tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1/*
2 * Huffman encoder, part of New Generation Entropy library
3 * Copyright (C) 2013-2016, Yann Collet.
4 *
5 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are
9 * met:
10 *
11 * * Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * * Redistributions in binary form must reproduce the above
14 * copyright notice, this list of conditions and the following disclaimer
15 * in the documentation and/or other materials provided with the
16 * distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 *
30 * This program is free software; you can redistribute it and/or modify it under
31 * the terms of the GNU General Public License version 2 as published by the
32 * Free Software Foundation. This program is dual-licensed; you may select
33 * either version 2 of the GNU General Public License ("GPL") or BSD license
34 * ("BSD").
35 *
36 * You can contact the author at :
37 * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
38 */
39
40/* **************************************************************
41* Includes
42****************************************************************/
43#include "bitstream.h"
44#include "fse.h" /* header compression */
45#include "huf.h"
46#include <linux/kernel.h>
47#include <linux/string.h> /* memcpy, memset */
48
49/* **************************************************************
50* Error Management
51****************************************************************/
52#define HUF_STATIC_ASSERT(c) \
53 { \
54 enum { HUF_static_assert = 1 / (int)(!!(c)) }; \
55 } /* use only *after* variable declarations */
56#define CHECK_V_F(e, f) \
57 size_t const e = f; \
58 if (ERR_isError(e)) \
59 return f
60#define CHECK_F(f) \
61 { \
62 CHECK_V_F(_var_err__, f); \
63 }
64
65/* **************************************************************
66* Utils
67****************************************************************/
68unsigned HUF_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue)
69{
70 return FSE_optimalTableLog_internal(maxTableLog, srcSize, maxSymbolValue, 1);
71}
72
73/* *******************************************************
74* HUF : Huffman block compression
75*********************************************************/
76/* HUF_compressWeights() :
77 * Same as FSE_compress(), but dedicated to huff0's weights compression.
78 * The use case needs much less stack memory.
79 * Note : all elements within weightTable are supposed to be <= HUF_TABLELOG_MAX.
80 */
81#define MAX_FSE_TABLELOG_FOR_HUFF_HEADER 6
82size_t HUF_compressWeights_wksp(void *dst, size_t dstSize, const void *weightTable, size_t wtSize, void *workspace, size_t workspaceSize)
83{
84 BYTE *const ostart = (BYTE *)dst;
85 BYTE *op = ostart;
86 BYTE *const oend = ostart + dstSize;
87
88 U32 maxSymbolValue = HUF_TABLELOG_MAX;
89 U32 tableLog = MAX_FSE_TABLELOG_FOR_HUFF_HEADER;
90
91 FSE_CTable *CTable;
92 U32 *count;
93 S16 *norm;
94 size_t spaceUsed32 = 0;
95
96 HUF_STATIC_ASSERT(sizeof(FSE_CTable) == sizeof(U32));
97
98 CTable = (FSE_CTable *)((U32 *)workspace + spaceUsed32);
99 spaceUsed32 += FSE_CTABLE_SIZE_U32(MAX_FSE_TABLELOG_FOR_HUFF_HEADER, HUF_TABLELOG_MAX);
100 count = (U32 *)workspace + spaceUsed32;
101 spaceUsed32 += HUF_TABLELOG_MAX + 1;
102 norm = (S16 *)((U32 *)workspace + spaceUsed32);
103 spaceUsed32 += ALIGN(sizeof(S16) * (HUF_TABLELOG_MAX + 1), sizeof(U32)) >> 2;
104
105 if ((spaceUsed32 << 2) > workspaceSize)
106 return ERROR(tableLog_tooLarge);
107 workspace = (U32 *)workspace + spaceUsed32;
108 workspaceSize -= (spaceUsed32 << 2);
109
110 /* init conditions */
111 if (wtSize <= 1)
112 return 0; /* Not compressible */
113
114 /* Scan input and build symbol stats */
115 {
116 CHECK_V_F(maxCount, FSE_count_simple(count, &maxSymbolValue, weightTable, wtSize));
117 if (maxCount == wtSize)
118 return 1; /* only a single symbol in src : rle */
119 if (maxCount == 1)
120 return 0; /* each symbol present maximum once => not compressible */
121 }
122
123 tableLog = FSE_optimalTableLog(tableLog, wtSize, maxSymbolValue);
124 CHECK_F(FSE_normalizeCount(norm, tableLog, count, wtSize, maxSymbolValue));
125
126 /* Write table description header */
127 {
128 CHECK_V_F(hSize, FSE_writeNCount(op, oend - op, norm, maxSymbolValue, tableLog));
129 op += hSize;
130 }
131
132 /* Compress */
133 CHECK_F(FSE_buildCTable_wksp(CTable, norm, maxSymbolValue, tableLog, workspace, workspaceSize));
134 {
135 CHECK_V_F(cSize, FSE_compress_usingCTable(op, oend - op, weightTable, wtSize, CTable));
136 if (cSize == 0)
137 return 0; /* not enough space for compressed data */
138 op += cSize;
139 }
140
141 return op - ostart;
142}
143
144struct HUF_CElt_s {
145 U16 val;
146 BYTE nbBits;
147}; /* typedef'd to HUF_CElt within "huf.h" */
148
149/*! HUF_writeCTable_wksp() :
150 `CTable` : Huffman tree to save, using huf representation.
