, &nbSymbols, &tableLog, src, srcSize)); |
| 280 | *hasZeroWeights = (rankVal[0] > 0); |
| 281 | |
| 282 | /* check result */ |
| 283 | if (tableLog > HUF_TABLELOG_MAX) return ERROR(tableLog_tooLarge); |
| 284 | if (nbSymbols > *maxSymbolValuePtr+1) return ERROR(maxSymbolValue_tooSmall); |
| 285 | |
| 286 | CTable[0] = tableLog; |
| 287 | |
| 288 | /* Prepare base value per rank */ |
| 289 | { U32 n, nextRankStart = 0; |
| 290 | for (n=1; n<=tableLog; n++) { |
| 291 | U32 curr = nextRankStart; |
| 292 | nextRankStart += (rankVal[n] << (n-1)); |
| 293 | rankVal[n] = curr; |
| 294 | } } |
| 295 | |
| 296 | /* fill nbBits */ |
| 297 | { U32 n; for (n=0; n<nbSymbols; n++) { |
| 298 | const U32 w = huffWeight[n]; |
| 299 | HUF_setNbBits(ct + n, (BYTE)(tableLog + 1 - w) & -(w != 0)); |
| 300 | } } |
| 301 | |
| 302 | /* fill val */ |
| 303 | { U16 nbPerRank[HUF_TABLELOG_MAX+2] = {0}; /* support w=0=>n=tableLog+1 */ |
| 304 | U16 valPerRank[HUF_TABLELOG_MAX+2] = {0}; |
| 305 | { U32 n; for (n=0; n<nbSymbols; n++) nbPerRank[HUF_getNbBits(ct[n])]++; } |
| 306 | /* determine stating value per rank */ |
| 307 | valPerRank[tableLog+1] = 0; /* for w==0 */ |
| 308 | { U16 min = 0; |
| 309 | U32 n; for (n=tableLog; n>0; n--) { /* start at n=tablelog <-> w=1 */ |
| 310 | valPerRank[n] = min; /* get starting value within each rank */ |
| 311 | min += nbPerRank[n]; |
| 312 | min >>= 1; |
| 313 | } } |
| 314 | /* assign value within rank, symbol order */ |
| 315 | { U32 n; for (n=0; n<nbSymbols; n++) HUF_setValue(ct + n, valPerRank[HUF_getNbBits(ct[n])]++); } |
| 316 | } |
| 317 | |
| 318 | *maxSymbolValuePtr = nbSymbols - 1; |
| 319 | return readSize; |
| 320 | } |
| 321 | |
| 322 | U32 HUF_getNbBitsFromCTable(HUF_CElt const* CTable, U32 symbolValue) |
| 323 | { |
| 324 | const HUF_CElt* const ct = CTable + 1; |
| 325 | assert(symbolValue <= HUF_SYMBOLVALUE_MAX); |
| 326 | return (U32)HUF_getNbBits(ct[symbolValue]); |
| 327 | } |
| 328 | |
| 329 | |
| 330 | /** |
| 331 | * HUF_setMaxHeight(): |
| 332 | * Try to enforce @targetNbBits on the Huffman tree described in @huffNode. |
| 333 | * |
| 334 | * It attempts to convert all nodes with nbBits > @targetNbBits |
| 335 | * to employ @targetNbBits instead. Then it adjusts the tree |
| 336 | * so that it remains a valid canonical Huffman tree. |
| 337 | * |
| 338 | * @pre The sum of the ranks of each symbol == 2^largestBits, |
| 339 | * where largestBits == huffNode[lastNonNull].nbBits. |
| 340 | * @post The sum of the ranks of each symbol == 2^largestBits, |
| 341 | * where largestBits is the return value (expected <= targetNbBits). |
| 342 | * |
| 343 | * @param huffNode The Huffman tree modified in place to enforce targetNbBits. |
| 344 | * It's presumed sorted, from most frequent to rarest symbol. |
| 345 | * @param lastNonNull The symbol with the lowest count in the Huffman tree. |
| 346 | * @param targetNbBits The allowed number of bits, which the Huffman tree |
| 347 | * may not respect. After this function the Huffman tree will |
| 348 | * respect targetNbBits. |
| 349 | * @return The maximum number of bits of the Huffman tree after adjustment. |
| 350 | */ |
| 351 | static U32 HUF_setMaxHeight(nodeElt* huffNode, U32 lastNonNull, U32 targetNbBits) |
| 352 | { |
| 353 | const U32 largestBits = huffNode[lastNonNull].nbBits; |
| 354 | /* early exit : no elt > targetNbBits, so the tree is already valid. */ |
| 355 | if (largestBits <= targetNbBits) return largestBits; |
| 356 | |
| 357 | DEBUGLOG(5, "HUF_setMaxHeight (targetNbBits = %u)", targetNbBits); |
| 358 | |
| 359 | /* there are several too large elements (at least >= 2) */ |
| 360 | { int totalCost = 0; |
| 361 | const U32 baseCost = 1 << (largestBits - targetNbBits); |
| 362 | int n = (int)lastNonNull; |
| 363 | |
| 364 | /* Adjust any ranks > targetNbBits to targetNbBits. |
| 365 | * Compute totalCost, which is how far the sum of the ranks is |
| 366 | * we are over 2^largestBits after adjust the offending ranks. |
| 367 | */ |
| 368 | while (huffNode[n].nbBits > targetNbBits) { |
| 369 | totalCost += baseCost - (1 << (largestBits - huffNode[n].nbBits)); |
| 370 | huffNode[n].nbBits = (BYTE)targetNbBits; |
| 371 | n--; |
| 372 | } |
| 373 | /* n stops at huffNode[n].nbBits <= targetNbBits */ |
| 374 | assert(huffNode[n].nbBits <= targetNbBits); |
| 375 | /* n end at index of smallest symbol using < targetNbBits */ |
| 376 | while (huffNode[n].nbBits == targetNbBits) --n; |
| 377 | |
| 378 | /* renorm totalCost from 2^largestBits to 2^targetNbBits |
| 379 | * note : totalCost is necessarily a multiple of baseCost */ |
| 380 | assert(((U32)totalCost & (baseCost - 1)) == 0); |
| 381 | totalCost >>= (largestBits - targetNbBits); |
| 382 | assert(totalCost > 0); |
| 383 | |
| 384 | /* repay normalized cost */ |
| 385 | { U32 const noSymbol = 0xF0F0F0F0; |
| 386 | U32 rankLast[HUF_TABLELOG_MAX+2]; |
| 387 | |
| 388 | /* Get pos of last (smallest = lowest cum. count) symbol per rank */ |
| 389 | ZSTD_memset(rankLast, 0xF0, sizeof(rankLast)); |
| 390 | { U32 currentNbBits = targetNbBits; |
| 391 | int pos; |
| 392 | for (pos=n ; pos >= 0; pos--) { |
| 393 | if (huffNode[pos].nbBits >= currentNbBits) continue; |
| 394 | currentNbBits = huffNode[pos].nbBits; /* < targetNbBits */ |
| 395 | rankLast[targetNbBits-currentNbBits] = (U32)pos; |
| 396 | } } |
| 397 | |
| 398 | while (totalCost > 0) { |
| 399 | /* Try to reduce the next power of 2 above totalCost because we |
| 400 | * gain back half the rank. |
| 401 | */ |
| 402 | U32 nBitsToDecrease = ZSTD_highbit32((U32)totalCost) + 1; |
| 403 | for ( ; nBitsToDecrease > 1; nBitsToDecrease--) { |
| 404 | U32 const highPos = rankLast[nBitsToDecrease]; |
| 405 | U32 const lowPos = rankLast[nBitsToDecrease-1]; |
| 406 | if (highPos == noSymbol) continue; |
| 407 | /* Decrease highPos if no symbols of lowPos or if it is |
| 408 | * not cheaper to remove 2 lowPos than highPos. |
| 409 | */ |
| 410 | if (lowPos == noSymbol) break; |
| 411 | { U32 const highTotal = huffNode[highPos].count; |
| 412 | U32 const lowTotal = 2 * huffNode[lowPos].count; |
| 413 | if (highTotal <= lowTotal) break; |
| 414 | } } |
| 415 | /* only triggered when no more rank 1 symbol left => find closest one (note : there is necessarily at least one !) */ |
| 416 | assert(rankLast[nBitsToDecrease] != noSymbol || nBitsToDecrease == 1); |
| 417 | /* HUF_MAX_TABLELOG test just to please gcc 5+; but it should not be necessary */ |
