| // SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause | |
| /* | |
| * Copyright (c) Meta Platforms, Inc. and affiliates. | |
| * All rights reserved. | |
| * | |
| * This source code is licensed under both the BSD-style license (found in the | |
| * LICENSE file in the root directory of this source tree) and the GPLv2 (found | |
| * in the COPYING file in the root directory of this source tree). | |
| * You may select, at your option, one of the above-listed licenses. | |
| */ | |
| /*-************************************* | |
| * Dependencies | |
| ***************************************/ | |
| #include "zstd_compress_sequences.h" | |
| /* | |
| * -log2(x / 256) lookup table for x in [0, 256). | |
| * If x == 0: Return 0 | |
| * Else: Return floor(-log2(x / 256) * 256) | |
| */ | |
| static unsigned const kInverseProbabilityLog256[256] = { | |
| 0, 2048, 1792, 1642, 1536, 1453, 1386, 1329, 1280, 1236, 1197, 1162, | |
| 1130, 1100, 1073, 1047, 1024, 1001, 980, 960, 941, 923, 906, 889, | |
| 874, 859, 844, 830, 817, 804, 791, 779, 768, 756, 745, 734, | |
| 724, 714, 704, 694, 685, 676, 667, 658, 650, 642, 633, 626, | |
| 618, 610, 603, 595, 588, 581, 574, 567, 561, 554, 548, 542, | |
| 535, 529, 523, 517, 512, 506, 500, 495, 489, 484, 478, 473, | |
| 468, 463, 458, 453, 448, 443, 438, 434, 429, 424, 420, 415, | |
| 411, 407, 402, 398, 394, 390, 386, 382, 377, 373, 370, 366, | |
| 362, 358, 354, 350, 347, 343, 339, 336, 332, 329, 325, 322, | |
| 318, 315, 311, 308, 305, 302, 298, 295, 292, 289, 286, 282, | |
| 279, 276, 273, 270, 267, 264, 261, 258, 256, 253, 250, 247, | |
| 244, 241, 239, 236, 233, 230, 228, 225, 222, 220, 217, 215, | |
| 212, 209, 207, 204, 202, 199, 197, 194, 192, 190, 187, 185, | |
| 182, 180, 178, 175, 173, 171, 168, 166, 164, 162, 159, 157, | |
| 155, 153, 151, 149, 146, 144, 142, 140, 138, 136, 134, 132, | |
| 130, 128, 126, 123, 121, 119, 117, 115, 114, 112, 110, 108, | |
| 106, 104, 102, 100, 98, 96, 94, 93, 91, 89, 87, 85, | |
| 83, 82, 80, 78, 76, 74, 73, 71, 69, 67, 66, 64, | |
| 62, 61, 59, 57, 55, 54, 52, 50, 49, 47, 46, 44, | |
| 42, 41, 39, 37, 36, 34, 33, 31, 30, 28, 26, 25, | |
| 23, 22, 20, 19, 17, 16, 14, 13, 11, 10, 8, 7, | |
| 5, 4, 2, 1, | |
| }; | |
| static unsigned ZSTD_getFSEMaxSymbolValue(FSE_CTable const* ctable) { | |
| void const* ptr = ctable; | |
| U16 const* u16ptr = (U16 const*)ptr; | |
| U32 const maxSymbolValue = MEM_read16(u16ptr + 1); | |
| return maxSymbolValue; | |
| } | |
| /* | |
| * Returns true if we should use ncount=-1 else we should | |
| * use ncount=1 for low probability symbols instead. | |
| */ | |
| static unsigned ZSTD_useLowProbCount(size_t const nbSeq) | |
| { | |
| /* Heuristic: This should cover most blocks <= 16K and | |
| * start to fade out after 16K to about 32K depending on | |
| * compressibility. | |
| */ | |
| return nbSeq >= 2048; | |
| } | |
| /* | |
| * Returns the cost in bytes of encoding the normalized count header. | |
| * Returns an error if any of the helper functions return an error. | |
| */ | |
| static size_t ZSTD_NCountCost(unsigned const* count, unsigned const max, | |