151 @return : size of saved CTable */
152size_t HUF_writeCTable_wksp(void *dst, size_t maxDstSize, const HUF_CElt *CTable, U32 maxSymbolValue, U32 huffLog, void *workspace, size_t workspaceSize)
153{
154 BYTE *op = (BYTE *)dst;
155 U32 n;
156
157 BYTE *bitsToWeight;
158 BYTE *huffWeight;
159 size_t spaceUsed32 = 0;
160
161 bitsToWeight = (BYTE *)((U32 *)workspace + spaceUsed32);
162 spaceUsed32 += ALIGN(HUF_TABLELOG_MAX + 1, sizeof(U32)) >> 2;
163 huffWeight = (BYTE *)((U32 *)workspace + spaceUsed32);
164 spaceUsed32 += ALIGN(HUF_SYMBOLVALUE_MAX, sizeof(U32)) >> 2;
165
166 if ((spaceUsed32 << 2) > workspaceSize)
167 return ERROR(tableLog_tooLarge);
168 workspace = (U32 *)workspace + spaceUsed32;
169 workspaceSize -= (spaceUsed32 << 2);
170
171 /* check conditions */
172 if (maxSymbolValue > HUF_SYMBOLVALUE_MAX)
173 return ERROR(maxSymbolValue_tooLarge);
174
175 /* convert to weight */
176 bitsToWeight[0] = 0;
177 for (n = 1; n < huffLog + 1; n++)
178 bitsToWeight[n] = (BYTE)(huffLog + 1 - n);
179 for (n = 0; n < maxSymbolValue; n++)
180 huffWeight[n] = bitsToWeight[CTable[n].nbBits];
181
182 /* attempt weights compression by FSE */
183 {
184 CHECK_V_F(hSize, HUF_compressWeights_wksp(op + 1, maxDstSize - 1, huffWeight, maxSymbolValue, workspace, workspaceSize));
185 if ((hSize > 1) & (hSize < maxSymbolValue / 2)) { /* FSE compressed */
186 op[0] = (BYTE)hSize;
187 return hSize + 1;
188 }
189 }
190
191 /* write raw values as 4-bits (max : 15) */
192 if (maxSymbolValue > (256 - 128))
193 return ERROR(GENERIC); /* should not happen : likely means source cannot be compressed */
194 if (((maxSymbolValue + 1) / 2) + 1 > maxDstSize)
195 return ERROR(dstSize_tooSmall); /* not enough space within dst buffer */
196 op[0] = (BYTE)(128 /*special case*/ + (maxSymbolValue - 1));
197 huffWeight[maxSymbolValue] = 0; /* to be sure it doesn't cause msan issue in final combination */
198 for (n = 0; n < maxSymbolValue; n += 2)
199 op[(n / 2) + 1] = (BYTE)((huffWeight[n] << 4) + huffWeight[n + 1]);
200 return ((maxSymbolValue + 1) / 2) + 1;
201}
202
203size_t HUF_readCTable_wksp(HUF_CElt *CTable, U32 maxSymbolValue, const void *src, size_t srcSize, void *workspace, size_t workspaceSize)
204{
205 U32 *rankVal;
206 BYTE *huffWeight;
207 U32 tableLog = 0;
208 U32 nbSymbols = 0;
209 size_t readSize;
210 size_t spaceUsed32 = 0;
211
212 rankVal = (U32 *)workspace + spaceUsed32;
213 spaceUsed32 += HUF_TABLELOG_ABSOLUTEMAX + 1;
214 huffWeight = (BYTE *)((U32 *)workspace + spaceUsed32);
215 spaceUsed32 += ALIGN(HUF_SYMBOLVALUE_MAX + 1, sizeof(U32)) >> 2;
216
217 if ((spaceUsed32 << 2) > workspaceSize)
218 return ERROR(tableLog_tooLarge);
219 workspace = (U32 *)workspace + spaceUsed32;
220 workspaceSize -= (spaceUsed32 << 2);
221
222 /* get symbol weights */
223 readSize = HUF_readStats_wksp(huffWeight, HUF_SYMBOLVALUE_MAX + 1, rankVal, &nbSymbols, &tableLog, src, srcSize, workspace, workspaceSize);