| 418 | while ((nBitsToDecrease<=HUF_TABLELOG_MAX) && (rankLast[nBitsToDecrease] == noSymbol)) |
| 419 | nBitsToDecrease++; |
| 420 | assert(rankLast[nBitsToDecrease] != noSymbol); |
| 421 | /* Increase the number of bits to gain back half the rank cost. */ |
| 422 | totalCost -= 1 << (nBitsToDecrease-1); |
| 423 | huffNode[rankLast[nBitsToDecrease]].nbBits++; |
| 424 | |
| 425 | /* Fix up the new rank. |
| 426 | * If the new rank was empty, this symbol is now its smallest. |
| 427 | * Otherwise, this symbol will be the largest in the new rank so no adjustment. |
| 428 | */ |
| 429 | if (rankLast[nBitsToDecrease-1] == noSymbol) |
| 430 | rankLast[nBitsToDecrease-1] = rankLast[nBitsToDecrease]; |
| 431 | /* Fix up the old rank. |
| 432 | * If the symbol was at position 0, meaning it was the highest weight symbol in the tree, |
| 433 | * it must be the only symbol in its rank, so the old rank now has no symbols. |
| 434 | * Otherwise, since the Huffman nodes are sorted by count, the previous position is now |
| 435 | * the smallest node in the rank. If the previous position belongs to a different rank, |
| 436 | * then the rank is now empty. |
| 437 | */ |
| 438 | if (rankLast[nBitsToDecrease] == 0) /* special case, reached largest symbol */ |
| 439 | rankLast[nBitsToDecrease] = noSymbol; |
| 440 | else { |
| 441 | rankLast[nBitsToDecrease]--; |
| 442 | if (huffNode[rankLast[nBitsToDecrease]].nbBits != targetNbBits-nBitsToDecrease) |
| 443 | rankLast[nBitsToDecrease] = noSymbol; /* this rank is now empty */ |
| 444 | } |
| 445 | } /* while (totalCost > 0) */ |
| 446 | |
| 447 | /* If we've removed too much weight, then we have to add it back. |
| 448 | * To avoid overshooting again, we only adjust the smallest rank. |
| 449 | * We take the largest nodes from the lowest rank 0 and move them |
| 450 | * to rank 1. There's guaranteed to be enough rank 0 symbols because |
| 451 | * TODO. |
| 452 | */ |
| 453 | while (totalCost < 0) { /* Sometimes, cost correction overshoot */ |
| 454 | /* special case : no rank 1 symbol (using targetNbBits-1); |
| 455 | * let's create one from largest rank 0 (using targetNbBits). |
| 456 | */ |
| 457 | if (rankLast[1] == noSymbol) { |
| 458 | while (huffNode[n].nbBits == targetNbBits) n--; |
| 459 | huffNode[n+1].nbBits--; |
| 460 | assert(n >= 0); |
| 461 | rankLast[1] = (U32)(n+1); |
| 462 | totalCost++; |
| 463 | continue; |
| 464 | } |
| 465 | huffNode[ rankLast[1] + 1 ].nbBits--; |
| 466 | rankLast[1]++; |
| 467 | totalCost ++; |
| 468 | } |
| 469 | } /* repay normalized cost */ |
| 470 | } /* there are several too large elements (at least >= 2) */ |
| 471 | |
| 472 | return targetNbBits; |
| 473 | } |
| 474 | |
| 475 | typedef struct { |
| 476 | U16 base; |
| 477 | U16 curr; |
| 478 | } rankPos; |
| 479 | |
| 480 | typedef nodeElt huffNodeTable[2 * (HUF_SYMBOLVALUE_MAX + 1)]; |
| 481 | |
| 482 | /* Number of buckets available for HUF_sort() */ |
| 483 | #define RANK_POSITION_TABLE_SIZE 192 |
| 484 | |
| 485 | typedef struct { |
| 486 | huffNodeTable huffNodeTbl; |
| 487 | rankPos rankPosition[RANK_POSITION_TABLE_SIZE]; |
| 488 | } HUF_buildCTable_wksp_tables; |
| 489 | |
| 490 | /* RANK_POSITION_DISTINCT_COUNT_CUTOFF == Cutoff point in HUF_sort() buckets for which we use log2 bucketing. |
| 491 | * Strategy is to use as many buckets as possible for representing distinct |
| 492 | * counts while using the remainder to represent all "large" counts. |
| 493 | * |
| 494 | * To satisfy this requirement for 192 buckets, we can do the following: |
| 495 | * Let buckets 0-166 represent distinct counts of [0, 166] |
| 496 | * Let buckets 166 to 192 represent all remaining counts up to RANK_POSITION_MAX_COUNT_LOG using log2 bucketing. |
| 497 | */ |
| 498 | #define RANK_POSITION_MAX_COUNT_LOG 32 |
| 499 | #define RANK_POSITION_LOG_BUCKETS_BEGIN ((RANK_POSITION_TABLE_SIZE - 1) - RANK_POSITION_MAX_COUNT_LOG - 1 /* == 158 */) |
| 500 | #define RANK_POSITION_DISTINCT_COUNT_CUTOFF (RANK_POSITION_LOG_BUCKETS_BEGIN + ZSTD_highbit32(RANK_POSITION_LOG_BUCKETS_BEGIN) /* == 166 */) |
| 501 | |
| 502 | /* Return the appropriate bucket index for a given count. See definition of |
| 503 | * RANK_POSITION_DISTINCT_COUNT_CUTOFF for explanation of bucketing strategy. |
| 504 | */ |
| 505 | static U32 HUF_getIndex(U32 const count) { |
| 506 | return (count < RANK_POSITION_DISTINCT_COUNT_CUTOFF) |
| 507 | ? count |
| 508 | : ZSTD_highbit32(count) + RANK_POSITION_LOG_BUCKETS_BEGIN; |
| 509 | } |
| 510 | |
| 511 | /* Helper swap function for HUF_quickSortPartition() */ |
| 512 | static void HUF_swapNodes(nodeElt* a, nodeElt* b) { |
| 513 | nodeElt tmp = *a; |
| 514 | *a = *b; |
| 515 | *b = tmp; |
| 516 | } |
| 517 | |
| 518 | /* Returns 0 if the huffNode array is not sorted by descending count */ |
| 519 | MEM_STATIC int HUF_isSorted(nodeElt huffNode[], U32 const maxSymbolValue1) { |
| 520 | U32 i; |
| 521 | for (i = 1; i < maxSymbolValue1; ++i) { |
| 522 | if (huffNode[i].count > huffNode[i-1].count) { |
| 523 | return 0; |
| 524 | } |
| 525 | } |
| 526 | return 1; |
| 527 | } |
| 528 | |
| 529 | /* Insertion sort by descending order */ |
| 530 | HINT_INLINE void HUF_insertionSort(nodeElt huffNode[], int const low, int const high) { |
| 531 | int i; |
| 532 | int const size = high-low+1; |
| 533 | huffNode += low; |
| 534 | for (i = 1; i < size; ++i) { |
| 535 | nodeElt const key = huffNode[i]; |
| 536 | int j = i - 1; |
| 537 | while (j >= 0 && huffNode[j].count < key.count) { |
| 538 | huffNode[j + 1] = huffNode[j]; |
| 539 | j--; |
| 540 | } |
| 541 | huffNode[j + 1] = key; |
| 542 | } |
| 543 | } |
| 544 | |
| 545 | /* Pivot helper function for quicksort. */ |
| 546 | static int HUF_quickSortPartition(nodeElt arr[], int const low, int const high) { |
| 547 | /* Simply select rightmost element as pivot. "Better" selectors like |
| 548 | * median-of-three don't experimentally appear to have any benefit. |
| 549 | */ |
| 550 | U32 const pivot = arr[high].count; |
| 551 | int i = low - 1; |
| 552 | int j = low; |
| 553 | for ( ; j < high; j++) { |
| 554 | if (arr[j].count > pivot) { |
| 555 | i++; |
| 556 | HUF_swapNodes(&arr[i], &arr[j]); |
| 557 | } |
| 558 | } |
| 559 | HUF_swapNodes(&arr[i + 1], &arr[high]); |
| 560 | return i + 1; |
| 561 | } |
| 562 | |
| 563 | /* Classic quicksort by descending with partially iterative calls |
| 564 | * to reduce worst case callstack size. |
| 565 | */ |
| 566 | static void HUF_simpleQuickSort(nodeElt arr[], int low, int high) { |
| 567 | int const kInsertionSortThreshold = 8; |
