| /* |
| * Copyright (c) Yann Collet, Facebook, Inc. |
| * 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 |
| * comprssibility. |
| */ |
| 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; |
| 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 less 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)), ""); |
| { size_t const NCountSize = FSE_writeNCount(op, 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)), ""); |
| 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].matchLength, 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].offset, extraBits); |
| BIT_flushBits(&blockStream); |
| } |
| BIT_addBits(&blockStream, sequences[nbSeq-1].offset >> extraBits, |
| ofBits - extraBits); |
| } else { |
| BIT_addBits(&blockStream, sequences[nbSeq-1].offset, 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].matchLength + MINMATCH, |
| (unsigned)sequences[n].offset); |
| /* 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].matchLength, 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].offset, extraBits); |
| BIT_flushBits(&blockStream); /* (7)*/ |
| } |
| BIT_addBits(&blockStream, sequences[n].offset >> extraBits, |
| ofBits - extraBits); /* 31 */ |
| } else { |
| BIT_addBits(&blockStream, sequences[n].offset, 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 TARGET_ATTRIBUTE("bmi2") 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); |
| } |
