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1/* ******************************************************************2 * Huffman encoder, part of New Generation Entropy library3 * Copyright (c) Yann Collet, Facebook, Inc.4 *5 * You can contact the author at :6 * - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy7 * - Public forum : https://groups.google.com/forum/#!forum/lz4c8 *9 * This source code is licensed under both the BSD-style license (found in the10 * LICENSE file in the root directory of this source tree) and the GPLv2 (found11 * in the COPYING file in the root directory of this source tree).12 * You may select, at your option, one of the above-listed licenses.13****************************************************************** */14 15/* **************************************************************16* Compiler specifics17****************************************************************/18 19 20/* **************************************************************21* Includes22****************************************************************/23#include "../common/zstd_deps.h" /* ZSTD_memcpy, ZSTD_memset */24#include "../common/compiler.h"25#include "../common/bitstream.h"26#include "hist.h"27#define FSE_STATIC_LINKING_ONLY /* FSE_optimalTableLog_internal */28#include "../common/fse.h" /* header compression */29#define HUF_STATIC_LINKING_ONLY30#include "../common/huf.h"31#include "../common/error_private.h"32 33 34/* **************************************************************35* Error Management36****************************************************************/37#define HUF_isError ERR_isError38#define HUF_STATIC_ASSERT(c) DEBUG_STATIC_ASSERT(c) /* use only *after* variable declarations */39 40 41/* **************************************************************42* Utils43****************************************************************/44unsigned HUF_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue)45{46 return FSE_optimalTableLog_internal(maxTableLog, srcSize, maxSymbolValue, 1);47}48 49 50/* *******************************************************51* HUF : Huffman block compression52*********************************************************/53#define HUF_WORKSPACE_MAX_ALIGNMENT 854 55static void* HUF_alignUpWorkspace(void* workspace, size_t* workspaceSizePtr, size_t align)56{57 size_t const mask = align - 1;58 size_t const rem = (size_t)workspace & mask;59 size_t const add = (align - rem) & mask;60 BYTE* const aligned = (BYTE*)workspace + add;61 assert((align & (align - 1)) == 0); /* pow 2 */62 assert(align <= HUF_WORKSPACE_MAX_ALIGNMENT);63 if (*workspaceSizePtr >= add) {64 assert(add < align);65 assert(((size_t)aligned & mask) == 0);66 *workspaceSizePtr -= add;67 return aligned;68 } else {69 *workspaceSizePtr = 0;70 return NULL;71 }72}73 74 75/* HUF_compressWeights() :76 * Same as FSE_compress(), but dedicated to huff0's weights compression.77 * The use case needs much less stack memory.78 * Note : all elements within weightTable are supposed to be <= HUF_TABLELOG_MAX.79 */80#define MAX_FSE_TABLELOG_FOR_HUFF_HEADER 681 82typedef struct {83 FSE_CTable CTable[FSE_CTABLE_SIZE_U32(MAX_FSE_TABLELOG_FOR_HUFF_HEADER, HUF_TABLELOG_MAX)];84 U32 scratchBuffer[FSE_BUILD_CTABLE_WORKSPACE_SIZE_U32(HUF_TABLELOG_MAX, MAX_FSE_TABLELOG_FOR_HUFF_HEADER)];85 unsigned count[HUF_TABLELOG_MAX+1];86 S16 norm[HUF_TABLELOG_MAX+1];87} HUF_CompressWeightsWksp;88 89static size_t HUF_compressWeights(void* dst, size_t dstSize, const void* weightTable, size_t wtSize, void* workspace, size_t workspaceSize)90{91 BYTE* const ostart = (BYTE*) dst;92 BYTE* op = ostart;93 BYTE* const oend = ostart + dstSize;94 95 unsigned maxSymbolValue = HUF_TABLELOG_MAX;96 U32 tableLog = MAX_FSE_TABLELOG_FOR_HUFF_HEADER;97 HUF_CompressWeightsWksp* wksp = (HUF_CompressWeightsWksp*)HUF_alignUpWorkspace(workspace, &workspaceSize, ZSTD_ALIGNOF(U32));98 99 if (workspaceSize < sizeof(HUF_CompressWeightsWksp)) return ERROR(GENERIC);100 101 /* init conditions */102 if (wtSize <= 1) return 0; /* Not compressible */103 104 /* Scan input and build symbol stats */105 { unsigned const maxCount = HIST_count_simple(wksp->count, &maxSymbolValue, weightTable, wtSize); /* never fails */106 if (maxCount == wtSize) return 1; /* only a single symbol in src : rle */107 if (maxCount == 1) return 0; /* each symbol present maximum once => not compressible */108 }109 110 tableLog = FSE_optimalTableLog(tableLog, wtSize, maxSymbolValue);111 CHECK_F( FSE_normalizeCount(wksp->norm, tableLog, wksp->count, wtSize, maxSymbolValue, /* useLowProbCount */ 0) );112 113 /* Write table description header */114 { CHECK_V_F(hSize, FSE_writeNCount(op, (size_t)(oend-op), wksp->norm, maxSymbolValue, tableLog) );115 op += hSize;116 }117 118 /* Compress */119 CHECK_F( FSE_buildCTable_wksp(wksp->CTable, wksp->norm, maxSymbolValue, tableLog, wksp->scratchBuffer, sizeof(wksp->scratchBuffer)) );120 { CHECK_V_F(cSize, FSE_compress_usingCTable(op, (size_t)(oend - op), weightTable, wtSize, wksp->CTable) );121 if (cSize == 0) return 0; /* not enough space for compressed data */122 op += cSize;123 }124 125 return (size_t)(op-ostart);126}127 128static size_t HUF_getNbBits(HUF_CElt elt)129{130 return elt & 0xFF;131}132 133static size_t HUF_getNbBitsFast(HUF_CElt elt)134{135 return elt;136}137 138static size_t HUF_getValue(HUF_CElt elt)139{140 return elt & ~0xFF;141}142 143static size_t HUF_getValueFast(HUF_CElt elt)144{145 return elt;146}147 148static void HUF_setNbBits(HUF_CElt* elt, size_t nbBits)149{150 assert(nbBits <= HUF_TABLELOG_ABSOLUTEMAX);151 *elt = nbBits;152}153 154static void HUF_setValue(HUF_CElt* elt, size_t value)155{156 size_t const nbBits = HUF_getNbBits(*elt);157 if (nbBits > 0) {158 assert((value >> nbBits) == 0);159 *elt |= value << (sizeof(HUF_CElt) * 8 - nbBits);160 }161}162 163typedef struct {164 HUF_CompressWeightsWksp wksp;165 BYTE bitsToWeight[HUF_TABLELOG_MAX + 1]; /* precomputed conversion table */166 BYTE huffWeight[HUF_SYMBOLVALUE_MAX];167} HUF_WriteCTableWksp;168 169size_t HUF_writeCTable_wksp(void* dst, size_t maxDstSize,170 const HUF_CElt* CTable, unsigned maxSymbolValue, unsigned huffLog,171 void* workspace, size_t workspaceSize)172{173 HUF_CElt const* const ct = CTable + 1;174 BYTE* op = (BYTE*)dst;175 U32 n;176 HUF_WriteCTableWksp* wksp = (HUF_WriteCTableWksp*)HUF_alignUpWorkspace(workspace, &workspaceSize, ZSTD_ALIGNOF(U32));177 178 /* check conditions */179 if (workspaceSize < sizeof(HUF_WriteCTableWksp)) return ERROR(GENERIC);180 if (maxSymbolValue > HUF_SYMBOLVALUE_MAX) return ERROR(maxSymbolValue_tooLarge);181 182 /* convert to weight */183 wksp->bitsToWeight[0] = 0;184 for (n=1; n<huffLog+1; n++)185 wksp->bitsToWeight[n] = (BYTE)(huffLog + 1 - n);186 for (n=0; n<maxSymbolValue; n++)187 wksp->huffWeight[n] = wksp->bitsToWeight[HUF_getNbBits(ct[n])];188 189 /* attempt weights compression by FSE */190 if (maxDstSize < 1) return ERROR(dstSize_tooSmall);191 { CHECK_V_F(hSize, HUF_compressWeights(op+1, maxDstSize-1, wksp->huffWeight, maxSymbolValue, &wksp->wksp, sizeof(wksp->wksp)) );192 if ((hSize>1) & (hSize < maxSymbolValue/2)) { /* FSE compressed */193 op[0] = (BYTE)hSize;194 return hSize+1;195 } }196 197 /* write raw values as 4-bits (max : 15) */198 if (maxSymbolValue > (256-128)) return ERROR(GENERIC); /* should not happen : likely means source cannot be compressed */199 if (((maxSymbolValue+1)/2) + 1 > maxDstSize) return ERROR(dstSize_tooSmall); /* not enough space within dst buffer */200 op[0] = (BYTE)(128 /*special case*/ + (maxSymbolValue-1));201 wksp->huffWeight[maxSymbolValue] = 0; /* to be sure it doesn't cause msan issue in final combination */202 for (n=0; n<maxSymbolValue; n+=2)203 op[(n/2)+1] = (BYTE)((wksp->huffWeight[n] << 4) + wksp->huffWeight[n+1]);204 return ((maxSymbolValue+1)/2) + 1;205}206 207/*! HUF_writeCTable() :208 `CTable` : Huffman tree to save, using huf representation.209 @return : size of saved CTable */210size_t HUF_writeCTable (void* dst, size_t maxDstSize,211 const HUF_CElt* CTable, unsigned maxSymbolValue, unsigned huffLog)212{213 HUF_WriteCTableWksp wksp;214 return HUF_writeCTable_wksp(dst, maxDstSize, CTable, maxSymbolValue, huffLog, &wksp, sizeof(wksp));215}216 217 218size_t HUF_readCTable (HUF_CElt* CTable, unsigned* maxSymbolValuePtr, const void* src, size_t srcSize, unsigned* hasZeroWeights)219{220 BYTE huffWeight[HUF_SYMBOLVALUE_MAX + 1]; /* init not required, even though some static analyzer may complain */221 U32 rankVal[HUF_TABLELOG_ABSOLUTEMAX + 1]; /* large enough for values from 0 to 16 */222 U32 tableLog = 0;223 U32 nbSymbols = 0;224 HUF_CElt* const ct = CTable + 1;225 226 /* get symbol weights */227 CHECK_V_F(readSize, HUF_readStats(huffWeight, HUF_SYMBOLVALUE_MAX+1, rankVal, &nbSymbols, &tableLog, src, srcSize));228 *hasZeroWeights = (rankVal[0] > 0);229 230 /* check result */231 if (tableLog > HUF_TABLELOG_MAX) return ERROR(tableLog_tooLarge);232 if (nbSymbols > *maxSymbolValuePtr+1) return ERROR(maxSymbolValue_tooSmall);233 234 CTable[0] = tableLog;235 236 /* Prepare base value per rank */237 { U32 n, nextRankStart = 0;238 for (n=1; n<=tableLog; n++) {239 U32 curr = nextRankStart;240 nextRankStart += (rankVal[n] << (n-1));241 rankVal[n] = curr;242 } }243 244 /* fill nbBits */245 { U32 n; for (n=0; n<nbSymbols; n++) {246 const U32 w = huffWeight[n];247 HUF_setNbBits(ct + n, (BYTE)(tableLog + 1 - w) & -(w != 0));248 } }249 250 /* fill val */251 { U16 nbPerRank[HUF_TABLELOG_MAX+2] = {0}; /* support w=0=>n=tableLog+1 */252 U16 valPerRank[HUF_TABLELOG_MAX+2] = {0};253 { U32 n; for (n=0; n<nbSymbols; n++) nbPerRank[HUF_getNbBits(ct[n])]++; }254 /* determine stating value per rank */255 valPerRank[tableLog+1] = 0; /* for w==0 */256 { U16 min = 0;257 U32 n; for (n=tableLog; n>0; n--) { /* start at n=tablelog <-> w=1 */258 valPerRank[n] = min; /* get starting value within each rank */259 min += nbPerRank[n];260 min >>= 1;261 } }262 /* assign value within rank, symbol order */263 { U32 n; for (n=0; n<nbSymbols; n++) HUF_setValue(ct + n, valPerRank[HUF_getNbBits(ct[n])]++); }264 }265 266 *maxSymbolValuePtr = nbSymbols - 1;267 return readSize;268}269 270U32 HUF_getNbBitsFromCTable(HUF_CElt const* CTable, U32 symbolValue)271{272 const HUF_CElt* ct = CTable + 1;273 assert(symbolValue <= HUF_SYMBOLVALUE_MAX);274 return (U32)HUF_getNbBits(ct[symbolValue]);275}276 277 278typedef struct nodeElt_s {279 U32 count;280 U16 parent;281 BYTE byte;282 BYTE nbBits;283} nodeElt;284 285/*286 * HUF_setMaxHeight():287 * Enforces maxNbBits on the Huffman tree described in huffNode.288 *289 * It sets all nodes with nbBits > maxNbBits to be maxNbBits. Then it adjusts290 * the tree to so that it is a valid canonical Huffman tree.291 *292 * @pre The sum of the ranks of each symbol == 2^largestBits,293 * where largestBits == huffNode[lastNonNull].nbBits.294 * @post The sum of the ranks of each symbol == 2^largestBits,295 * where largestBits is the return value <= maxNbBits.296 *297 * @param huffNode The Huffman tree modified in place to enforce maxNbBits.298 * @param lastNonNull The symbol with the lowest count in the Huffman tree.299 * @param maxNbBits The maximum allowed number of bits, which the Huffman tree300 * may not respect. After this function the Huffman tree will301 * respect maxNbBits.302 * @return The maximum number of bits of the Huffman tree after adjustment,303 * necessarily no more than maxNbBits.304 */305static U32 HUF_setMaxHeight(nodeElt* huffNode, U32 lastNonNull, U32 maxNbBits)306{307 const U32 largestBits = huffNode[lastNonNull].nbBits;308 /* early exit : no elt > maxNbBits, so the tree is already valid. */309 if (largestBits <= maxNbBits) return largestBits;310 311 /* there are several too large elements (at least >= 2) */312 { int totalCost = 0;313 const U32 baseCost = 1 << (largestBits - maxNbBits);314 int n = (int)lastNonNull;315 316 /* Adjust any ranks > maxNbBits to maxNbBits.317 * Compute totalCost, which is how far the sum of the ranks is318 * we are over 2^largestBits after adjust the offending ranks.319 */320 while (huffNode[n].nbBits > maxNbBits) {321 totalCost += baseCost - (1 << (largestBits - huffNode[n].nbBits));322 huffNode[n].nbBits = (BYTE)maxNbBits;323 n--;324 }325 /* n stops at huffNode[n].nbBits <= maxNbBits */326 assert(huffNode[n].nbBits <= maxNbBits);327 /* n end at index of smallest symbol using < maxNbBits */328 while (huffNode[n].nbBits == maxNbBits) --n;329 330 /* renorm totalCost from 2^largestBits to 2^maxNbBits331 * note : totalCost is necessarily a multiple of baseCost */332 assert((totalCost & (baseCost - 1)) == 0);333 totalCost >>= (largestBits - maxNbBits);334 assert(totalCost > 0);335 336 /* repay normalized cost */337 { U32 const noSymbol = 0xF0F0F0F0;338 U32 rankLast[HUF_TABLELOG_MAX+2];339 340 /* Get pos of last (smallest = lowest cum. count) symbol per rank */341 ZSTD_memset(rankLast, 0xF0, sizeof(rankLast));342 { U32 currentNbBits = maxNbBits;343 int pos;344 for (pos=n ; pos >= 0; pos--) {345 if (huffNode[pos].nbBits >= currentNbBits) continue;346 currentNbBits = huffNode[pos].nbBits; /* < maxNbBits */347 rankLast[maxNbBits-currentNbBits] = (U32)pos;348 } }349 350 while (totalCost > 0) {351 /* Try to reduce the next power of 2 above totalCost because we352 * gain back half the rank.353 */354 U32 nBitsToDecrease = BIT_highbit32((U32)totalCost) + 1;355 for ( ; nBitsToDecrease > 1; nBitsToDecrease--) {356 U32 const highPos = rankLast[nBitsToDecrease];357 U32 const lowPos = rankLast[nBitsToDecrease-1];358 if (highPos == noSymbol) continue;359 /* Decrease highPos if no symbols of lowPos or if it is360 * not cheaper to remove 2 lowPos than highPos.361 */362 if (lowPos == noSymbol) break;363 { U32 const highTotal = huffNode[highPos].count;364 U32 const lowTotal = 2 * huffNode[lowPos].count;365 if (highTotal <= lowTotal) break;366 } }367 /* only triggered when no more rank 1 symbol left => find closest one (note : there is necessarily at least one !) */368 assert(rankLast[nBitsToDecrease] != noSymbol || nBitsToDecrease == 1);369 /* HUF_MAX_TABLELOG test just to please gcc 5+; but it should not be necessary */370 while ((nBitsToDecrease<=HUF_TABLELOG_MAX) && (rankLast[nBitsToDecrease] == noSymbol))371 nBitsToDecrease++;372 assert(rankLast[nBitsToDecrease] != noSymbol);373 /* Increase the number of bits to gain back half the rank cost. */374 totalCost -= 1 << (nBitsToDecrease-1);375 huffNode[rankLast[nBitsToDecrease]].nbBits++;376 377 /* Fix up the new rank.378 * If the new rank was empty, this symbol is now its smallest.379 * Otherwise, this symbol will be the largest in the new rank so no adjustment.380 */381 if (rankLast[nBitsToDecrease-1] == noSymbol)382 rankLast[nBitsToDecrease-1] = rankLast[nBitsToDecrease];383 /* Fix up the old rank.384 * If the symbol was at position 0, meaning it was the highest weight symbol in the tree,385 * it must be the only symbol in its rank, so the old rank now has no symbols.386 * Otherwise, since the Huffman nodes are sorted by count, the previous position is now387 * the smallest node in the rank. If the previous position belongs to a different rank,388 * then the rank is now empty.389 */390 if (rankLast[nBitsToDecrease] == 0) /* special case, reached largest symbol */391 rankLast[nBitsToDecrease] = noSymbol;392 else {393 rankLast[nBitsToDecrease]--;394 if (huffNode[rankLast[nBitsToDecrease]].nbBits != maxNbBits-nBitsToDecrease)395 rankLast[nBitsToDecrease] = noSymbol; /* this rank is now empty */396 }397 } /* while (totalCost > 0) */398 399 /* If we've removed too much weight, then we have to add it back.400 * To avoid overshooting again, we only adjust the smallest rank.401 * We take the largest nodes from the lowest rank 0 and move them402 * to rank 1. There's guaranteed to be enough rank 0 symbols because403 * TODO.404 */405 while (totalCost < 0) { /* Sometimes, cost correction overshoot */406 /* special case : no rank 1 symbol (using maxNbBits-1);407 * let's create one from largest rank 0 (using maxNbBits).408 */409 if (rankLast[1] == noSymbol) {410 while (huffNode[n].nbBits == maxNbBits) n--;411 huffNode[n+1].nbBits--;412 assert(n >= 0);413 rankLast[1] = (U32)(n+1);414 totalCost++;415 continue;416 }417 huffNode[ rankLast[1] + 1 ].nbBits--;418 rankLast[1]++;419 totalCost ++;420 }421 } /* repay normalized cost */422 } /* there are several too large elements (at least >= 2) */423 424 return maxNbBits;425}426 427typedef struct {428 U16 base;429 U16 curr;430} rankPos;431 432typedef nodeElt huffNodeTable[HUF_CTABLE_WORKSPACE_SIZE_U32];433 434/* Number of buckets available for HUF_sort() */435#define RANK_POSITION_TABLE_SIZE 192436 437typedef struct {438 huffNodeTable huffNodeTbl;439 rankPos rankPosition[RANK_POSITION_TABLE_SIZE];440} HUF_buildCTable_wksp_tables;441 442/* RANK_POSITION_DISTINCT_COUNT_CUTOFF == Cutoff point in HUF_sort() buckets for which we use log2 bucketing.443 * Strategy is to use as many buckets as possible for representing distinct444 * counts while using the remainder to represent all "large" counts.445 *446 * To satisfy this requirement for 192 buckets, we can do the following:447 * Let buckets 0-166 represent distinct counts of [0, 166]448 * Let buckets 166 to 192 represent all remaining counts up to RANK_POSITION_MAX_COUNT_LOG using log2 bucketing.449 */450#define RANK_POSITION_MAX_COUNT_LOG 32451#define RANK_POSITION_LOG_BUCKETS_BEGIN (RANK_POSITION_TABLE_SIZE - 1) - RANK_POSITION_MAX_COUNT_LOG - 1 /* == 158 */452#define RANK_POSITION_DISTINCT_COUNT_CUTOFF RANK_POSITION_LOG_BUCKETS_BEGIN + BIT_highbit32(RANK_POSITION_LOG_BUCKETS_BEGIN) /* == 166 */453 454/* Return the appropriate bucket index for a given count. See definition of455 * RANK_POSITION_DISTINCT_COUNT_CUTOFF for explanation of bucketing strategy.456 */457static U32 HUF_getIndex(U32 const count) {458 return (count < RANK_POSITION_DISTINCT_COUNT_CUTOFF)459 ? count460 : BIT_highbit32(count) + RANK_POSITION_LOG_BUCKETS_BEGIN;461}462 463/* Helper swap function for HUF_quickSortPartition() */464static void HUF_swapNodes(nodeElt* a, nodeElt* b) {465 nodeElt tmp = *a;466 *a = *b;467 *b = tmp;468}469 470/* Returns 0 if the huffNode array is not sorted by descending count */471MEM_STATIC int HUF_isSorted(nodeElt huffNode[], U32 const maxSymbolValue1) {472 U32 i;473 for (i = 1; i < maxSymbolValue1; ++i) {474 if (huffNode[i].count > huffNode[i-1].count) {475 return 0;476 }477 }478 return 1;479}480 481/* Insertion sort by descending order */482HINT_INLINE void HUF_insertionSort(nodeElt huffNode[], int const low, int const high) {483 int i;484 int const size = high-low+1;485 huffNode += low;486 for (i = 1; i < size; ++i) {487 nodeElt const key = huffNode[i];488 int j = i - 1;489 while (j >= 0 && huffNode[j].count < key.count) {490 huffNode[j + 1] = huffNode[j];491 j--;492 }493 huffNode[j + 1] = key;494 }495}496 497/* Pivot helper function for quicksort. */498static int HUF_quickSortPartition(nodeElt arr[], int