| 568 | if (high - low < kInsertionSortThreshold) { |
| 569 | HUF_insertionSort(arr, low, high); |
| 570 | return; |
| 571 | } |
| 572 | while (low < high) { |
| 573 | int const idx = HUF_quickSortPartition(arr, low, high); |
| 574 | if (idx - low < high - idx) { |
| 575 | HUF_simpleQuickSort(arr, low, idx - 1); |
| 576 | low = idx + 1; |
| 577 | } else { |
| 578 | HUF_simpleQuickSort(arr, idx + 1, high); |
| 579 | high = idx - 1; |
| 580 | } |
| 581 | } |
| 582 | } |
| 583 | |
| 584 | /** |
| 585 | * HUF_sort(): |
| 586 | * Sorts the symbols [0, maxSymbolValue] by count[symbol] in decreasing order. |
| 587 | * This is a typical bucket sorting strategy that uses either quicksort or insertion sort to sort each bucket. |
| 588 | * |
| 589 | * @param[out] huffNode Sorted symbols by decreasing count. Only members `.count` and `.byte` are filled. |
| 590 | * Must have (maxSymbolValue + 1) entries. |
| 591 | * @param[in] count Histogram of the symbols. |
| 592 | * @param[in] maxSymbolValue Maximum symbol value. |
| 593 | * @param rankPosition This is a scratch workspace. Must have RANK_POSITION_TABLE_SIZE entries. |
| 594 | */ |
| 595 | static void HUF_sort(nodeElt huffNode[], const unsigned count[], U32 const maxSymbolValue, rankPos rankPosition[]) { |
| 596 | U32 n; |
| 597 | U32 const maxSymbolValue1 = maxSymbolValue+1; |
| 598 | |
| 599 | /* Compute base and set curr to base. |
| 600 | * For symbol s let lowerRank = HUF_getIndex(count[n]) and rank = lowerRank + 1. |
| 601 | * See HUF_getIndex to see bucketing strategy. |
| 602 | * We attribute each symbol to lowerRank's base value, because we want to know where |
| 603 | * each rank begins in the output, so for rank R we want to count ranks R+1 and above. |
| 604 | */ |
| 605 | ZSTD_memset(rankPosition, 0, sizeof(*rankPosition) * RANK_POSITION_TABLE_SIZE); |
| 606 | for (n = 0; n < maxSymbolValue1; ++n) { |
| 607 | U32 lowerRank = HUF_getIndex(count[n]); |
| 608 | assert(lowerRank < RANK_POSITION_TABLE_SIZE - 1); |
| 609 | rankPosition[lowerRank].base++; |
| 610 | } |
| 611 | |
| 612 | assert(rankPosition[RANK_POSITION_TABLE_SIZE - 1].base == 0); |
| 613 | /* Set up the rankPosition table */ |
| 614 | for (n = RANK_POSITION_TABLE_SIZE - 1; n > 0; --n) { |
| 615 | rankPosition[n-1].base += rankPosition[n].base; |
| 616 | rankPosition[n-1].curr = rankPosition[n-1].base; |
| 617 | } |
| 618 | |
| 619 | /* Insert each symbol into their appropriate bucket, setting up rankPosition table. */ |
| 620 | for (n = 0; n < maxSymbolValue1; ++n) { |
| 621 | U32 const c = count[n]; |
| 622 | U32 const r = HUF_getIndex(c) + 1; |
| 623 | U32 const pos = rankPosition[r].curr++; |
| 624 | assert(pos < maxSymbolValue1); |
| 625 | huffNode[pos].count = c; |
| 626 | huffNode[pos].byte = (BYTE)n; |
| 627 | } |
| 628 | |
| 629 | /* Sort each bucket. */ |
| 630 | for (n = RANK_POSITION_DISTINCT_COUNT_CUTOFF; n < RANK_POSITION_TABLE_SIZE - 1; ++n) { |
| 631 | int const bucketSize = rankPosition[n].curr - rankPosition[n].base; |
| 632 | U32 const bucketStartIdx = rankPosition[n].base; |
| 633 | if (bucketSize > 1) { |
| 634 | assert(bucketStartIdx < maxSymbolValue1); |
| 635 | HUF_simpleQuickSort(huffNode + bucketStartIdx, 0, bucketSize-1); |
| 636 | } |
| 637 | } |
| 638 | |
| 639 | assert(HUF_isSorted(huffNode, maxSymbolValue1)); |
| 640 | } |
| 641 | |
| 642 | |
| 643 | /** HUF_buildCTable_wksp() : |
| 644 | * Same as HUF_buildCTable(), but using externally allocated scratch buffer. |
| 645 | * `workSpace` must be aligned on 4-bytes boundaries, and be at least as large as sizeof(HUF_buildCTable_wksp_tables). |
| 646 | */ |
| 647 | #define STARTNODE (HUF_SYMBOLVALUE_MAX+1) |
| 648 | |
| 649 | /* HUF_buildTree(): |
| 650 | * Takes the huffNode array sorted by HUF_sort() and builds an unlimited-depth Huffman tree. |
| 651 | * |
| 652 | * @param huffNode The array sorted by HUF_sort(). Builds the Huffman tree in this array. |
| 653 | * @param maxSymbolValue The maximum symbol value. |
| 654 | * @return The smallest node in the Huffman tree (by count). |
| 655 | */ |
| 656 | static int HUF_buildTree(nodeElt* huffNode, U32 maxSymbolValue) |
| 657 | { |
| 658 | nodeElt* const huffNode0 = huffNode - 1; |
| 659 | int nonNullRank; |
| 660 | int lowS, lowN; |
| 661 | int nodeNb = STARTNODE; |
| 662 | int n, nodeRoot; |
| 663 | DEBUGLOG(5, "HUF_buildTree (alphabet size = %u)", maxSymbolValue + 1); |
| 664 | /* init for parents */ |
| 665 | nonNullRank = (int)maxSymbolValue; |
| 666 | while(huffNode[nonNullRank].count == 0) nonNullRank--; |
| 667 | lowS = nonNullRank; nodeRoot = nodeNb + lowS - 1; lowN = nodeNb; |
| 668 | huffNode[nodeNb].count = huffNode[lowS].count + huffNode[lowS-1].count; |
| 669 | huffNode[lowS].parent = huffNode[lowS-1].parent = (U16)nodeNb; |
| 670 | nodeNb++; lowS-=2; |
| 671 | for (n=nodeNb; n<=nodeRoot; n++) huffNode[n].count = (U32)(1U<<30); |
| 672 | huffNode0[0].count = (U32)(1U<<31); /* fake entry, strong barrier */ |
| 673 | |
| 674 | /* create parents */ |
| 675 | while (nodeNb <= nodeRoot) { |
| 676 | int const n1 = (huffNode[lowS].count < huffNode[lowN].count) ? lowS-- : lowN++; |
| 677 | int const n2 = (huffNode[lowS].count < huffNode[lowN].count) ? lowS-- : lowN++; |
| 678 | huffNode[nodeNb].count = huffNode[n1].count + huffNode[n2].count; |
| 679 | huffNode[n1].parent = huffNode[n2].parent = (U16)nodeNb; |
| 680 | nodeNb++; |
| 681 | } |
| 682 | |
| 683 | /* distribute weights (unlimited tree height) */ |
| 684 | huffNode[nodeRoot].nbBits = 0; |
| 685 | for (n=nodeRoot-1; n>=STARTNODE; n--) |
| 686 | huffNode[n].nbBits = huffNode[ huffNode[n].parent ].nbBits + 1; |
| 687 | for (n=0; n<=nonNullRank; n++) |
| 688 | huffNode[n].nbBits = huffNode[ huffNode[n].parent ].nbBits + 1; |
| 689 | |
| 690 | DEBUGLOG(6, "Initial distribution of bits completed (%zu sorted symbols)", showHNodeBits(huffNode, maxSymbolValue+1)); |
| 691 | |
| 692 | return nonNullRank; |
| 693 | } |
| 694 | |
| 695 | /** |
| 696 | * HUF_buildCTableFromTree(): |
| 697 | * Build the CTable given the Huffman tree in huffNode. |
| 698 | * |
| 699 | * @param[out] CTable The output Huffman CTable. |
| 700 | * @param huffNode The Huffman tree. |
| 701 | * @param nonNullRank The last and smallest node in the Huffman tree. |
| 702 | * @param maxSymbolValue The maximum symbol value. |
| 703 | * @param maxNbBits The exact maximum number of bits used in the Huffman tree. |
| 704 | */ |