| size_t const nbSeq, unsigned const FSELog) | |
| { | |
| BYTE wksp[FSE_NCOUNTBOUND]; | |
| S16 norm[MaxSeq + 1]; | |
| const U32 tableLog = FSE_optimalTableLog(FSELog, nbSeq, max); | |
| FORWARD_IF_ERROR(FSE_normalizeCount(norm, tableLog, count, nbSeq, max, ZSTD_useLowProbCount(nbSeq)), ""); | |
| return FSE_writeNCount(wksp, sizeof(wksp), norm, max, tableLog); | |
| } | |
| /* | |
| * Returns the cost in bits of encoding the distribution described by count | |
| * using the entropy bound. | |
| */ | |
| static size_t ZSTD_entropyCost(unsigned const* count, unsigned const max, size_t const total) | |
| { | |
| unsigned cost = 0; | |
| unsigned s; | |
| assert(total > 0); | |
| for (s = 0; s <= max; ++s) { | |
| unsigned norm = (unsigned)((256 * count[s]) / total); | |
| if (count[s] != 0 && norm == 0) | |
| norm = 1; | |
| assert(count[s] < total); | |
| cost += count[s] * kInverseProbabilityLog256[norm]; | |
| } | |
| return cost >> 8; | |
| } | |
| /* | |
| * Returns the cost in bits of encoding the distribution in count using ctable. | |
| * Returns an error if ctable cannot represent all the symbols in count. | |
| */ | |
| size_t ZSTD_fseBitCost( | |
| FSE_CTable const* ctable, | |
| unsigned const* count, | |
| unsigned const max) | |
| { | |
| unsigned const kAccuracyLog = 8; | |
| size_t cost = 0; | |
| unsigned s; | |
| FSE_CState_t cstate; | |
| FSE_initCState(&cstate, ctable); | |
| if (ZSTD_getFSEMaxSymbolValue(ctable) < max) { | |
| DEBUGLOG(5, "Repeat FSE_CTable has maxSymbolValue %u < %u", | |
| ZSTD_getFSEMaxSymbolValue(ctable), max); | |
| return ERROR(GENERIC); | |
| } | |
| for (s = 0; s <= max; ++s) { | |
| unsigned const tableLog = cstate.stateLog; | |
| unsigned const badCost = (tableLog + 1) << kAccuracyLog; | |
| unsigned const bitCost = FSE_bitCost(cstate.symbolTT, tableLog, s, kAccuracyLog); | |
| if (count[s] == 0) | |
| continue; | |
| if (bitCost >= badCost) { | |
| DEBUGLOG(5, "Repeat FSE_CTable has Prob[%u] == 0", s); | |
| return ERROR(GENERIC); | |
| } | |
| cost += (size_t)count[s] * bitCost; | |
| } | |
| return cost >> kAccuracyLog; | |
| } | |
| /* | |
| * Returns the cost in bits of encoding the distribution in count using the | |
| * table described by norm. The max symbol support by norm is assumed >= max. | |
| * norm must be valid for every symbol with non-zero probability in count. | |
| */ | |
| size_t ZSTD_crossEntropyCost(short const* norm, unsigned accuracyLog, | |
| unsigned const* count, unsigned const max) | |
| { | |
| unsigned const shift = 8 - accuracyLog; | |
| size_t cost = 0; | |
| unsigned s; | |
| assert(accuracyLog <= 8); | |
| for (s = 0; s <= max; ++s) { | |
| unsigned const normAcc = (norm[s] != -1) ? (unsigned)norm[s] : 1; | |
| unsigned const norm256 = normAcc << shift; | |
| assert(norm256 > 0); | |
| assert(norm256 < 256); | |
| cost += count[s] * kInverseProbabilityLog256[norm256]; | |
| } | |
| return cost >> 8; | |
| } | |
| SymbolEncodingType_e | |
| ZSTD_selectEncodingType( | |
| FSE_repeat* repeatMode, unsigned const* count, unsigned const max, | |