const low, int const high) {499 /* Simply select rightmost element as pivot. "Better" selectors like500 * median-of-three don't experimentally appear to have any benefit.501 */502 U32 const pivot = arr[high].count;503 int i = low - 1;504 int j = low;505 for ( ; j < high; j++) {506 if (arr[j].count > pivot) {507 i++;508 HUF_swapNodes(&arr[i], &arr[j]);509 }510 }511 HUF_swapNodes(&arr[i + 1], &arr[high]);512 return i + 1;513}514 515/* Classic quicksort by descending with partially iterative calls516 * to reduce worst case callstack size.517 */518static void HUF_simpleQuickSort(nodeElt arr[], int low, int high) {519 int const kInsertionSortThreshold = 8;520 if (high - low < kInsertionSortThreshold) {521 HUF_insertionSort(arr, low, high);522 return;523 }524 while (low < high) {525 int const idx = HUF_quickSortPartition(arr, low, high);526 if (idx - low < high - idx) {527 HUF_simpleQuickSort(arr, low, idx - 1);528 low = idx + 1;529 } else {530 HUF_simpleQuickSort(arr, idx + 1, high);531 high = idx - 1;532 }533 }534}535 536/*537 * HUF_sort():538 * Sorts the symbols [0, maxSymbolValue] by count[symbol] in decreasing order.539 * This is a typical bucket sorting strategy that uses either quicksort or insertion sort to sort each bucket.540 *541 * @param[out] huffNode Sorted symbols by decreasing count. Only members `.count` and `.byte` are filled.542 * Must have (maxSymbolValue + 1) entries.543 * @param[in] count Histogram of the symbols.544 * @param[in] maxSymbolValue Maximum symbol value.545 * @param rankPosition This is a scratch workspace. Must have RANK_POSITION_TABLE_SIZE entries.546 */547static void HUF_sort(nodeElt huffNode[], const unsigned count[], U32 const maxSymbolValue, rankPos rankPosition[]) {548 U32 n;549 U32 const maxSymbolValue1 = maxSymbolValue+1;550 551 /* Compute base and set curr to base.552 * For symbol s let lowerRank = HUF_getIndex(count[n]) and rank = lowerRank + 1.553 * See HUF_getIndex to see bucketing strategy.554 * We attribute each symbol to lowerRank's base value, because we want to know where555 * each rank begins in the output, so for rank R we want to count ranks R+1 and above.556 */557 ZSTD_memset(rankPosition, 0, sizeof(*rankPosition) * RANK_POSITION_TABLE_SIZE);558 for (n = 0; n < maxSymbolValue1; ++n) {559 U32 lowerRank = HUF_getIndex(count[n]);560 assert(lowerRank < RANK_POSITION_TABLE_SIZE - 1);561 rankPosition[lowerRank].base++;562 }563 564 assert(rankPosition[RANK_POSITION_TABLE_SIZE - 1].base == 0);565 /* Set up the rankPosition table */566 for (n = RANK_POSITION_TABLE_SIZE - 1; n > 0; --n) {567 rankPosition[n-1].base += rankPosition[n].base;568 rankPosition[n-1].curr = rankPosition[n-1].base;569 }570 571 /* Insert each symbol into their appropriate bucket, setting up rankPosition table. */572 for (n = 0; n < maxSymbolValue1; ++n) {573 U32 const c = count[n];574 U32 const r = HUF_getIndex(c) + 1;575 U32 const pos = rankPosition[r].curr++;576 assert(pos < maxSymbolValue1);577 huffNode[pos].count = c;578 huffNode[pos].byte = (BYTE)n;579 }580 581 /* Sort each bucket. */582 for (n = RANK_POSITION_DISTINCT_COUNT_CUTOFF; n < RANK_POSITION_TABLE_SIZE - 1; ++n) {583 U32 const bucketSize = rankPosition[n].curr-rankPosition[n].base;584 U32 const bucketStartIdx = rankPosition[n].base;585 if (bucketSize > 1) {586 assert(bucketStartIdx < maxSymbolValue1);587 HUF_simpleQuickSort(huffNode + bucketStartIdx, 0, bucketSize-1);588 }589 }590 591 assert(HUF_isSorted(huffNode, maxSymbolValue1));592}593 594/* HUF_buildCTable_wksp() :595 * Same as HUF_buildCTable(), but using externally allocated scratch buffer.596 * `workSpace` must be aligned on 4-bytes boundaries, and be at least as large as sizeof(HUF_buildCTable_wksp_tables).597 */598#define STARTNODE (HUF_SYMBOLVALUE_MAX+1)599 600/* HUF_buildTree():601 * Takes the huffNode array sorted by HUF_sort() and builds an unlimited-depth Huffman tree.602 *603 * @param huffNode The array sorted by HUF_sort(). Builds the Huffman tree in this array.604 * @param maxSymbolValue The maximum symbol value.605 * @return The smallest node in the Huffman tree (by count).606 */607static int HUF_buildTree(nodeElt* huffNode, U32 maxSymbolValue)608{609 nodeElt* const huffNode0 = huffNode - 1;610 int nonNullRank;611 int lowS, lowN;612 int nodeNb = STARTNODE;613 int n, nodeRoot;614 /* init for parents */615 nonNullRank = (int)maxSymbolValue;616 while(huffNode[nonNullRank].count == 0) nonNullRank--;617 lowS = nonNullRank; nodeRoot = nodeNb + lowS - 1; lowN = nodeNb;618 huffNode[nodeNb].count = huffNode[lowS].count + huffNode[lowS-1].count;619 huffNode[lowS].parent = huffNode[lowS-1].parent = (U16)nodeNb;620 nodeNb++; lowS-=2;621 for (n=nodeNb; n<=nodeRoot; n++) huffNode[n].count = (U32)(1U<<30);622 huffNode0[0].count = (U32)(1U<<31); /* fake entry, strong barrier */623 624 /* create parents */625 while (nodeNb <= nodeRoot) {626 int const n1 = (huffNode[lowS].count < huffNode[lowN].count) ? lowS-- : lowN++;627 int const n2 = (huffNode[lowS].count < huffNode[lowN].count) ? lowS-- : lowN++;628 huffNode[nodeNb].count = huffNode[n1].count + huffNode[n2].count;629 huffNode[n1].parent = huffNode[n2].parent = (U16)nodeNb;630 nodeNb++;631 }632 633 /* distribute weights (unlimited tree height) */634 huffNode[nodeRoot].nbBits = 0;635 for (n=nodeRoot-1; n>=STARTNODE; n--)636 huffNode[n].nbBits = huffNode[ huffNode[n].parent ].nbBits + 1;637 for (n=0; n<=nonNullRank; n++)638 huffNode[n].nbBits = huffNode[ huffNode[n].parent ].nbBits + 1;639 640 return nonNullRank;641}642 643/*644 * HUF_buildCTableFromTree():645 * Build the CTable given the Huffman tree in huffNode.646 *647 * @param[out] CTable The output Huffman CTable.648 * @param huffNode The Huffman tree.649 * @param nonNullRank The last and smallest node in the Huffman tree.650 * @param maxSymbolValue The maximum symbol value.651 * @param maxNbBits The exact maximum number of bits used in the Huffman tree.652 */653static void HUF_buildCTableFromTree(HUF_CElt* CTable, nodeElt const* huffNode, int nonNullRank, U32 maxSymbolValue, U32 maxNbBits)654{655 HUF_CElt* const ct = CTable + 1;656 /* fill result into ctable (val, nbBits) */657 int n;658 U16 nbPerRank[HUF_TABLELOG_MAX+1] = {0};659 U16 valPerRank[HUF_TABLELOG_MAX+1] = {0};660 int const alphabetSize = (int)(maxSymbolValue + 1);661 for (n=0; n<=nonNullRank; n++)662 