| 705 | static void HUF_buildCTableFromTree(HUF_CElt* CTable, nodeElt const* huffNode, int nonNullRank, U32 maxSymbolValue, U32 maxNbBits) |
| 706 | { |
| 707 | HUF_CElt* const ct = CTable + 1; |
| 708 | /* fill result into ctable (val, nbBits) */ |
| 709 | int n; |
| 710 | U16 nbPerRank[HUF_TABLELOG_MAX+1] = {0}; |
| 711 | U16 valPerRank[HUF_TABLELOG_MAX+1] = {0}; |
| 712 | int const alphabetSize = (int)(maxSymbolValue + 1); |
| 713 | for (n=0; n<=nonNullRank; n++) |
| 714 | nbPerRank[huffNode[n].nbBits]++; |
| 715 | /* determine starting value per rank */ |
| 716 | { U16 min = 0; |
| 717 | for (n=(int)maxNbBits; n>0; n--) { |
| 718 | valPerRank[n] = min; /* get starting value within each rank */ |
| 719 | min += nbPerRank[n]; |
| 720 | min >>= 1; |
| 721 | } } |
| 722 | for (n=0; n<alphabetSize; n++) |
| 723 | HUF_setNbBits(ct + huffNode[n].byte, huffNode[n].nbBits); /* push nbBits per symbol, symbol order */ |
| 724 | for (n=0; n<alphabetSize; n++) |
| 725 | HUF_setValue(ct + n, valPerRank[HUF_getNbBits(ct[n])]++); /* assign value within rank, symbol order */ |
| 726 | CTable[0] = maxNbBits; |
| 727 | } |
| 728 | |
| 729 | size_t |
| 730 | HUF_buildCTable_wksp(HUF_CElt* CTable, const unsigned* count, U32 maxSymbolValue, U32 maxNbBits, |
| 731 | void* workSpace, size_t wkspSize) |
| 732 | { |
| 733 | HUF_buildCTable_wksp_tables* const wksp_tables = |
| 734 | (HUF_buildCTable_wksp_tables*)HUF_alignUpWorkspace(workSpace, &wkspSize, ZSTD_ALIGNOF(U32)); |
| 735 | nodeElt* const huffNode0 = wksp_tables->huffNodeTbl; |
| 736 | nodeElt* const huffNode = huffNode0+1; |
| 737 | int nonNullRank; |
| 738 | |
| 739 | HUF_STATIC_ASSERT(HUF_CTABLE_WORKSPACE_SIZE == sizeof(HUF_buildCTable_wksp_tables)); |
| 740 | |
| 741 | DEBUGLOG(5, "HUF_buildCTable_wksp (alphabet size = %u)", maxSymbolValue+1); |
| 742 | |
| 743 | /* safety checks */ |
| 744 | if (wkspSize < sizeof(HUF_buildCTable_wksp_tables)) |
| 745 | return ERROR(workSpace_tooSmall); |
| 746 | if (maxNbBits == 0) maxNbBits = HUF_TABLELOG_DEFAULT; |
| 747 | if (maxSymbolValue > HUF_SYMBOLVALUE_MAX) |
| 748 | return ERROR(maxSymbolValue_tooLarge); |
| 749 | ZSTD_memset(huffNode0, 0, sizeof(huffNodeTable)); |
| 750 | |
| 751 | /* sort, decreasing order */ |
| 752 | HUF_sort(huffNode, count, maxSymbolValue, wksp_tables->rankPosition); |
| 753 | DEBUGLOG(6, "sorted symbols completed (%zu symbols)", showHNodeSymbols(huffNode, maxSymbolValue+1)); |
| 754 | |
| 755 | /* build tree */ |
| 756 | nonNullRank = HUF_buildTree(huffNode, maxSymbolValue); |
| 757 | |
| 758 | /* determine and enforce maxTableLog */ |
| 759 | maxNbBits = HUF_setMaxHeight(huffNode, (U32)nonNullRank, maxNbBits); |
| 760 | if (maxNbBits > HUF_TABLELOG_MAX) return ERROR(GENERIC); /* check fit into table */ |
| 761 | |
| 762 | HUF_buildCTableFromTree(CTable, huffNode, nonNullRank, maxSymbolValue, maxNbBits); |
| 763 | |
| 764 | return maxNbBits; |
| 765 | } |
| 766 | |
| 767 | size_t HUF_estimateCompressedSize(const HUF_CElt* CTable, const unsigned* count, unsigned maxSymbolValue) |
| 768 | { |
| 769 | HUF_CElt const* ct = CTable + 1; |
| 770 | size_t nbBits = 0; |
| 771 | int s; |
| 772 | for (s = 0; s <= (int)maxSymbolValue; ++s) { |
| 773 | nbBits += HUF_getNbBits(ct[s]) * count[s]; |
| 774 | } |
| 775 | return nbBits >> 3; |
| 776 | } |
| 777 | |
| 778 | int HUF_validateCTable(const HUF_CElt* CTable, const unsigned* count, unsigned maxSymbolValue) { |
| 779 | HUF_CElt const* ct = CTable + 1; |
| 780 | int bad = 0; |
| 781 | int s; |
| 782 | for (s = 0; s <= (int)maxSymbolValue; ++s) { |
| 783 | bad |= (count[s] != 0) & (HUF_getNbBits(ct[s]) == 0); |
| 784 | } |
| 785 | return !bad; |
| 786 | } |
| 787 | |
| 788 | size_t HUF_compressBound(size_t size) { return HUF_COMPRESSBOUND(size); } |
| 789 | |
| 790 | /** HUF_CStream_t: |
| 791 | * Huffman uses its own BIT_CStream_t implementation. |
| 792 | * There are three major differences from BIT_CStream_t: |
| 793 | * 1. HUF_addBits() takes a HUF_CElt (size_t) which is |
| 794 | * the pair (nbBits, value) in the format: |
| 795 | * format: |
| 796 | * - Bits [0, 4) = nbBits |
| 797 | * - Bits [4, 64 - nbBits) = 0 |
| 798 | * - Bits [64 - nbBits, 64) = value |
| 799 | * 2. The bitContainer is built from the upper bits and |
| 800 | * right shifted. E.g. to add a new value of N bits |
| 801 | * you right shift the bitContainer by N, then or in |
| 802 | * the new value into the N upper bits. |
| 803 | * 3. The bitstream has two bit containers. You can add |
| 804 | * bits to the second container and merge them into |
| 805 | * the first container. |
| 806 | */ |
| 807 | |
| 808 | #define HUF_BITS_IN_CONTAINER (sizeof(size_t) * 8) |
| 809 | |
| 810 | typedef struct { |
| 811 | size_t bitContainer[2]; |
| 812 | size_t bitPos[2]; |
| 813 | |
| 814 | BYTE* startPtr; |
| 815 | BYTE* ptr; |
| 816 | BYTE* endPtr; |
| 817 | } HUF_CStream_t; |
| 818 | |
| 819 | /**! HUF_initCStream(): |
| 820 | * Initializes the bitstream. |
| 821 | * @returns 0 or an error code. |
| 822 | */ |
| 823 | static size_t HUF_initCStream(HUF_CStream_t* bitC, |
| 824 | void* startPtr, size_t dstCapacity) |
| 825 | { |
| 826 | ZSTD_memset(bitC, 0, sizeof(*bitC)); |
| 827 | bitC->startPtr = (BYTE*)startPtr; |
| 828 | bitC->ptr = bitC->startPtr; |
| 829 | bitC->endPtr = bitC->startPtr + dstCapacity - sizeof(bitC->bitContainer[0]); |
| 830 | if (dstCapacity <= sizeof(bitC->bitContainer[0])) return ERROR(dstSize_tooSmall); |
| 831 | return 0; |
| 832 | } |
| 833 | |
| 834 | /*! HUF_addBits(): |
| 835 | * Adds the symbol stored in HUF_CElt elt to the bitstream. |
| 836 | * |
| 837 | * @param elt The element we're adding. This is a (nbBits, value) pair. |
| 838 | * See the HUF_CStream_t docs for the format. |
| 839 | * @param idx Insert into the bitstream at this idx. |
| 840 | * @param kFast This is a template parameter. If the bitstream is guaranteed |
| 841 | * to have at least 4 unused bits after this call it may be 1, |
| 842 | * otherwise it must be 0. HUF_addBits() is faster when fast is set. |
| 843 | */ |
| 844 | FORCE_INLINE_TEMPLATE void HUF_addBits(HUF_CStream_t* bitC, HUF_CElt elt, int idx, int kFast) |
| 845 | { |
| 846 | assert(idx <= 1); |
| 847 | assert(HUF_getNbBits(elt) <= HUF_TABLELOG_ABSOLUTEMAX); |
| 848 | /* This is efficient on x86-64 with BMI2 because shrx |
| 849 | * only reads the low 6 bits of the register. The compiler |
| 850 | * knows this and elides the mask. When fast is set, |
| 851 | * every operation can use the same value loaded from elt. |
| 852 | */ |