224 if (ERR_isError(readSize))
225 return readSize;
226
227 /* check result */
228 if (tableLog > HUF_TABLELOG_MAX)
229 return ERROR(tableLog_tooLarge);
230 if (nbSymbols > maxSymbolValue + 1)
231 return ERROR(maxSymbolValue_tooSmall);
232
233 /* Prepare base value per rank */
234 {
235 U32 n, nextRankStart = 0;
236 for (n = 1; n <= tableLog; n++) {
237 U32 curr = nextRankStart;
238 nextRankStart += (rankVal[n] << (n - 1));
239 rankVal[n] = curr;
240 }
241 }
242
243 /* fill nbBits */
244 {
245 U32 n;
246 for (n = 0; n < nbSymbols; n++) {
247 const U32 w = huffWeight[n];
248 CTable[n].nbBits = (BYTE)(tableLog + 1 - w);
249 }
250 }
251
252 /* fill val */
253 {
254 U16 nbPerRank[HUF_TABLELOG_MAX + 2] = {0}; /* support w=0=>n=tableLog+1 */
255 U16 valPerRank[HUF_TABLELOG_MAX + 2] = {0};
256 {
257 U32 n;
258 for (n = 0; n < nbSymbols; n++)
259 nbPerRank[CTable[n].nbBits]++;
260 }
261 /* determine stating value per rank */
262 valPerRank[tableLog + 1] = 0; /* for w==0 */
263 {
264 U16 min = 0;
265 U32 n;
266 for (n = tableLog; n > 0; n--) { /* start at n=tablelog <-> w=1 */
267 valPerRank[n] = min; /* get starting value within each rank */
268 min += nbPerRank[n];
269 min >>= 1;
270 }
271 }
272 /* assign value within rank, symbol order */
273 {
274 U32 n;
275 for (n = 0; n <= maxSymbolValue; n++)
276 CTable[n].val = valPerRank[CTable[n].nbBits]++;
277 }
278 }
279
280 return readSize;
281}
282
283typedef struct nodeElt_s {
284 U32 count;
285 U16 parent;
286 BYTE byte;
287 BYTE nbBits;
288} nodeElt;
289
290static U32 HUF_setMaxHeight(nodeElt *huffNode, U32 lastNonNull, U32 maxNbBits)
291{
292 const U32 largestBits = huffNode[lastNonNull].nbBits;
293 if (largestBits <= maxNbBits)
294 return largestBits; /* early exit : no elt > maxNbBits */
295
296 /* there are several too large elements (at least >= 2) */
297 {
298 int totalCost = 0;
299 const U32 baseCost = 1 << (largestBits - maxNbBits);
300 U32 n = lastNonNull;
301
302 while (huffNode[n].nbBits > maxNbBits) {
303 totalCost += baseCost - (1 << (largestBits - huffNode[n].nbBits));
304 huffNode[n].nbBits = (BYTE)maxNbBits;
305 n--;
306 } /* n stops at huffNode[n].nbBits <= maxNbBits */
307 while (huffNode[n].nbBits == maxNbBits)
308 n--; /* n end at index of smallest symbol using < maxNbBits */
309
310 /* renorm totalCost */
311 totalCost >>= (largestBits - maxNbBits); /* note : totalCost is necessarily a multiple of baseCost */
312
313 /* repay normalized cost */
314 {
315 U32 const noSymbol = 0xF0F0F0F0;
316 U32 rankLast[HUF_TABLELOG_MAX + 2];
317 int pos;
318
319 /* Get pos of last (smallest) symbol per rank */
320 memset(rankLast, 0xF0, sizeof(rankLast));
321 {
322 U32 currNbBits = maxNbBits;
323 for (pos = n; pos >= 0; pos--) {
324 if (huffNode[pos].nbBits >= currNbBits)
325 continue;
