1 /* ******************************************************************
2 * Huffman encoder, part of New Generation Entropy library
3 * Copyright (c) Yann Collet, Facebook, Inc.
4 *
5 * You can contact the author at :
6 * - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy
7 * - Public forum : https://groups.google.com/forum/#!forum/lz4c
8 *
9 * This source code is licensed under both the BSD-style license (found in the
10 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
11 * 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 specifics
17 ****************************************************************/
18
19
20 /* **************************************************************
21 * Includes
22 ****************************************************************/
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_ONLY
30 #include "../common/huf.h"
31 #include "../common/error_private.h"
32
33
34 /* **************************************************************
35 * Error Management
36 ****************************************************************/
37 #define HUF_isError ERR_isError
38 #define HUF_STATIC_ASSERT(c) DEBUG_STATIC_ASSERT(c) /* use only *after* variable declarations */
39
40
41 /* **************************************************************
42 * Utils
43 ****************************************************************/
44 unsigned 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 compression
52 *********************************************************/
53 #define HUF_WORKSPACE_MAX_ALIGNMENT 8
54
55 static 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 6
81
82 typedef 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
89 static 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
128 static size_t HUF_getNbBits(HUF_CElt elt)
129 {
130 return elt & 0xFF;
131 }
132
133 static size_t HUF_getNbBitsFast(HUF_CElt elt)
134 {
135 return elt;
136 }
137
138 static size_t HUF_getValue(HUF_CElt elt)
139 {
140 return elt & ~0xFF;
141 }
142
143 static size_t HUF_getValueFast(HUF_CElt elt)
144 {
145 return elt;
146 }
147
148 static void HUF_setNbBits(HUF_CElt* elt, size_t nbBits)
149 {
150 assert(nbBits <= HUF_TABLELOG_ABSOLUTEMAX);
151 *elt = nbBits;
152 }
153
154 static 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
163 typedef 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
169 size_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 */
210 size_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
218 size_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
270 U32 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
278 typedef 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 adjusts
290 * 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 tree
300 * may not respect. After this function the Huffman tree will
301 * respect maxNbBits.
302 * @return The maximum number of bits of the Huffman tree after adjustment,
303 * necessarily no more than maxNbBits.
304 */
305 static 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 is
318 * 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^maxNbBits
331 * 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 we
352 * 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 is
360 * 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 now
387 * 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 them
402 * to rank 1. There's guaranteed to be enough rank 0 symbols because
403 * 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
427 typedef struct {
428 U16 base;
429 U16 curr;
430 } rankPos;
431
432 typedef nodeElt huffNodeTable[HUF_CTABLE_WORKSPACE_SIZE_U32];
433
434 /* Number of buckets available for HUF_sort() */
435 #define RANK_POSITION_TABLE_SIZE 192
436
437 typedef 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 distinct
444 * 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 32
451 #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 of
455 * RANK_POSITION_DISTINCT_COUNT_CUTOFF for explanation of bucketing strategy.
456 */
457 static U32 HUF_getIndex(U32 const count) {
458 return (count < RANK_POSITION_DISTINCT_COUNT_CUTOFF)
459 ? count
460 : BIT_highbit32(count) + RANK_POSITION_LOG_BUCKETS_BEGIN;
461 }
462
463 /* Helper swap function for HUF_quickSortPartition() */
464 static 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 */
471 MEM_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 */
482 HINT_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. */
498 static int HUF_quickSortPartition(nodeElt arr[], int const low, int const high) {
499 /* Simply select rightmost element as pivot. "Better" selectors like
500 * 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 calls
516 * to reduce worst case callstack size.
517 */
518 static 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 */
547 static 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 where
555 * 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 */
607 static 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 */
653 static 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
677 size_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
707 size_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
718 int 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
728 size_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 is
734 * the pair (nbBits, value) in the format:
735 * format:
736 * - Bits [0, 4) = nbBits
737 * - Bits [4, 64 - nbBits) = 0
738 * - Bits [64 - nbBits, 64) = value
739 * 2. The bitContainer is built from the upper bits and
740 * right shifted. E.g. to add a new value of N bits
741 * you right shift the bitContainer by N, then or in
742 * the new value into the N upper bits.
743 * 3. The bitstream has two bit containers. You can add
744 * bits to the second container and merge them into
745 * the first container.
746 */
747
748 #define HUF_BITS_IN_CONTAINER (sizeof(size_t) * 8)
749
750 typedef 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 */
763 static 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 guaranteed
781 * 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 */
784 FORCE_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 shrx
789 * only reads the low 6 bits of the register. The compiler
790 * 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 it
796 * 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 been
802 * inserted into the bit container.
803 */
804 #if DEBUGLEVEL >= 1
805 {
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 #endif
816 }
817
818 FORCE_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 0
826 * and zeros the bit container @ index 1.
827 */
828 FORCE_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 that
842 * the bit container will not overflow.
843 */
844 FORCE_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 leftover
861 * bits are already the top bitPos bits. And we don't care about
862 * noise in the lower values.
863 */
864 }
865
866 /*! HUF_endMark()
867 * @returns The Huffman stream end mark: A 1-bit value = 1.
868 */
869 static 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 */
880 static 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
891 FORCE_INLINE_TEMPLATE void
892 HUF_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
897 FORCE_INLINE_TEMPLATE void
898 HUF_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 container
936 * 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 Huffman
953 * with 8 bytes buffer to handle over-writes. If the output is at least
954 * this large we don't need to do bounds checks during Huffman encoding.
955 */
956 static size_t HUF_tightCompressBound(size_t srcSize, size_t tableLog)
957 {
958 return ((srcSize * tableLog) >> 3) + 8;
959 }
960
961
962 FORCE_INLINE_TEMPLATE size_t
963 HUF_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_BMI2
1028
1029 static BMI2_TARGET_ATTRIBUTE size_t
1030 HUF_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
1037 static size_t
1038 HUF_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
1045 static size_t
1046 HUF_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 #else
1057
1058 static size_t
1059 HUF_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 #endif
1068
1069 size_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
1074 size_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
1079 static size_t
1080 HUF_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
1129 size_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
1134 size_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
1139 typedef enum { HUF_singleStream, HUF_fourStreams } HUF_nbStreams_e;
1140
1141 static 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
1158 typedef 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 4096
1169 #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 */
1174 static size_t
1175 HUF_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 ( repeat
1230 && *repeat == HUF_repeat_check
1231 && !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
1282 size_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
1293 size_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 */
1309 size_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 quickly
1323 * re-use an existing huffman compression table */
1324 size_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
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.