| 853 | bitC->bitContainer[idx] >>= HUF_getNbBits(elt); |
| 854 | bitC->bitContainer[idx] |= kFast ? HUF_getValueFast(elt) : HUF_getValue(elt); |
| 855 | /* We only read the low 8 bits of bitC->bitPos[idx] so it |
| 856 | * doesn't matter that the high bits have noise from the value. |
| 857 | */ |
| 858 | bitC->bitPos[idx] += HUF_getNbBitsFast(elt); |
| 859 | assert((bitC->bitPos[idx] & 0xFF) <= HUF_BITS_IN_CONTAINER); |
| 860 | /* The last 4-bits of elt are dirty if fast is set, |
| 861 | * so we must not be overwriting bits that have already been |
| 862 | * inserted into the bit container. |
| 863 | */ |
| 864 | #if DEBUGLEVEL >= 1 |
| 865 | { |
| 866 | size_t const nbBits = HUF_getNbBits(elt); |
| 867 | size_t const dirtyBits = nbBits == 0 ? 0 : ZSTD_highbit32((U32)nbBits) + 1; |
| 868 | (void)dirtyBits; |
| 869 | /* Middle bits are 0. */ |
| 870 | assert(((elt >> dirtyBits) << (dirtyBits + nbBits)) == 0); |
| 871 | /* We didn't overwrite any bits in the bit container. */ |
| 872 | assert(!kFast || (bitC->bitPos[idx] & 0xFF) <= HUF_BITS_IN_CONTAINER); |
| 873 | (void)dirtyBits; |
| 874 | } |
| 875 | #endif |
| 876 | } |
| 877 | |
| 878 | FORCE_INLINE_TEMPLATE void HUF_zeroIndex1(HUF_CStream_t* bitC) |
| 879 | { |
| 880 | bitC->bitContainer[1] = 0; |
| 881 | bitC->bitPos[1] = 0; |
| 882 | } |
| 883 | |
| 884 | /*! HUF_mergeIndex1() : |
| 885 | * Merges the bit container @ index 1 into the bit container @ index 0 |
| 886 | * and zeros the bit container @ index 1. |
| 887 | */ |
| 888 | FORCE_INLINE_TEMPLATE void HUF_mergeIndex1(HUF_CStream_t* bitC) |
| 889 | { |
| 890 | assert((bitC->bitPos[1] & 0xFF) < HUF_BITS_IN_CONTAINER); |
| 891 | bitC->bitContainer[0] >>= (bitC->bitPos[1] & 0xFF); |
| 892 | bitC->bitContainer[0] |= bitC->bitContainer[1]; |
| 893 | bitC->bitPos[0] += bitC->bitPos[1]; |
| 894 | assert((bitC->bitPos[0] & 0xFF) <= HUF_BITS_IN_CONTAINER); |
| 895 | } |
| 896 | |
| 897 | /*! HUF_flushBits() : |
| 898 | * Flushes the bits in the bit container @ index 0. |
| 899 | * |
| 900 | * @post bitPos will be < 8. |
| 901 | * @param kFast If kFast is set then we must know a-priori that |
| 902 | * the bit container will not overflow. |
| 903 | */ |
| 904 | FORCE_INLINE_TEMPLATE void HUF_flushBits(HUF_CStream_t* bitC, int kFast) |
| 905 | { |
| 906 | /* The upper bits of bitPos are noisy, so we must mask by 0xFF. */ |
| 907 | size_t const nbBits = bitC->bitPos[0] & 0xFF; |
| 908 | size_t const nbBytes = nbBits >> 3; |
| 909 | /* The top nbBits bits of bitContainer are the ones we need. */ |
| 910 | size_t const bitContainer = bitC->bitContainer[0] >> (HUF_BITS_IN_CONTAINER - nbBits); |
| 911 | /* Mask bitPos to account for the bytes we consumed. */ |
| 912 | bitC->bitPos[0] &= 7; |
| 913 | assert(nbBits > 0); |
| 914 | assert(nbBits <= sizeof(bitC->bitContainer[0]) * 8); |
| 915 | assert(bitC->ptr <= bitC->endPtr); |
| 916 | MEM_writeLEST(bitC->ptr, bitContainer); |
| 917 | bitC->ptr += nbBytes; |
| 918 | assert(!kFast || bitC->ptr <= bitC->endPtr); |
| 919 | if (!kFast && bitC->ptr > bitC->endPtr) bitC->ptr = bitC->endPtr; |
| 920 | /* bitContainer doesn't need to be modified because the leftover |
| 921 | * bits are already the top bitPos bits. And we don't care about |
| 922 | * noise in the lower values. |
| 923 | */ |
| 924 | } |
| 925 | |
| 926 | /*! HUF_endMark() |
| 927 | * @returns The Huffman stream end mark: A 1-bit value = 1. |
| 928 | */ |
| 929 | static HUF_CElt HUF_endMark(void) |
| 930 | { |
| 931 | HUF_CElt endMark; |
| 932 | HUF_setNbBits(&endMark, 1); |
| 933 | HUF_setValue(&endMark, 1); |
| 934 | return endMark; |
| 935 | } |
| 936 | |
| 937 | /*! HUF_closeCStream() : |
| 938 | * @return Size of CStream, in bytes, |
| 939 | * or 0 if it could not fit into dstBuffer */ |
| 940 | static size_t HUF_closeCStream(HUF_CStream_t* bitC) |
| 941 | { |
| 942 | HUF_addBits(bitC, HUF_endMark(), /* idx */ 0, /* kFast */ 0); |
| 943 | HUF_flushBits(bitC, /* kFast */ 0); |
| 944 | { |
| 945 | size_t const nbBits = bitC->bitPos[0] & 0xFF; |
| 946 | if (bitC->ptr >= bitC->endPtr) return 0; /* overflow detected */ |
| 947 | return (size_t)(bitC->ptr - bitC->startPtr) + (nbBits > 0); |
| 948 | } |
| 949 | } |
| 950 | |
| 951 | FORCE_INLINE_TEMPLATE void |
| 952 | HUF_encodeSymbol(HUF_CStream_t* bitCPtr, U32 symbol, const HUF_CElt* CTable, int idx, int fast) |
| 953 | { |
| 954 | HUF_addBits(bitCPtr, CTable[symbol], idx, fast); |
| 955 | } |
| 956 | |
| 957 | FORCE_INLINE_TEMPLATE void |
| 958 | HUF_compress1X_usingCTable_internal_body_loop(HUF_CStream_t* bitC, |
| 959 | const BYTE* ip, size_t srcSize, |
| 960 | const HUF_CElt* ct, |
| 961 | int kUnroll, int kFastFlush, int kLastFast) |
| 962 | { |
| 963 | /* Join to kUnroll */ |
| 964 | int n = (int)srcSize; |
| 965 | int rem = n % kUnroll; |
| 966 | if (rem > 0) { |
| 967 | for (; rem > 0; --rem) { |
| 968 | HUF_encodeSymbol(bitC, ip[--n], ct, 0, /* fast */ 0); |
| 969 | } |
| 970 | HUF_flushBits(bitC, kFastFlush); |
| 971 | } |
| 972 | assert(n % kUnroll == 0); |
| 973 | |
| 974 | /* Join to 2 * kUnroll */ |
| 975 | if (n % (2 * kUnroll)) { |
| 976 | int u; |
| 977 | for (u = 1; u < kUnroll; ++u) { |
| 978 | HUF_encodeSymbol(bitC, ip[n - u], ct, 0, 1); |
| 979 | } |
| 980 | HUF_encodeSymbol(bitC, ip[n - kUnroll], ct, 0, kLastFast); |
| 981 | HUF_flushBits(bitC, kFastFlush); |
| 982 | n -= kUnroll; |
| 983 | } |
| 984 | assert(n % (2 * kUnroll) == 0); |
| 985 | |
| 986 | for (; n>0; n-= 2 * kUnroll) { |
| 987 | /* Encode kUnroll symbols into the bitstream @ index 0. */ |
| 988 | int u; |
| 989 | for (u = 1; u < kUnroll; ++u) { |
| 990 | HUF_encodeSymbol(bitC, ip[n - u], ct, /* idx */ 0, /* fast */ 1); |
| 991 | } |
| 992 | HUF_encodeSymbol(bitC, ip[n - kUnroll], ct, /* idx */ 0, /* fast */ kLastFast); |
| 993 | HUF_flushBits(bitC, kFastFlush); |
| 994 | /* Encode kUnroll symbols into the bitstream @ index 1. |
| 995 | * This allows us to start filling the bit container |
| 996 | * without any data dependencies. |
| 997 | */ |
| 998 | HUF_zeroIndex1(bitC); |
| 999 | for (u = 1; u < kUnroll; ++u) { |
| 1000 | HUF_encodeSymbol(bitC, ip[n - kUnroll - u], ct, /* idx */ 1, /* fast */ 1); |
| 1001 | } |
| 1002 | HUF_encodeSymbol(bitC, ip[n - kUnroll - kUnroll], ct, /* idx */ 1, /* fast */ kLastFast); |
| 1003 | /* Merge bitstream @ index 1 into the bitstream @ index 0 */ |
| 1004 | HUF_mergeIndex1(bitC); |
| 1005 | HUF_flushBits(bitC, kFastFlush); |
| 1006 | } |
| 1007 | assert(n == 0); |
| 1008 | |
| 1009 | } |
| 1010 | |
| 1011 | /** |