nbPerRank[huffNode[n].nbBits]++;663 /* determine starting value per rank */664 { U16 min = 0;665 for (n=(int)maxNbBits; n>0; n--) {666 valPerRank[n] = min; /* get starting value within each rank */667 min += nbPerRank[n];668 min >>= 1;669 } }670 for (n=0; n<alphabetSize; n++)671 HUF_setNbBits(ct + huffNode[n].byte, huffNode[n].nbBits); /* push nbBits per symbol, symbol order */672 for (n=0; n<alphabetSize; n++)673 HUF_setValue(ct + n, valPerRank[HUF_getNbBits(ct[n])]++); /* assign value within rank, symbol order */674 CTable[0] = maxNbBits;675}676 677size_t HUF_buildCTable_wksp (HUF_CElt* CTable, const unsigned* count, U32 maxSymbolValue, U32 maxNbBits, void* workSpace, size_t wkspSize)678{679 HUF_buildCTable_wksp_tables* const wksp_tables = (HUF_buildCTable_wksp_tables*)HUF_alignUpWorkspace(workSpace, &wkspSize, ZSTD_ALIGNOF(U32));680 nodeElt* const huffNode0 = wksp_tables->huffNodeTbl;681 nodeElt* const huffNode = huffNode0+1;682 int nonNullRank;683 684 /* safety checks */685 if (wkspSize < sizeof(HUF_buildCTable_wksp_tables))686 return ERROR(workSpace_tooSmall);687 if (maxNbBits == 0) maxNbBits = HUF_TABLELOG_DEFAULT;688 if (maxSymbolValue > HUF_SYMBOLVALUE_MAX)689 return ERROR(maxSymbolValue_tooLarge);690 ZSTD_memset(huffNode0, 0, sizeof(huffNodeTable));691 692 /* sort, decreasing order */693 HUF_sort(huffNode, count, maxSymbolValue, wksp_tables->rankPosition);694 695 /* build tree */696 nonNullRank = HUF_buildTree(huffNode, maxSymbolValue);697 698 /* enforce maxTableLog */699 maxNbBits = HUF_setMaxHeight(huffNode, (U32)nonNullRank, maxNbBits);700 if (maxNbBits > HUF_TABLELOG_MAX) return ERROR(GENERIC); /* check fit into table */701 702 HUF_buildCTableFromTree(CTable, huffNode, nonNullRank, maxSymbolValue, maxNbBits);703 704 return maxNbBits;705}706 707size_t HUF_estimateCompressedSize(const HUF_CElt* CTable, const unsigned* count, unsigned maxSymbolValue)708{709 HUF_CElt const* ct = CTable + 1;710 size_t nbBits = 0;711 int s;712 for (s = 0; s <= (int)maxSymbolValue; ++s) {713 nbBits += HUF_getNbBits(ct[s]) * count[s];714 }715 return nbBits >> 3;716}717 718int HUF_validateCTable(const HUF_CElt* CTable, const unsigned* count, unsigned maxSymbolValue) {719 HUF_CElt const* ct = CTable + 1;720 int bad = 0;721 int s;722 for (s = 0; s <= (int)maxSymbolValue; ++s) {723 bad |= (count[s] != 0) & (HUF_getNbBits(ct[s]) == 0);724 }725 return !bad;726}727 728size_t HUF_compressBound(size_t size) { return HUF_COMPRESSBOUND(size); }729 730/* HUF_CStream_t:731 * Huffman uses its own BIT_CStream_t implementation.732 * There are three major differences from BIT_CStream_t:733 * 1. HUF_addBits() takes a HUF_CElt (size_t) which is734 * the pair (nbBits, value) in the format:735 * format:736 * - Bits [0, 4) = nbBits737 * - Bits [4, 64 - nbBits) = 0738 * - Bits [64 - nbBits, 64) = value739 * 2. The bitContainer is built from the upper bits and740 * right shifted. E.g. to add a new value of N bits741 * you right shift the bitContainer by N, then or in742 * the new value into the N upper bits.743 * 3. The bitstream has two bit containers. You can add744 * bits to the second container and merge them into745 * the first container.746 */747 748#define HUF_BITS_IN_CONTAINER (sizeof(size_t) * 8)749 750typedef struct {751 size_t bitContainer[2];752 size_t bitPos[2];753 754 BYTE* startPtr;755 BYTE* ptr;756 BYTE* endPtr;757} HUF_CStream_t;758 759/*! HUF_initCStream():760 * Initializes the bitstream.761 * @returns 0 or an error code.762 */763static size_t HUF_initCStream(HUF_CStream_t* bitC,764 void* startPtr, size_t dstCapacity)765{766 ZSTD_memset(bitC, 0, sizeof(*bitC));767 bitC->startPtr = (BYTE*)startPtr;768 bitC->ptr = bitC->startPtr;769 bitC->endPtr = bitC->startPtr + dstCapacity - sizeof(bitC->bitContainer[0]);770 if (dstCapacity <= sizeof(bitC->bitContainer[0])) return ERROR(dstSize_tooSmall);771 return 0;772}773 774/*! HUF_addBits():775 * Adds the symbol stored in HUF_CElt elt to the bitstream.776 *777 * @param elt The element we're adding. This is a (nbBits, value) pair.778 * See the HUF_CStream_t docs for the format.779 * @param idx Insert into the bitstream at this idx.780 * @param kFast This is a template parameter. If the bitstream is guaranteed781 * to have at least 4 unused bits after this call it may be 1,782 * otherwise it must be 0. HUF_addBits() is faster when fast is set.783 */784FORCE_INLINE_TEMPLATE void HUF_addBits(HUF_CStream_t* bitC, HUF_CElt elt, int idx, int kFast)785{786 assert(idx <= 1);787 assert(HUF_getNbBits(elt) <= HUF_TABLELOG_ABSOLUTEMAX);788 /* This is efficient on x86-64 with BMI2 because shrx789 * only reads the low 6 bits of the register. The compiler790 * knows this and elides the mask. When fast is set,791 * every operation can use the same value loaded from elt.792 */793 bitC->bitContainer[idx] >>= HUF_getNbBits(elt);794 bitC->bitContainer[idx] |= kFast ? HUF_getValueFast(elt) : HUF_getValue(elt);795 /* We only read the low 8 bits of bitC->bitPos[idx] so it796 * doesn't matter that the high bits have noise from the value.797 */798 bitC->bitPos[idx] += HUF_getNbBitsFast(elt);799 assert((bitC->bitPos[idx] & 0xFF) <= HUF_BITS_IN_CONTAINER);800 /* The last 4-bits of elt are dirty if fast is set,801 * so we must not be overwriting bits that have already been802 * inserted into the bit container.803 */804#if DEBUGLEVEL >= 1805 {806 size_t const nbBits = HUF_getNbBits(elt);807 size_t const dirtyBits = nbBits == 0 ? 