--- /dev/null
+/*
+ * Copyright (c) 2016-2020, 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 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), "");
+ 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;
+}
+
+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:
+ 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: {
+ S16 norm[MaxSeq + 1];
+ 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);
+ FORWARD_IF_ERROR(FSE_normalizeCount(norm, tableLog, count, nbSeq_1, max), "");
+ { size_t const NCountSize = FSE_writeNCount(op, oend - op, norm, max, tableLog); /* overflow protected */
+ FORWARD_IF_ERROR(NCountSize, "FSE_writeNCount failed");
+ FORWARD_IF_ERROR(FSE_buildCTable_wksp(nextCTable, norm, max, tableLog, entropyWorkspace, entropyWorkspaceSize), "");
+ 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);
+}
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