| 1012 | * Returns a tight upper bound on the output space needed by Huffman |
| 1013 | * with 8 bytes buffer to handle over-writes. If the output is at least |
| 1014 | * this large we don't need to do bounds checks during Huffman encoding. |
| 1015 | */ |
| 1016 | static size_t HUF_tightCompressBound(size_t srcSize, size_t tableLog) |
| 1017 | { |
| 1018 | return ((srcSize * tableLog) >> 3) + 8; |
| 1019 | } |
| 1020 | |
| 1021 | |
| 1022 | FORCE_INLINE_TEMPLATE size_t |
| 1023 | HUF_compress1X_usingCTable_internal_body(void* dst, size_t dstSize, |
| 1024 | const void* src, size_t srcSize, |
| 1025 | const HUF_CElt* CTable) |
| 1026 | { |
| 1027 | U32 const tableLog = (U32)CTable[0]; |
| 1028 | HUF_CElt const* ct = CTable + 1; |
| 1029 | const BYTE* ip = (const BYTE*) src; |
| 1030 | BYTE* const ostart = (BYTE*)dst; |
| 1031 | BYTE* const oend = ostart + dstSize; |
| 1032 | BYTE* op = ostart; |
| 1033 | HUF_CStream_t bitC; |
| 1034 | |
| 1035 | /* init */ |
| 1036 | if (dstSize < 8) return 0; /* not enough space to compress */ |
| 1037 | { size_t const initErr = HUF_initCStream(&bitC, op, (size_t)(oend-op)); |
| 1038 | if (HUF_isError(initErr)) return 0; } |
| 1039 | |
| 1040 | if (dstSize < HUF_tightCompressBound(srcSize, (size_t)tableLog) || tableLog > 11) |
| 1041 | HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ MEM_32bits() ? 2 : 4, /* kFast */ 0, /* kLastFast */ 0); |
| 1042 | else { |
| 1043 | if (MEM_32bits()) { |
| 1044 | switch (tableLog) { |
| 1045 | case 11: |
| 1046 | HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 2, /* kFastFlush */ 1, /* kLastFast */ 0); |
| 1047 | break; |
| 1048 | case 10: ZSTD_FALLTHROUGH; |
| 1049 | case 9: ZSTD_FALLTHROUGH; |
| 1050 | case 8: |
| 1051 | HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 2, /* kFastFlush */ 1, /* kLastFast */ 1); |
| 1052 | break; |
| 1053 | case 7: ZSTD_FALLTHROUGH; |
| 1054 | default: |
| 1055 | HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 3, /* kFastFlush */ 1, /* kLastFast */ 1); |
| 1056 | break; |
| 1057 | } |
| 1058 | } else { |
| 1059 | switch (tableLog) { |
| 1060 | case 11: |
| 1061 | HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 5, /* kFastFlush */ 1, /* kLastFast */ 0); |
| 1062 | break; |
| 1063 | case 10: |
| 1064 | HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 5, /* kFastFlush */ 1, /* kLastFast */ 1); |
| 1065 | break; |
| 1066 | case 9: |
| 1067 | HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 6, /* kFastFlush */ 1, /* kLastFast */ 0); |
| 1068 | break; |
| 1069 | case 8: |
| 1070 | HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 7, /* kFastFlush */ 1, /* kLastFast */ 0); |
| 1071 | break; |
| 1072 | case 7: |
| 1073 | HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 8, /* kFastFlush */ 1, /* kLastFast */ 0); |
| 1074 | break; |
| 1075 | case 6: ZSTD_FALLTHROUGH; |
| 1076 | default: |
| 1077 | HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 9, /* kFastFlush */ 1, /* kLastFast */ 1); |
| 1078 | break; |
| 1079 | } |
| 1080 | } |
| 1081 | } |
| 1082 | assert(bitC.ptr <= bitC.endPtr); |
| 1083 | |
| 1084 | return HUF_closeCStream(&bitC); |
| 1085 | } |
| 1086 | |
| 1087 | #if DYNAMIC_BMI2 |
| 1088 | |
| 1089 | static BMI2_TARGET_ATTRIBUTE size_t |
| 1090 | HUF_compress1X_usingCTable_internal_bmi2(void* dst, size_t dstSize, |
| 1091 | const void* src, size_t srcSize, |
| 1092 | const HUF_CElt* CTable) |
| 1093 | { |
| 1094 | return HUF_compress1X_usingCTable_internal_body(dst, dstSize, src, srcSize, CTable); |
| 1095 | } |
| 1096 | |
| 1097 | static size_t |
| 1098 | HUF_compress1X_usingCTable_internal_default(void* dst, size_t dstSize, |
| 1099 | const void* src, size_t srcSize, |
| 1100 | const HUF_CElt* CTable) |
| 1101 | { |
| 1102 | return HUF_compress1X_usingCTable_internal_body(dst, dstSize, src, srcSize, CTable); |
| 1103 | } |
| 1104 | |
| 1105 | static size_t |
| 1106 | HUF_compress1X_usingCTable_internal(void* dst, size_t dstSize, |
| 1107 | const void* src, size_t srcSize, |
| 1108 | const HUF_CElt* CTable, const int flags) |
| 1109 | { |
| 1110 | if (flags & HUF_flags_bmi2) { |
| 1111 | return HUF_compress1X_usingCTable_internal_bmi2(dst, dstSize, src, srcSize, CTable); |
| 1112 | } |
| 1113 | return HUF_compress1X_usingCTable_internal_default(dst, dstSize, src, srcSize, CTable); |
| 1114 | } |
| 1115 | |
| 1116 | #else |
| 1117 | |
| 1118 | static size_t |
| 1119 | HUF_compress1X_usingCTable_internal(void* dst, size_t dstSize, |
| 1120 | const void* src, size_t srcSize, |
| 1121 | const HUF_CElt* CTable, const int flags) |
| 1122 | { |
| 1123 | (void)flags; |
| 1124 | return HUF_compress1X_usingCTable_internal_body(dst, dstSize, src, srcSize, CTable); |
| 1125 | } |
| 1126 | |
| 1127 | #endif |
| 1128 | |
| 1129 | size_t HUF_compress1X_usingCTable(void* dst, size_t dstSize, const void* src, size_t srcSize, const HUF_CElt* CTable, int flags) |
| 1130 | { |
| 1131 | return HUF_compress1X_usingCTable_internal(dst, dstSize, src, srcSize, CTable, flags); |
| 1132 | } |
| 1133 | |
| 1134 | static size_t |
| 1135 | HUF_compress4X_usingCTable_internal(void* dst, size_t dstSize, |
| 1136 | const void* src, size_t srcSize, |
| 1137 | const HUF_CElt* CTable, int flags) |
| 1138 | { |
| 1139 | size_t const segmentSize = (srcSize+3)/4; /* first 3 segments */ |
| 1140 | const BYTE* ip = (const BYTE*) src; |
| 1141 | const BYTE* const iend = ip + srcSize; |
| 1142 | BYTE* const ostart = (BYTE*) dst; |
| 1143 | BYTE* const oend = ostart + dstSize; |
| 1144 | BYTE* op = ostart; |
| 1145 | |
| 1146 | if (dstSize < 6 + 1 + 1 + 1 + 8) return 0; /* minimum space to compress successfully */ |
| 1147 | if (srcSize < 12) return 0; /* no saving possible : too small input */ |
| 1148 | op += 6; /* jumpTable */ |
| 1149 | |
| 1150 | assert(op <= oend); |
| 1151 | { CHECK_V_F(cSize, HUF_compress1X_usingCTable_internal(op, (size_t)(oend-op), ip, segmentSize, CTable, flags) ); |
| 1152 | if (cSize == 0 || cSize > 65535) return 0; |
| 1153 | MEM_writeLE16(ostart, (U16)cSize); |
| 1154 | op += cSize; |
| 1155 | } |
| 1156 | |
| 1157 | ip += segmentSize; |
| 1158 | assert(op <= oend); |
| 1159 | { CHECK_V_F(cSize, HUF_compress1X_usingCTable_internal(op, (size_t)(oend-op), ip, segmentSize, CTable, flags) ); |
| 1160 | if (cSize == 0 || cSize > 65535) return 0; |
| 1161 | MEM_writeLE16(ostart+2, (U16)cSize); |
| 1162 | op += cSize; |
| 1163 | } |
| 1164 | |
| 1165 | ip += segmentSize; |
| 1166 | assert(op <= oend); |