| size_t const mostFrequent, size_t nbSeq, unsigned const FSELog, | |
| FSE_CTable const* prevCTable, | |
| short const* defaultNorm, U32 defaultNormLog, | |
| ZSTD_DefaultPolicy_e const isDefaultAllowed, | |
| ZSTD_strategy const strategy) | |
| { | |
| ZSTD_STATIC_ASSERT(ZSTD_defaultDisallowed == 0 && ZSTD_defaultAllowed != 0); | |
| if (mostFrequent == nbSeq) { | |
| *repeatMode = FSE_repeat_none; | |
| if (isDefaultAllowed && nbSeq <= 2) { | |
| /* Prefer set_basic over set_rle when there are 2 or fewer symbols, | |
| * since RLE uses 1 byte, but set_basic uses 5-6 bits per symbol. | |
| * If basic encoding isn't possible, always choose RLE. | |
| */ | |
| DEBUGLOG(5, "Selected set_basic"); | |
| return set_basic; | |
| } | |
| DEBUGLOG(5, "Selected set_rle"); | |
| return set_rle; | |
| } | |
| if (strategy < ZSTD_lazy) { | |
| if (isDefaultAllowed) { | |
| size_t const staticFse_nbSeq_max = 1000; | |
| size_t const mult = 10 - strategy; | |
| size_t const baseLog = 3; | |
| size_t const dynamicFse_nbSeq_min = (((size_t)1 << defaultNormLog) * mult) >> baseLog; /* 28-36 for offset, 56-72 for lengths */ | |
| assert(defaultNormLog >= 5 && defaultNormLog <= 6); /* xx_DEFAULTNORMLOG */ | |
| assert(mult <= 9 && mult >= 7); | |
| if ( (*repeatMode == FSE_repeat_valid) | |
| && (nbSeq < staticFse_nbSeq_max) ) { | |
| DEBUGLOG(5, "Selected set_repeat"); | |
| return set_repeat; | |
| } | |
| if ( (nbSeq < dynamicFse_nbSeq_min) | |
| || (mostFrequent < (nbSeq >> (defaultNormLog-1))) ) { | |
| DEBUGLOG(5, "Selected set_basic"); | |
| /* The format allows default tables to be repeated, but it isn't useful. | |
| * When using simple heuristics to select encoding type, we don't want | |
| * to confuse these tables with dictionaries. When running more careful | |
| * analysis, we don't need to waste time checking both repeating tables | |
| * and default tables. | |
| */ | |
| *repeatMode = FSE_repeat_none; | |
| return set_basic; | |
| } | |
| } | |
| } else { | |
| size_t const basicCost = isDefaultAllowed ? ZSTD_crossEntropyCost(defaultNorm, defaultNormLog, count, max) : ERROR(GENERIC); | |
| size_t const repeatCost = *repeatMode != FSE_repeat_none ? ZSTD_fseBitCost(prevCTable, count, max) : ERROR(GENERIC); | |
| size_t const NCountCost = ZSTD_NCountCost(count, max, nbSeq, FSELog); | |
| size_t const compressedCost = (NCountCost << 3) + ZSTD_entropyCost(count, max, nbSeq); | |
| if (isDefaultAllowed) { | |
| assert(!ZSTD_isError(basicCost)); | |
| assert(!(*repeatMode == FSE_repeat_valid && ZSTD_isError(repeatCost))); | |
| } | |
| assert(!ZSTD_isError(NCountCost)); | |
| assert(compressedCost < ERROR(maxCode)); | |
| DEBUGLOG(5, "Estimated bit costs: basic=%u\trepeat=%u\tcompressed=%u", | |
| (unsigned)basicCost, (unsigned)repeatCost, (unsigned)compressedCost); | |
| if (basicCost <= repeatCost && basicCost <= compressedCost) { | |
| DEBUGLOG(5, "Selected set_basic"); | |
| assert(isDefaultAllowed); | |
| *repeatMode = FSE_repeat_none; | |
| return set_basic; | |
| } | |
| if (repeatCost <= compressedCost) { | |
