// 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_eZSTD_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_tZSTD_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_tZSTD_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_tZSTD_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_tZSTD_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);}
// 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);
}