| 1167 | { CHECK_V_F(cSize, HUF_compress1X_usingCTable_internal(op, (size_t)(oend-op), ip, segmentSize, CTable, flags) ); |
| 1168 | if (cSize == 0 || cSize > 65535) return 0; |
| 1169 | MEM_writeLE16(ostart+4, (U16)cSize); |
| 1170 | op += cSize; |
| 1171 | } |
| 1172 | |
| 1173 | ip += segmentSize; |
| 1174 | assert(op <= oend); |
| 1175 | assert(ip <= iend); |
| 1176 | { CHECK_V_F(cSize, HUF_compress1X_usingCTable_internal(op, (size_t)(oend-op), ip, (size_t)(iend-ip), CTable, flags) ); |
| 1177 | if (cSize == 0 || cSize > 65535) return 0; |
| 1178 | op += cSize; |
| 1179 | } |
| 1180 | |
| 1181 | return (size_t)(op-ostart); |
| 1182 | } |
| 1183 | |
| 1184 | size_t HUF_compress4X_usingCTable(void* dst, size_t dstSize, const void* src, size_t srcSize, const HUF_CElt* CTable, int flags) |
| 1185 | { |
| 1186 | return HUF_compress4X_usingCTable_internal(dst, dstSize, src, srcSize, CTable, flags); |
| 1187 | } |
| 1188 | |
| 1189 | typedef enum { HUF_singleStream, HUF_fourStreams } HUF_nbStreams_e; |
| 1190 | |
| 1191 | static size_t HUF_compressCTable_internal( |
| 1192 | BYTE* const ostart, BYTE* op, BYTE* const oend, |
| 1193 | const void* src, size_t srcSize, |
| 1194 | HUF_nbStreams_e nbStreams, const HUF_CElt* CTable, const int flags) |
| 1195 | { |
| 1196 | size_t const cSize = (nbStreams==HUF_singleStream) ? |
| 1197 | HUF_compress1X_usingCTable_internal(op, (size_t)(oend - op), src, srcSize, CTable, flags) : |
| 1198 | HUF_compress4X_usingCTable_internal(op, (size_t)(oend - op), src, srcSize, CTable, flags); |
| 1199 | if (HUF_isError(cSize)) { return cSize; } |
| 1200 | if (cSize==0) { return 0; } /* uncompressible */ |
| 1201 | op += cSize; |
| 1202 | /* check compressibility */ |
| 1203 | assert(op >= ostart); |
| 1204 | if ((size_t)(op-ostart) >= srcSize-1) { return 0; } |
| 1205 | return (size_t)(op-ostart); |
| 1206 | } |
| 1207 | |
| 1208 | typedef struct { |
| 1209 | unsigned count[HUF_SYMBOLVALUE_MAX + 1]; |
| 1210 | HUF_CElt CTable[HUF_CTABLE_SIZE_ST(HUF_SYMBOLVALUE_MAX)]; |
| 1211 | union { |
| 1212 | HUF_buildCTable_wksp_tables buildCTable_wksp; |
| 1213 | HUF_WriteCTableWksp writeCTable_wksp; |
| 1214 | U32 hist_wksp[HIST_WKSP_SIZE_U32]; |
| 1215 | } wksps; |
| 1216 | } HUF_compress_tables_t; |
| 1217 | |
| 1218 | #define SUSPECT_INCOMPRESSIBLE_SAMPLE_SIZE 4096 |
| 1219 | #define SUSPECT_INCOMPRESSIBLE_SAMPLE_RATIO 10 /* Must be >= 2 */ |
| 1220 | |
| 1221 | unsigned HUF_cardinality(const unsigned* count, unsigned maxSymbolValue) |
| 1222 | { |
| 1223 | unsigned cardinality = 0; |
| 1224 | unsigned i; |
| 1225 | |
| 1226 | for (i = 0; i < maxSymbolValue + 1; i++) { |
| 1227 | if (count[i] != 0) cardinality += 1; |
| 1228 | } |
| 1229 | |
| 1230 | return cardinality; |
| 1231 | } |
| 1232 | |
| 1233 | unsigned HUF_minTableLog(unsigned symbolCardinality) |
| 1234 | { |
| 1235 | U32 minBitsSymbols = ZSTD_highbit32(symbolCardinality) + 1; |
| 1236 | return minBitsSymbols; |
| 1237 | } |
| 1238 | |
| 1239 | unsigned HUF_optimalTableLog( |
| 1240 | unsigned maxTableLog, |
| 1241 | size_t srcSize, |
| 1242 | unsigned maxSymbolValue, |
| 1243 | void* workSpace, size_t wkspSize, |
| 1244 | HUF_CElt* table, |
| 1245 | const unsigned* count, |
| 1246 | int flags) |
| 1247 | { |
| 1248 | assert(srcSize > 1); /* Not supported, RLE should be used instead */ |
| 1249 | assert(wkspSize >= sizeof(HUF_buildCTable_wksp_tables)); |
| 1250 | |
| 1251 | if (!(flags & HUF_flags_optimalDepth)) { |
| 1252 | /* cheap evaluation, based on FSE */ |
| 1253 | return FSE_optimalTableLog_internal(maxTableLog, srcSize, maxSymbolValue, 1); |
| 1254 | } |
| 1255 | |
| 1256 | { BYTE* dst = (BYTE*)workSpace + sizeof(HUF_WriteCTableWksp); |
| 1257 | size_t dstSize = wkspSize - sizeof(HUF_WriteCTableWksp); |
| 1258 | size_t maxBits, hSize, newSize; |
| 1259 | const unsigned symbolCardinality = HUF_cardinality(count, maxSymbolValue); |
| 1260 | const unsigned minTableLog = HUF_minTableLog(symbolCardinality); |
| 1261 | size_t optSize = ((size_t) ~0) - 1; |
| 1262 | unsigned optLog = maxTableLog, optLogGuess; |
| 1263 | |
| 1264 | DEBUGLOG(6, "HUF_optimalTableLog: probing huf depth (srcSize=%zu)", srcSize); |
| 1265 | |
| 1266 | /* Search until size increases */ |
| 1267 | for (optLogGuess = minTableLog; optLogGuess <= maxTableLog; optLogGuess++) { |
| 1268 | DEBUGLOG(7, "checking for huffLog=%u", optLogGuess); |
| 1269 | maxBits = HUF_buildCTable_wksp(table, count, maxSymbolValue, optLogGuess, workSpace, wkspSize); |
| 1270 | if (ERR_isError(maxBits)) continue; |
| 1271 | |
| 1272 | if (maxBits < optLogGuess && optLogGuess > minTableLog) break; |
| 1273 | |
| 1274 | hSize = HUF_writeCTable_wksp(dst, dstSize, table, maxSymbolValue, (U32)maxBits, workSpace, wkspSize); |
| 1275 | |
| 1276 | if (ERR_isError(hSize)) continue; |
| 1277 | |
| 1278 | newSize = HUF_estimateCompressedSize(table, count, maxSymbolValue) + hSize; |
| 1279 | |
| 1280 | if (newSize > optSize + 1) { |
| 1281 | break; |
| 1282 | } |
| 1283 | |
| 1284 | if (newSize < optSize) { |
| 1285 | optSize = newSize; |
| 1286 | optLog = optLogGuess; |
| 1287 | } |
| 1288 | } |
| 1289 | assert(optLog <= HUF_TABLELOG_MAX); |
| 1290 | return optLog; |
| 1291 | } |
| 1292 | } |
| 1293 | |
| 1294 | /* HUF_compress_internal() : |
| 1295 | * `workSpace_align4` must be aligned on 4-bytes boundaries, |
| 1296 | * and occupies the same space as a table of HUF_WORKSPACE_SIZE_U64 unsigned */ |
| 1297 | static size_t |
| 1298 | HUF_compress_internal (void* dst, size_t dstSize, |
| 1299 | const void* src, size_t srcSize, |
| 1300 | unsigned maxSymbolValue, unsigned huffLog, |
| 1301 | HUF_nbStreams_e nbStreams, |
| 1302 | void* workSpace, size_t wkspSize, |
| 1303 | HUF_CElt* oldHufTable, HUF_repeat* repeat, int flags) |
| 1304 | { |
| 1305 | HUF_compress_tables_t* const table = (HUF_compress_tables_t*)HUF_alignUpWorkspace(workSpace, &wkspSize, ZSTD_ALIGNOF(size_t)); |
| 1306 | BYTE* const ostart = (BYTE*)dst; |
| 1307 | BYTE* const oend = ostart + dstSize; |
| 1308 | BYTE* op = ostart; |
| 1309 | |
| 1310 | DEBUGLOG(5, "HUF_compress_internal (srcSize=%zu)", srcSize); |
| 1311 | HUF_STATIC_ASSERT(sizeof(*table) + HUF_WORKSPACE_MAX_ALIGNMENT <= HUF_WORKSPACE_SIZE); |
| 1312 | |
| 1313 | /* checks & inits */ |
| 1314 | if (wkspSize < sizeof(*table)) return ERROR(workSpace_tooSmall); |
| 1315 | if (!srcSize) return 0; /* Uncompressed */ |
| 1316 | if (!dstSize) return 0; /* cannot fit anything within dst budget */ |