| DEBUGLOG(5, "Selected set_repeat"); | |
| assert(!ZSTD_isError(repeatCost)); | |
| return set_repeat; | |
| } | |
| assert(compressedCost < basicCost && compressedCost < repeatCost); | |
| } | |
| DEBUGLOG(5, "Selected set_compressed"); | |
| *repeatMode = FSE_repeat_check; | |
| return set_compressed; | |
| } | |
| typedef struct { | |
| S16 norm[MaxSeq + 1]; | |
| U32 wksp[FSE_BUILD_CTABLE_WORKSPACE_SIZE_U32(MaxSeq, MaxFSELog)]; | |
| } ZSTD_BuildCTableWksp; | |
| size_t | |
| ZSTD_buildCTable(void* dst, size_t dstCapacity, | |
| FSE_CTable* nextCTable, U32 FSELog, SymbolEncodingType_e type, | |
| unsigned* count, U32 max, | |
| const BYTE* codeTable, size_t nbSeq, | |
| const S16* defaultNorm, U32 defaultNormLog, U32 defaultMax, | |
| const FSE_CTable* prevCTable, size_t prevCTableSize, | |
| void* entropyWorkspace, size_t entropyWorkspaceSize) | |
| { | |
| BYTE* op = (BYTE*)dst; | |
| const BYTE* const oend = op + dstCapacity; | |
| DEBUGLOG(6, "ZSTD_buildCTable (dstCapacity=%u)", (unsigned)dstCapacity); | |
| switch (type) { | |
| case set_rle: | |
| FORWARD_IF_ERROR(FSE_buildCTable_rle(nextCTable, (BYTE)max), ""); | |
| RETURN_ERROR_IF(dstCapacity==0, dstSize_tooSmall, "not enough space"); | |
| *op = codeTable[0]; | |
| return 1; | |
| case set_repeat: | |
| ZSTD_memcpy(nextCTable, prevCTable, prevCTableSize); | |
| return 0; | |
| case set_basic: | |
| FORWARD_IF_ERROR(FSE_buildCTable_wksp(nextCTable, defaultNorm, defaultMax, defaultNormLog, entropyWorkspace, entropyWorkspaceSize), ""); /* note : could be pre-calculated */ | |
| return 0; | |
| case set_compressed: { | |
| ZSTD_BuildCTableWksp* wksp = (ZSTD_BuildCTableWksp*)entropyWorkspace; | |
| size_t nbSeq_1 = nbSeq; | |
| const U32 tableLog = FSE_optimalTableLog(FSELog, nbSeq, max); | |
| if (count[codeTable[nbSeq-1]] > 1) { | |
| count[codeTable[nbSeq-1]]--; | |
| nbSeq_1--; | |
| } | |
| assert(nbSeq_1 > 1); | |
| assert(entropyWorkspaceSize >= sizeof(ZSTD_BuildCTableWksp)); | |
| (void)entropyWorkspaceSize; | |
| FORWARD_IF_ERROR(FSE_normalizeCount(wksp->norm, tableLog, count, nbSeq_1, max, ZSTD_useLowProbCount(nbSeq_1)), "FSE_normalizeCount failed"); | |
| assert(oend >= op); | |
| { size_t const NCountSize = FSE_writeNCount(op, (size_t)(oend - op), wksp->norm, max, tableLog); /* overflow protected */ | |
| FORWARD_IF_ERROR(NCountSize, "FSE_writeNCount failed"); | |
| FORWARD_IF_ERROR(FSE_buildCTable_wksp(nextCTable, wksp->norm, max, tableLog, wksp->wksp, sizeof(wksp->wksp)), "FSE_buildCTable_wksp failed"); | |
| return NCountSize; | |
| } | |
| } | |
| default: assert(0); RETURN_ERROR(GENERIC, "impossible to reach"); | |
| } | |
| } | |
| FORCE_INLINE_TEMPLATE size_t | |
| ZSTD_encodeSequences_body( | |
| void* dst, size_t dstCapacity, | |
| FSE_CTable const* CTable_MatchLength, BYTE const* mlCodeTable, | |
| FSE_CTable const* CTable_OffsetBits, BYTE const* ofCodeTable, | |
| FSE_CTable const* CTable_LitLength, BYTE const* llCodeTable, | |
| SeqDef const* sequences, size_t nbSeq, int longOffsets) | |
| { | |
| BIT_CStream_t blockStream; | |
| FSE_CState_t stateMatchLength; | |