0 : BIT_highbit32((U32)nbBits) + 1;808 (void)dirtyBits;809 /* Middle bits are 0. */810 assert(((elt >> dirtyBits) << (dirtyBits + nbBits)) == 0);811 /* We didn't overwrite any bits in the bit container. */812 assert(!kFast || (bitC->bitPos[idx] & 0xFF) <= HUF_BITS_IN_CONTAINER);813 (void)dirtyBits;814 }815#endif816}817 818FORCE_INLINE_TEMPLATE void HUF_zeroIndex1(HUF_CStream_t* bitC)819{820 bitC->bitContainer[1] = 0;821 bitC->bitPos[1] = 0;822}823 824/*! HUF_mergeIndex1() :825 * Merges the bit container @ index 1 into the bit container @ index 0826 * and zeros the bit container @ index 1.827 */828FORCE_INLINE_TEMPLATE void HUF_mergeIndex1(HUF_CStream_t* bitC)829{830 assert((bitC->bitPos[1] & 0xFF) < HUF_BITS_IN_CONTAINER);831 bitC->bitContainer[0] >>= (bitC->bitPos[1] & 0xFF);832 bitC->bitContainer[0] |= bitC->bitContainer[1];833 bitC->bitPos[0] += bitC->bitPos[1];834 assert((bitC->bitPos[0] & 0xFF) <= HUF_BITS_IN_CONTAINER);835}836 837/*! HUF_flushBits() :838* Flushes the bits in the bit container @ index 0.839*840* @post bitPos will be < 8.841* @param kFast If kFast is set then we must know a-priori that842* the bit container will not overflow.843*/844FORCE_INLINE_TEMPLATE void HUF_flushBits(HUF_CStream_t* bitC, int kFast)845{846 /* The upper bits of bitPos are noisy, so we must mask by 0xFF. */847 size_t const nbBits = bitC->bitPos[0] & 0xFF;848 size_t const nbBytes = nbBits >> 3;849 /* The top nbBits bits of bitContainer are the ones we need. */850 size_t const bitContainer = bitC->bitContainer[0] >> (HUF_BITS_IN_CONTAINER - nbBits);851 /* Mask bitPos to account for the bytes we consumed. */852 bitC->bitPos[0] &= 7;853 assert(nbBits > 0);854 assert(nbBits <= sizeof(bitC->bitContainer[0]) * 8);855 assert(bitC->ptr <= bitC->endPtr);856 MEM_writeLEST(bitC->ptr, bitContainer);857 bitC->ptr += nbBytes;858 assert(!kFast || bitC->ptr <= bitC->endPtr);859 if (!kFast && bitC->ptr > bitC->endPtr) bitC->ptr = bitC->endPtr;860 /* bitContainer doesn't need to be modified because the leftover861 * bits are already the top bitPos bits. And we don't care about862 * noise in the lower values.863 */864}865 866/*! HUF_endMark()867 * @returns The Huffman stream end mark: A 1-bit value = 1.868 */869static HUF_CElt HUF_endMark(void)870{871 HUF_CElt endMark;872 HUF_setNbBits(&endMark, 1);873 HUF_setValue(&endMark, 1);874 return endMark;875}876 877/*! HUF_closeCStream() :878 * @return Size of CStream, in bytes,879 * or 0 if it could not fit into dstBuffer */880static size_t HUF_closeCStream(HUF_CStream_t* bitC)881{882 HUF_addBits(bitC, HUF_endMark(), /* idx */ 0, /* kFast */ 0);883 HUF_flushBits(bitC, /* kFast */ 0);884 {885 size_t const nbBits = bitC->bitPos[0] & 0xFF;886 if (bitC->ptr >= bitC->endPtr) return 0; /* overflow detected */887 return (bitC->ptr - bitC->startPtr) + (nbBits > 0);888 }889}890 891FORCE_INLINE_TEMPLATE void892HUF_encodeSymbol(HUF_CStream_t* bitCPtr, U32 symbol, const HUF_CElt* CTable, int idx, int fast)893{894 HUF_addBits(bitCPtr, CTable[symbol], idx, fast);895}896 897FORCE_INLINE_TEMPLATE void898HUF_compress1X_usingCTable_internal_body_loop(HUF_CStream_t* bitC,899 const BYTE* ip, size_t srcSize,900 const HUF_CElt* ct,901 int kUnroll, int kFastFlush, int kLastFast)902{903 /* Join to kUnroll */904 int n = (int)srcSize;905 int rem = n % kUnroll;906 if (rem > 0) {907 for (; rem > 0; --rem) {908 HUF_encodeSymbol(bitC, ip[--n], ct, 0, /* fast */ 0);909 }910 HUF_flushBits(bitC, kFastFlush);911 }912 assert(n % kUnroll == 0);913 914 /* Join to 2 * kUnroll */915 if (n % (2 * kUnroll)) {916 int u;917 for (u = 1; u < kUnroll; ++u) {918 HUF_encodeSymbol(bitC, ip[n - u], ct, 0, 1);919 }920 HUF_encodeSymbol(bitC, ip[n - kUnroll], ct, 0, kLastFast);921 HUF_flushBits(bitC, kFastFlush);922 n -= kUnroll;923 }924 assert(n % (2 * kUnroll) == 0);925 926 for (; n>0; n-= 2 * kUnroll) {927 /* Encode kUnroll symbols into the bitstream @ index 0. */928 int u;929 for (u = 1; u < kUnroll; ++u) {930 HUF_encodeSymbol(bitC, ip[n - u], ct, /* idx */ 0, /* fast */ 1);931 }932 HUF_encodeSymbol(bitC, ip[n - kUnroll], ct, /* idx */ 0, /* fast */ kLastFast);933 HUF_flushBits(bitC, kFastFlush);934 /* Encode kUnroll symbols into the bitstream @ index 1.935 * This allows us to start filling the bit container936 * without any data dependencies.937 */938 HUF_zeroIndex1(bitC);939 for (u = 1; u < kUnroll; ++u) {940 HUF_encodeSymbol(bitC, ip[n - kUnroll - u], ct, /* idx */ 1, /* fast */ 1);941 }942 HUF_encodeSymbol(bitC, ip[n - kUnroll - kUnroll], ct, /* idx */ 1, /* fast */ kLastFast);943 /* Merge bitstream @ index 1 into the bitstream @ index 0 */944 HUF_mergeIndex1(bitC);945 HUF_flushBits(bitC, kFastFlush);946 }947 assert(n == 0);948 949}950 951/*952 * Returns a tight upper bound on the output space needed by Huffman953 * with 8 bytes buffer to handle over-writes. If the output is at least954 * this large we don't need to do bounds checks during Huffman encoding.955 */956static size_t HUF_tightCompressBound(size_t srcSize, size_t tableLog)957{958 return ((srcSize * tableLog) >> 3) + 8;959}960 961 962FORCE_INLINE_TEMPLATE size_t963HUF_compress1X_usingCTable_internal_body(void* dst, size_t dstSize,964 const void* src, size_t srcSize,965 const HUF_CElt* CTable)966{967 U32 const tableLog = (U32)CTable[0];968 HUF_CElt const* ct = CTable + 1;969 const BYTE* ip = (const BYTE*) src;970 BYTE* const ostart = (BYTE*)dst;971 BYTE* const oend = ostart + dstSize;972 BYTE* op = ostart;973 HUF_CStream_t bitC;974 975 /* init */976 if (dstSize < 8) return 0; /* not enough space to compress */977 { size_t const initErr = HUF_initCStream(&bitC, op, (size_t)(oend-op));978 if (HUF_isError(initErr)) return 0; }979 980 if (dstSize < HUF_tightCompressBound(srcSize, (size_t)tableLog) || tableLog > 11)981 HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ MEM_32bits() ? 2 : 4, /* kFast */ 0, /* kLastFast */ 0);982 else {983 if (MEM_32bits()) {984 switch (tableLog) {985 case 11:986 HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 2, /* kFastFlush */ 1, /* kLastFast */ 0);987 break;988 case 10: ZSTD_FALLTHROUGH;989 case 9: ZSTD_FALLTHROUGH;990 case 8:991 HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 2, /* kFastFlush */ 1, /* kLastFast */ 1);992 break;993 case 7: ZSTD_FALLTHROUGH;994 default:995 HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 3, /* kFastFlush */ 1, /* kLastFast */ 1);996 break;997 }998 } else {999 switch (tableLog) {1000 case 11:1001 HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 5, /* kFastFlush */ 1, /* kLastFast */ 0);1002 break;1003 case 10:1004 HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 5, /* kFastFlush */ 1, /* kLastFast */ 1);1005 break;1006 case 9:1007 HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 6, /* kFastFlush */ 1, /* kLastFast */ 0);1008 break;1009 case 8:1010 HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 7, /* kFastFlush */ 1, /* kLastFast */ 0);1011 break;1012 case 7:1013 HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 8, /* kFastFlush */ 1, /* kLastFast */ 0);1014 break;1015 case 6: ZSTD_FALLTHROUGH;1016 default:1017 HUF_compress1X_usingCTable_internal_body_loop(&bitC, ip, srcSize, ct, /* kUnroll */ 9, /* kFastFlush */ 1, /* kLastFast */ 1);1018 break;1019 }1020 }1021 }1022 assert(bitC.ptr <= bitC.endPtr);1023 1024 return HUF_closeCStream(&bitC);1025}1026 1027#if DYNAMIC_BMI21028 1029static BMI2_TARGET_ATTRIBUTE size_t1030HUF_compress1X_usingCTable_internal_bmi2(void* dst, size_t dstSize,1031 const void* src, size_t srcSize,1032 const HUF_CElt* CTable)1033{1034 return HUF_compress1X_usingCTable_internal_body(dst, dstSize, src, srcSize, CTable);1035}1036 1037static size_t1038HUF_compress1X_usingCTable_internal_default(void* dst, size_t dstSize,1039 const void* src, size_t srcSize,1040 const HUF_CElt* CTable)1041{1042 return HUF_compress1X_usingCTable_internal_body(dst, dstSize, src, srcSize, CTable);1043}1044 1045static size_t1046HUF_compress1X_usingCTable_internal(void* dst, size_t dstSize,1047 const void* src, size_t srcSize,1048 const HUF_CElt* CTable, const int bmi2)1049{1050 if (bmi2) {1051 return HUF_compress1X_usingCTable_internal_bmi2(dst, dstSize, src, srcSize, CTable);1052 }1053 return HUF_compress1X_usingCTable_internal_default(dst, dstSize, src, srcSize, CTable);1054}1055 1056#else1057 1058static size_t1059HUF_compress1X_usingCTable_internal(void* dst, size_t dstSize,1060 const void* src, size_t srcSize,1061 const HUF_CElt* CTable, const int bmi2)1062{1063 (void)bmi2;1064 return HUF_compress1X_usingCTable_internal_body(dst, dstSize, src, srcSize, CTable);1065}1066 1067#endif1068 1069size_t HUF_compress1X_usingCTable(void* dst, size_t dstSize, const void* src, size_t srcSize, const HUF_CElt* CTable)1070{1071 return HUF_compress1X_usingCTable_bmi2(dst, dstSize, src, srcSize, CTable, /* bmi2 */ 0);1072}1073 1074size_t HUF_compress1X_usingCTable_bmi2(void* dst, size_t dstSize, const void* src, size_t srcSize, const HUF_CElt* CTable, int bmi2)1075{1076 return HUF_compress1X_usingCTable_internal(dst, dstSize, src, srcSize, CTable, bmi2);1077}1078 1079static size_t1080HUF_compress4X_usingCTable_internal(void* dst, size_t dstSize,1081 const void* src, size_t srcSize,1082 const HUF_CElt* CTable, int bmi2)1083{1084 size_t const segmentSize = (srcSize+3)/4; /* first 3 segments */1085 const BYTE* ip = (const BYTE*) src;1086 const BYTE* const iend = ip + srcSize;1087 BYTE* const ostart = (BYTE*) dst;1088 BYTE* const oend = ostart + dstSize;1089 BYTE* op = ostart;1090 1091 if (dstSize < 6 + 1 + 1 + 1 + 8) return 0; /* minimum space to compress successfully */1092 if (srcSize < 12) return 0; /* no saving possible : too small input */1093 op += 6; /* jumpTable */1094 1095 assert(op <= oend);1096 { CHECK_V_F(cSize, HUF_compress1X_usingCTable_internal(op, (size_t)(oend-op), ip, segmentSize, CTable, bmi2) );1097 if (cSize == 0 || cSize > 65535) return 0;1098 MEM_writeLE16(ostart, (U16)cSize);1099 op += cSize;1100 }1101 1102 ip += segmentSize;1103 assert(op <= oend);1104 { CHECK_V_F(cSize, HUF_compress1X_usingCTable_internal(op, (size_t)(oend-op), ip, segmentSize, CTable, bmi2) );1105 if (cSize == 0 || cSize > 65535) return 0;1106 MEM_writeLE16(ostart+2, (U16)cSize);1107 op += cSize;1108 }1109 1110 ip += segmentSize;1111 assert(op <= oend);1112 { CHECK_V_F(cSize, HUF_compress1X_usingCTable_internal(op, (size_t)(oend-op), ip, segmentSize, CTable, bmi2) );1113 if (cSize == 0 || cSize > 65535) return 0;1114 MEM_writeLE16(ostart+4, (U16)cSize);1115 op += cSize;1116 }1117 1118 ip += segmentSize;1119 assert(op <= oend);1120 assert(ip <= iend);1121 { CHECK_V_F(cSize, HUF_compress1X_usingCTable_internal(op, (size_t)(oend-op), ip, (size_t)(iend-ip), CTable, bmi2) );1122 if (cSize == 0 || cSize > 65535) return 0;1123 op += cSize;1124 }1125 1126 return (size_t)(op-ostart);1127}1128 1129size_t HUF_compress4X_usingCTable(void* dst, size_t dstSize, const void* src, size_t srcSize, const HUF_CElt* CTable)1130{1131 return HUF_compress4X_usingCTable_bmi2(dst, dstSize, src, srcSize, CTable, /* bmi2 */ 0);1132}1133 1134size_t HUF_compress4X_usingCTable_bmi2(void* dst, size_t dstSize, const void* src, size_t srcSize, const HUF_CElt* CTable, int bmi2)1135{1136 return HUF_compress4X_usingCTable_internal(dst, dstSize, src, srcSize, CTable, bmi2);1137}1138 1139typedef enum { HUF_singleStream, HUF_fourStreams } HUF_nbStreams_e;1140 1141static size_t HUF_compressCTable_internal(1142 BYTE* const ostart, BYTE* op, BYTE* const oend,1143 const void* src, size_t srcSize,1144 HUF_nbStreams_e nbStreams, const HUF_CElt* CTable, const int bmi2)1145{1146 size_t const cSize = (nbStreams==HUF_singleStream) ?1147 HUF_compress1X_usingCTable_internal(op, (size_t)(oend - op), src, srcSize, CTable, bmi2) :1148 HUF_compress4X_usingCTable_internal(op, (size_t)(oend - op), src, srcSize, CTable, bmi2);1149 if (HUF_isError(cSize)) { return cSize; }1150 if (cSize==0) { return 0; } /* uncompressible */1151 op += cSize;1152 /* check compressibility */1153 assert(op >= ostart);1154 if ((size_t)(op-ostart) >= srcSize-1) { return 0; }1155 return (size_t)(op-ostart);1156}1157 1158typedef struct {1159 unsigned count[HUF_SYMBOLVALUE_MAX + 1];1160 HUF_CElt CTable[HUF_CTABLE_SIZE_ST(HUF_SYMBOLVALUE_MAX)];1161 union {1162 HUF_buildCTable_wksp_tables buildCTable_wksp;1163 HUF_WriteCTableWksp writeCTable_wksp;1164 U32 hist_wksp[HIST_WKSP_SIZE_U32];1165 } wksps;1166} HUF_compress_tables_t;1167 1168#define SUSPECT_INCOMPRESSIBLE_SAMPLE_SIZE 40961169#define SUSPECT_INCOMPRESSIBLE_SAMPLE_RATIO 10 /* Must be >= 2 */1170 1171/* HUF_compress_internal() :1172 * `workSpace_align4` must be aligned on 4-bytes boundaries,1173 * and occupies the same space as a table of HUF_WORKSPACE_SIZE_U64 unsigned */1174static size_t1175HUF_compress_internal (void* dst, size_t dstSize,1176 const void* src, size_t srcSize,1177 unsigned maxSymbolValue, unsigned huffLog,1178 HUF_nbStreams_e nbStreams,1179 void* workSpace, size_t wkspSize,1180 HUF_CElt* oldHufTable, HUF_repeat* repeat, int preferRepeat,1181 const int bmi2, unsigned suspectUncompressible)1182{1183 HUF_compress_tables_t* const table = (HUF_compress_tables_t*)HUF_alignUpWorkspace(workSpace, &wkspSize, ZSTD_ALIGNOF(size_t));1184 BYTE* const ostart = (BYTE*)dst;1185 BYTE* const oend = ostart + dstSize;1186 BYTE* op = ostart;1187 1188 HUF_STATIC_ASSERT(sizeof(*table) + HUF_WORKSPACE_MAX_ALIGNMENT <= HUF_WORKSPACE_SIZE);1189 1190 /* checks & inits */1191 if (wkspSize < sizeof(*table)) return ERROR(workSpace_tooSmall);1192 