diff options
Diffstat (limited to 'lib/zstd/compress/zstd_compress_sequences.c')
| -rw-r--r-- | lib/zstd/compress/zstd_compress_sequences.c | 442 |
1 files changed, 442 insertions, 0 deletions
diff --git a/lib/zstd/compress/zstd_compress_sequences.c b/lib/zstd/compress/zstd_compress_sequences.c new file mode 100644 index 000000000000..21ddc1b37acf --- /dev/null +++ b/lib/zstd/compress/zstd_compress_sequences.c @@ -0,0 +1,442 @@ +/* + * 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; + + 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 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)), "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); +} |