| FSE_CState_t stateOffsetBits; | |
| FSE_CState_t stateLitLength; | |
| RETURN_ERROR_IF( | |
| ERR_isError(BIT_initCStream(&blockStream, dst, dstCapacity)), | |
| dstSize_tooSmall, "not enough space remaining"); | |
| DEBUGLOG(6, "available space for bitstream : %i (dstCapacity=%u)", | |
| (int)(blockStream.endPtr - blockStream.startPtr), | |
| (unsigned)dstCapacity); | |
| /* first symbols */ | |
| FSE_initCState2(&stateMatchLength, CTable_MatchLength, mlCodeTable[nbSeq-1]); | |
| FSE_initCState2(&stateOffsetBits, CTable_OffsetBits, ofCodeTable[nbSeq-1]); | |
| FSE_initCState2(&stateLitLength, CTable_LitLength, llCodeTable[nbSeq-1]); | |
| BIT_addBits(&blockStream, sequences[nbSeq-1].litLength, LL_bits[llCodeTable[nbSeq-1]]); | |
| if (MEM_32bits()) BIT_flushBits(&blockStream); | |
| BIT_addBits(&blockStream, sequences[nbSeq-1].mlBase, ML_bits[mlCodeTable[nbSeq-1]]); | |
| if (MEM_32bits()) BIT_flushBits(&blockStream); | |
| if (longOffsets) { | |
| U32 const ofBits = ofCodeTable[nbSeq-1]; | |
| unsigned const extraBits = ofBits - MIN(ofBits, STREAM_ACCUMULATOR_MIN-1); | |
| if (extraBits) { | |
| BIT_addBits(&blockStream, sequences[nbSeq-1].offBase, extraBits); | |
| BIT_flushBits(&blockStream); | |
| } | |
| BIT_addBits(&blockStream, sequences[nbSeq-1].offBase >> extraBits, | |
| ofBits - extraBits); | |
| } else { | |
| BIT_addBits(&blockStream, sequences[nbSeq-1].offBase, ofCodeTable[nbSeq-1]); | |
| } | |
| BIT_flushBits(&blockStream); | |
| { size_t n; | |
| for (n=nbSeq-2 ; n<nbSeq ; n--) { /* intentional underflow */ | |
| BYTE const llCode = llCodeTable[n]; | |
| BYTE const ofCode = ofCodeTable[n]; | |
| BYTE const mlCode = mlCodeTable[n]; | |
| U32 const llBits = LL_bits[llCode]; | |
| U32 const ofBits = ofCode; | |
| U32 const mlBits = ML_bits[mlCode]; | |
| DEBUGLOG(6, "encoding: litlen:%2u - matchlen:%2u - offCode:%7u", | |
| (unsigned)sequences[n].litLength, | |
| (unsigned)sequences[n].mlBase + MINMATCH, | |
| (unsigned)sequences[n].offBase); | |
| /* 32b*/ /* 64b*/ | |
| /* (7)*/ /* (7)*/ | |
| FSE_encodeSymbol(&blockStream, &stateOffsetBits, ofCode); /* 15 */ /* 15 */ | |
| FSE_encodeSymbol(&blockStream, &stateMatchLength, mlCode); /* 24 */ /* 24 */ | |
| if (MEM_32bits()) BIT_flushBits(&blockStream); /* (7)*/ | |
| FSE_encodeSymbol(&blockStream, &stateLitLength, llCode); /* 16 */ /* 33 */ | |
| if (MEM_32bits() || (ofBits+mlBits+llBits >= 64-7-(LLFSELog+MLFSELog+OffFSELog))) | |
| BIT_flushBits(&blockStream); /* (7)*/ | |
| BIT_addBits(&blockStream, sequences[n].litLength, llBits); | |
| if (MEM_32bits() && ((llBits+mlBits)>24)) BIT_flushBits(&blockStream); | |
| BIT_addBits(&blockStream, sequences[n].mlBase, mlBits); | |
| if (MEM_32bits() || (ofBits+mlBits+llBits > 56)) BIT_flushBits(&blockStream); | |
| if (longOffsets) { | |
| unsigned const extraBits = ofBits - MIN(ofBits, STREAM_ACCUMULATOR_MIN-1); | |
| if (extraBits) { | |
| BIT_addBits(&blockStream, sequences[n].offBase, extraBits); | |
| BIT_flushBits(&blockStream); /* (7)*/ | |
| } | |
| BIT_addBits(&blockStream, sequences[n].offBase >> extraBits, | |