if (!srcSize) return 0; /* Uncompressed */1193 if (!dstSize) return 0; /* cannot fit anything within dst budget */1194 if (srcSize > HUF_BLOCKSIZE_MAX) return ERROR(srcSize_wrong); /* current block size limit */1195 if (huffLog > HUF_TABLELOG_MAX) return ERROR(tableLog_tooLarge);1196 if (maxSymbolValue > HUF_SYMBOLVALUE_MAX) return ERROR(maxSymbolValue_tooLarge);1197 if (!maxSymbolValue) maxSymbolValue = HUF_SYMBOLVALUE_MAX;1198 if (!huffLog) huffLog = HUF_TABLELOG_DEFAULT;1199 1200 /* Heuristic : If old table is valid, use it for small inputs */1201 if (preferRepeat && repeat && *repeat == HUF_repeat_valid) {1202 return HUF_compressCTable_internal(ostart, op, oend,1203 src, srcSize,1204 nbStreams, oldHufTable, bmi2);1205 }1206 1207 /* If uncompressible data is suspected, do a smaller sampling first */1208 DEBUG_STATIC_ASSERT(SUSPECT_INCOMPRESSIBLE_SAMPLE_RATIO >= 2);1209 if (suspectUncompressible && srcSize >= (SUSPECT_INCOMPRESSIBLE_SAMPLE_SIZE * SUSPECT_INCOMPRESSIBLE_SAMPLE_RATIO)) {1210 size_t largestTotal = 0;1211 { unsigned maxSymbolValueBegin = maxSymbolValue;1212 CHECK_V_F(largestBegin, HIST_count_simple (table->count, &maxSymbolValueBegin, (const BYTE*)src, SUSPECT_INCOMPRESSIBLE_SAMPLE_SIZE) );1213 largestTotal += largestBegin;1214 }1215 { unsigned maxSymbolValueEnd = maxSymbolValue;1216 CHECK_V_F(largestEnd, HIST_count_simple (table->count, &maxSymbolValueEnd, (const BYTE*)src + srcSize - SUSPECT_INCOMPRESSIBLE_SAMPLE_SIZE, SUSPECT_INCOMPRESSIBLE_SAMPLE_SIZE) );1217 largestTotal += largestEnd;1218 }1219 if (largestTotal <= ((2 * SUSPECT_INCOMPRESSIBLE_SAMPLE_SIZE) >> 7)+4) return 0; /* heuristic : probably not compressible enough */1220 }1221 1222 /* Scan input and build symbol stats */1223 { CHECK_V_F(largest, HIST_count_wksp (table->count, &maxSymbolValue, (const BYTE*)src, srcSize, table->wksps.hist_wksp, sizeof(table->wksps.hist_wksp)) );1224 if (largest == srcSize) { *ostart = ((const BYTE*)src)[0]; return 1; } /* single symbol, rle */1225 if (largest <= (srcSize >> 7)+4) return 0; /* heuristic : probably not compressible enough */1226 }1227 1228 /* Check validity of previous table */1229 if ( repeat1230 && *repeat == HUF_repeat_check1231 && !HUF_validateCTable(oldHufTable, table->count, maxSymbolValue)) {1232 *repeat = HUF_repeat_none;1233 }1234 /* Heuristic : use existing table for small inputs */1235 if (preferRepeat && repeat && *repeat != HUF_repeat_none) {1236 return HUF_compressCTable_internal(ostart, op, oend,1237 src, srcSize,1238 nbStreams, oldHufTable, bmi2);1239 }1240 1241 /* Build Huffman Tree */1242 huffLog = HUF_optimalTableLog(huffLog, srcSize, maxSymbolValue);1243 { size_t const maxBits = HUF_buildCTable_wksp(table->CTable, table->count,1244 maxSymbolValue, huffLog,1245 &table->wksps.buildCTable_wksp, sizeof(table->wksps.buildCTable_wksp));1246 CHECK_F(maxBits);1247 huffLog = (U32)maxBits;1248 }1249 /* Zero unused symbols in CTable, so we can check it for validity */1250 {1251 size_t const ctableSize = HUF_CTABLE_SIZE_ST(maxSymbolValue);1252 size_t const unusedSize = sizeof(table->CTable) - ctableSize * sizeof(HUF_CElt);1253 ZSTD_memset(table->CTable + ctableSize, 0, unusedSize);1254 }1255 1256 /* Write table description header */1257 { CHECK_V_F(hSize, HUF_writeCTable_wksp(op, dstSize, table->CTable, maxSymbolValue, huffLog,1258 &table->wksps.writeCTable_wksp, sizeof(table->wksps.writeCTable_wksp)) );1259 /* Check if using previous huffman table is beneficial */1260 if (repeat && *repeat != HUF_repeat_none) {1261 size_t const oldSize = HUF_estimateCompressedSize(oldHufTable, table->count, maxSymbolValue);1262 size_t const newSize = HUF_estimateCompressedSize(table->CTable, table->count, maxSymbolValue);1263 if (oldSize <= hSize + newSize || hSize + 12 >= srcSize) {1264 return HUF_compressCTable_internal(ostart, op, oend,1265 src, srcSize,1266 nbStreams, oldHufTable, bmi2);1267 } }1268 1269 /* Use the new huffman table */1270 if (hSize + 12ul >= srcSize) { return 0; }1271 op += hSize;1272 if (repeat) { *repeat = HUF_repeat_none; }1273 if (oldHufTable)1274 ZSTD_memcpy(oldHufTable, table->CTable, sizeof(table->CTable)); /* Save new table */1275 }1276 return HUF_compressCTable_internal(ostart, op, oend,1277 src, srcSize,1278 nbStreams, table->CTable, bmi2);1279}1280 1281 1282size_t HUF_compress1X_wksp (void* dst, size_t dstSize,1283 const void* src, size_t srcSize,1284 unsigned maxSymbolValue, unsigned huffLog,1285 void* workSpace, size_t wkspSize)1286{1287 return HUF_compress_internal(dst, dstSize, src, srcSize,1288 maxSymbolValue, huffLog, HUF_singleStream,1289 workSpace, wkspSize,1290 NULL, NULL, 0, 0 /*bmi2*/, 0);1291}1292 1293size_t HUF_compress1X_repeat (void* dst, size_t dstSize,1294 const void* src, size_t srcSize,1295 unsigned maxSymbolValue, unsigned huffLog,1296 void* workSpace, size_t wkspSize,1297 HUF_CElt* hufTable, HUF_repeat* repeat, int preferRepeat,1298 int bmi2, unsigned suspectUncompressible)1299{1300 return HUF_compress_internal(dst, dstSize, src, srcSize,1301 maxSymbolValue, huffLog, HUF_singleStream,1302 workSpace, wkspSize, hufTable,1303 repeat, preferRepeat, bmi2, suspectUncompressible);1304}1305 1306/* HUF_compress4X_repeat():1307 * compress input using 4 streams.1308 * provide workspace to generate compression tables */1309size_t HUF_compress4X_wksp (void* dst, size_t dstSize,1310 const void* src, size_t srcSize,1311 unsigned maxSymbolValue, unsigned huffLog,1312 void* workSpace, size_t wkspSize)1313{1314 return HUF_compress_internal(dst, dstSize, src, srcSize,1315 maxSymbolValue, huffLog, HUF_fourStreams,1316 workSpace, wkspSize,1317 NULL, NULL, 0, 0 /*bmi2*/, 0);1318}1319 1320/* HUF_compress4X_repeat():1321 * compress input using 4 streams.1322 * consider skipping quickly1323 * re-use an existing huffman compression table */1324size_t HUF_compress4X_repeat (void* dst, size_t dstSize,1325 const void* src, size_t srcSize,1326 unsigned maxSymbolValue, unsigned huffLog,1327 void* workSpace, size_t wkspSize,1328 HUF_CElt* hufTable, HUF_repeat* repeat, int preferRepeat, int bmi2, unsigned suspectUncompressible)1329{1330 return HUF_compress_internal(dst, dstSize, src, srcSize,1331 maxSymbolValue, huffLog, HUF_fourStreams,1332 workSpace, wkspSize,1333 hufTable, repeat, preferRepeat, bmi2, suspectUncompressible);1334}1335 1336