| 1317 | if (srcSize > HUF_BLOCKSIZE_MAX) return ERROR(srcSize_wrong); /* current block size limit */ |
| 1318 | if (huffLog > HUF_TABLELOG_MAX) return ERROR(tableLog_tooLarge); |
| 1319 | if (maxSymbolValue > HUF_SYMBOLVALUE_MAX) return ERROR(maxSymbolValue_tooLarge); |
| 1320 | if (!maxSymbolValue) maxSymbolValue = HUF_SYMBOLVALUE_MAX; |
| 1321 | if (!huffLog) huffLog = HUF_TABLELOG_DEFAULT; |
| 1322 | |
| 1323 | /* Heuristic : If old table is valid, use it for small inputs */ |
| 1324 | if ((flags & HUF_flags_preferRepeat) && repeat && *repeat == HUF_repeat_valid) { |
| 1325 | return HUF_compressCTable_internal(ostart, op, oend, |
| 1326 | src, srcSize, |
| 1327 | nbStreams, oldHufTable, flags); |
| 1328 | } |
| 1329 | |
| 1330 | /* If uncompressible data is suspected, do a smaller sampling first */ |
| 1331 | DEBUG_STATIC_ASSERT(SUSPECT_INCOMPRESSIBLE_SAMPLE_RATIO >= 2); |
| 1332 | if ((flags & HUF_flags_suspectUncompressible) && srcSize >= (SUSPECT_INCOMPRESSIBLE_SAMPLE_SIZE * SUSPECT_INCOMPRESSIBLE_SAMPLE_RATIO)) { |
| 1333 | size_t largestTotal = 0; |
| 1334 | DEBUGLOG(5, "input suspected incompressible : sampling to check"); |
| 1335 | { unsigned maxSymbolValueBegin = maxSymbolValue; |
| 1336 | CHECK_V_F(largestBegin, HIST_count_simple (table->count, &maxSymbolValueBegin, (const BYTE*)src, SUSPECT_INCOMPRESSIBLE_SAMPLE_SIZE) ); |
| 1337 | largestTotal += largestBegin; |
| 1338 | } |
| 1339 | { unsigned maxSymbolValueEnd = maxSymbolValue; |
| 1340 | CHECK_V_F(largestEnd, HIST_count_simple (table->count, &maxSymbolValueEnd, (const BYTE*)src + srcSize - SUSPECT_INCOMPRESSIBLE_SAMPLE_SIZE, SUSPECT_INCOMPRESSIBLE_SAMPLE_SIZE) ); |
| 1341 | largestTotal += largestEnd; |
| 1342 | } |
| 1343 | if (largestTotal <= ((2 * SUSPECT_INCOMPRESSIBLE_SAMPLE_SIZE) >> 7)+4) return 0; /* heuristic : probably not compressible enough */ |
| 1344 | } |
| 1345 | |
| 1346 | /* Scan input and build symbol stats */ |
| 1347 | { CHECK_V_F(largest, HIST_count_wksp (table->count, &maxSymbolValue, (const BYTE*)src, srcSize, table->wksps.hist_wksp, sizeof(table->wksps.hist_wksp)) ); |
| 1348 | if (largest == srcSize) { *ostart = ((const BYTE*)src)[0]; return 1; } /* single symbol, rle */ |
| 1349 | if (largest <= (srcSize >> 7)+4) return 0; /* heuristic : probably not compressible enough */ |
| 1350 | } |
| 1351 | DEBUGLOG(6, "histogram detail completed (%zu symbols)", showU32(table->count, maxSymbolValue+1)); |
| 1352 | |
| 1353 | /* Check validity of previous table */ |
| 1354 | if ( repeat |
| 1355 | && *repeat == HUF_repeat_check |
| 1356 | && !HUF_validateCTable(oldHufTable, table->count, maxSymbolValue)) { |
| 1357 | *repeat = HUF_repeat_none; |
| 1358 | } |
| 1359 | /* Heuristic : use existing table for small inputs */ |
| 1360 | if ((flags & HUF_flags_preferRepeat) && repeat && *repeat != HUF_repeat_none) { |
| 1361 | return HUF_compressCTable_internal(ostart, op, oend, |
| 1362 | src, srcSize, |
| 1363 | nbStreams, oldHufTable, flags); |
| 1364 | } |
| 1365 | |
| 1366 | /* Build Huffman Tree */ |
| 1367 | huffLog = HUF_optimalTableLog(huffLog, srcSize, maxSymbolValue, &table->wksps, sizeof(table->wksps), table->CTable, table->count, flags); |
| 1368 | { size_t const maxBits = HUF_buildCTable_wksp(table->CTable, table->count, |
| 1369 | maxSymbolValue, huffLog, |
| 1370 | &table->wksps.buildCTable_wksp, sizeof(table->wksps.buildCTable_wksp)); |
| 1371 | CHECK_F(maxBits); |
| 1372 | huffLog = (U32)maxBits; |
| 1373 | DEBUGLOG(6, "bit distribution completed (%zu symbols)", showCTableBits(table->CTable + 1, maxSymbolValue+1)); |
| 1374 | } |
| 1375 | /* Zero unused symbols in CTable, so we can check it for validity */ |
| 1376 | { |
| 1377 | size_t const ctableSize = HUF_CTABLE_SIZE_ST(maxSymbolValue); |
| 1378 | size_t const unusedSize = sizeof(table->CTable) - ctableSize * sizeof(HUF_CElt); |
| 1379 | ZSTD_memset(table->CTable + ctableSize, 0, unusedSize); |
| 1380 | } |
| 1381 | |
| 1382 | /* Write table description header */ |
| 1383 | { CHECK_V_F(hSize, HUF_writeCTable_wksp(op, dstSize, table->CTable, maxSymbolValue, huffLog, |
| 1384 | &table->wksps.writeCTable_wksp, sizeof(table->wksps.writeCTable_wksp)) ); |
| 1385 | /* Check if using previous huffman table is beneficial */ |
| 1386 | if (repeat && *repeat != HUF_repeat_none) { |
| 1387 | size_t const oldSize = HUF_estimateCompressedSize(oldHufTable, table->count, maxSymbolValue); |
| 1388 | size_t const newSize = HUF_estimateCompressedSize(table->CTable, table->count, maxSymbolValue); |
| 1389 | if (oldSize <= hSize + newSize || hSize + 12 >= srcSize) { |
| 1390 | return HUF_compressCTable_internal(ostart, op, oend, |
| 1391 | src, srcSize, |
| 1392 | nbStreams, oldHufTable, flags); |
| 1393 | } } |
| 1394 | |
| 1395 | /* Use the new huffman table */ |
| 1396 | if (hSize + 12ul >= srcSize) { return 0; } |
| 1397 | op += hSize; |
| 1398 | if (repeat) { *repeat = HUF_repeat_none; } |
| 1399 | if (oldHufTable) |
| 1400 | ZSTD_memcpy(oldHufTable, table->CTable, sizeof(table->CTable)); /* Save new table */ |
| 1401 | } |
| 1402 | return HUF_compressCTable_internal(ostart, op, oend, |
| 1403 | src, srcSize, |
| 1404 | nbStreams, table->CTable, flags); |
| 1405 | } |
| 1406 | |
| 1407 | size_t HUF_compress1X_repeat (void* dst, size_t dstSize, |
| 1408 | const void* src, size_t srcSize, |
| 1409 | unsigned maxSymbolValue, unsigned huffLog, |
| 1410 | void* workSpace, size_t wkspSize, |
| 1411 | HUF_CElt* hufTable, HUF_repeat* repeat, int flags) |
| 1412 | { |
| 1413 | DEBUGLOG(5, "HUF_compress1X_repeat (srcSize = %zu)", srcSize); |
| 1414 | return HUF_compress_internal(dst, dstSize, src, srcSize, |
| 1415 | maxSymbolValue, huffLog, HUF_singleStream, |
| 1416 | workSpace, wkspSize, hufTable, |
| 1417 | repeat, flags); |
| 1418 | } |
| 1419 | |
| 1420 | /* HUF_compress4X_repeat(): |
| 1421 | * compress input using 4 streams. |
| 1422 | * consider skipping quickly |
| 1423 | * re-use an existing huffman compression table */ |
| 1424 | size_t HUF_compress4X_repeat (void* dst, size_t dstSize, |
| 1425 | const void* src, size_t srcSize, |
| 1426 | unsigned maxSymbolValue, unsigned huffLog, |
| 1427 | void* workSpace, size_t wkspSize, |
| 1428 | HUF_CElt* hufTable, HUF_repeat* repeat, int flags) |
| 1429 | { |
| 1430 | DEBUGLOG(5, "HUF_compress4X_repeat (srcSize = %zu)", srcSize); |
| 1431 | return HUF_compress_internal(dst, dstSize, src, srcSize, |
| 1432 | maxSymbolValue, huffLog, HUF_fourStreams, |
| 1433 | workSpace, wkspSize, |
| 1434 | hufTable, repeat, flags); |
| 1435 | } |