| ofBits - extraBits); /* 31 */ | |
| } else { | |
| BIT_addBits(&blockStream, sequences[n].offBase, ofBits); /* 31 */ | |
| } | |
| BIT_flushBits(&blockStream); /* (7)*/ | |
| DEBUGLOG(7, "remaining space : %i", (int)(blockStream.endPtr - blockStream.ptr)); | |
| } } | |
| DEBUGLOG(6, "ZSTD_encodeSequences: flushing ML state with %u bits", stateMatchLength.stateLog); | |
| FSE_flushCState(&blockStream, &stateMatchLength); | |
| DEBUGLOG(6, "ZSTD_encodeSequences: flushing Off state with %u bits", stateOffsetBits.stateLog); | |
| FSE_flushCState(&blockStream, &stateOffsetBits); | |
| DEBUGLOG(6, "ZSTD_encodeSequences: flushing LL state with %u bits", stateLitLength.stateLog); | |
| FSE_flushCState(&blockStream, &stateLitLength); | |
| { size_t const streamSize = BIT_closeCStream(&blockStream); | |
| RETURN_ERROR_IF(streamSize==0, dstSize_tooSmall, "not enough space"); | |
| return streamSize; | |
| } | |
| } | |
| static size_t | |
| ZSTD_encodeSequences_default( | |
| void* dst, size_t dstCapacity, | |
| FSE_CTable const* CTable_MatchLength, BYTE const* mlCodeTable, | |
| FSE_CTable const* CTable_OffsetBits, BYTE const* ofCodeTable, | |
| FSE_CTable const* CTable_LitLength, BYTE const* llCodeTable, | |
| SeqDef const* sequences, size_t nbSeq, int longOffsets) | |
| { | |
| return ZSTD_encodeSequences_body(dst, dstCapacity, | |
| CTable_MatchLength, mlCodeTable, | |
| CTable_OffsetBits, ofCodeTable, | |
| CTable_LitLength, llCodeTable, | |
| sequences, nbSeq, longOffsets); | |
| } | |
| #if DYNAMIC_BMI2 | |
| static BMI2_TARGET_ATTRIBUTE size_t | |
| ZSTD_encodeSequences_bmi2( | |
| void* dst, size_t dstCapacity, | |
| FSE_CTable const* CTable_MatchLength, BYTE const* mlCodeTable, | |
| FSE_CTable const* CTable_OffsetBits, BYTE const* ofCodeTable, | |
| FSE_CTable const* CTable_LitLength, BYTE const* llCodeTable, | |
| SeqDef const* sequences, size_t nbSeq, int longOffsets) | |
| { | |
| return ZSTD_encodeSequences_body(dst, dstCapacity, | |
| CTable_MatchLength, mlCodeTable, | |
| CTable_OffsetBits, ofCodeTable, | |
| CTable_LitLength, llCodeTable, | |
| sequences, nbSeq, longOffsets); | |
| } | |
| #endif | |
| size_t ZSTD_encodeSequences( | |
| void* dst, size_t dstCapacity, | |
| FSE_CTable const* CTable_MatchLength, BYTE const* mlCodeTable, | |
| FSE_CTable const* CTable_OffsetBits, BYTE const* ofCodeTable, | |
| FSE_CTable const* CTable_LitLength, BYTE const* llCodeTable, | |
| SeqDef const* sequences, size_t nbSeq, int longOffsets, int bmi2) | |
| { | |
| DEBUGLOG(5, "ZSTD_encodeSequences: dstCapacity = %u", (unsigned)dstCapacity); | |
| #if DYNAMIC_BMI2 | |
| if (bmi2) { | |
| return ZSTD_encodeSequences_bmi2(dst, dstCapacity, | |
| CTable_MatchLength, mlCodeTable, | |
| CTable_OffsetBits, ofCodeTable, | |
| CTable_LitLength, llCodeTable, | |
| sequences, nbSeq, longOffsets); | |
| } | |
| #endif | |
| (void)bmi2; | |
| return ZSTD_encodeSequences_default(dst, dstCapacity, | |
| CTable_MatchLength, mlCodeTable, | |
| CTable_OffsetBits, ofCodeTable, | |
| CTable_LitLength, llCodeTable, | |
| sequences, nbSeq, longOffsets); | |
| } |