326 currNbBits = huffNode[pos].nbBits; /* < maxNbBits */
327 rankLast[maxNbBits - currNbBits] = pos;
328 }
329 }
330
331 while (totalCost > 0) {
332 U32 nBitsToDecrease = BIT_highbit32(totalCost) + 1;
333 for (; nBitsToDecrease > 1; nBitsToDecrease--) {
334 U32 highPos = rankLast[nBitsToDecrease];
335 U32 lowPos = rankLast[nBitsToDecrease - 1];
336 if (highPos == noSymbol)
337 continue;
338 if (lowPos == noSymbol)
339 break;
340 {
341 U32 const highTotal = huffNode[highPos].count;
342 U32 const lowTotal = 2 * huffNode[lowPos].count;
343 if (highTotal <= lowTotal)
344 break;
345 }
346 }
347 /* only triggered when no more rank 1 symbol left => find closest one (note : there is necessarily at least one !) */
348 /* HUF_MAX_TABLELOG test just to please gcc 5+; but it should not be necessary */
349 while ((nBitsToDecrease <= HUF_TABLELOG_MAX) && (rankLast[nBitsToDecrease] == noSymbol))
350 nBitsToDecrease++;
351 totalCost -= 1 << (nBitsToDecrease - 1);
352 if (rankLast[nBitsToDecrease - 1] == noSymbol)
353 rankLast[nBitsToDecrease - 1] = rankLast[nBitsToDecrease]; /* this rank is no longer empty */
354 huffNode[rankLast[nBitsToDecrease]].nbBits++;
355 if (rankLast[nBitsToDecrease] == 0) /* special case, reached largest symbol */
356 rankLast[nBitsToDecrease] = noSymbol;
357 else {
358 rankLast[nBitsToDecrease]--;
359 if (huffNode[rankLast[nBitsToDecrease]].nbBits != maxNbBits - nBitsToDecrease)
360 rankLast[nBitsToDecrease] = noSymbol; /* this rank is now empty */
361 }
362 } /* while (totalCost > 0) */
363
364 while (totalCost < 0) { /* Sometimes, cost correction overshoot */
365 if (rankLast[1] == noSymbol) { /* special case : no rank 1 symbol (using maxNbBits-1); let's create one from largest rank 0
366 (using maxNbBits) */
367 while (huffNode[n].nbBits == maxNbBits)
368 n--;
369 huffNode[n + 1].nbBits--;
370 rankLast[1] = n + 1;
371 totalCost++;
372 continue;
373 }
374 huffNode[rankLast[1] + 1].nbBits--;
375 rankLast[1]++;
376 totalCost++;
377 }
378 }
379 } /* there are several too large elements (at least >= 2) */
380
381 return maxNbBits;
382}
383
384typedef struct {
385 U32 base;
386 U32 curr;
387} rankPos;
388
389static void HUF_sort(nodeElt *huffNode, const U32 *count, U32 maxSymbolValue)
390{
391 rankPos rank[32];
392 U32 n;
393
394 memset(rank, 0, sizeof(rank));
395 for (n = 0; n <= maxSymbolValue; n++) {
396 U32 r = BIT_highbit32(count[n] + 1);
397 rank[r].base++;
398 }
399 for (n = 30; n > 0; n--)
400 rank[n - 1].base += rank[n].base;
401 for (n = 0; n < 32; n++)
402 rank[n].curr = rank[n].base;
403 for (n = 0; n <= maxSymbolValue; n++) {
404 U32 const c = count[n];
405 U32 const r = BIT_highbit32(c + 1) + 1;
406 U32 pos = rank[r].curr++;
407 while ((pos > rank[r].base) && (c > huffNode[pos - 1].count))
408 huffNode[pos] = huffNode[pos - 1], pos--;
409 huffNode[pos].count = c;
410 huffNode[pos].byte = (BYTE)n;
411 }
412}
413
414/** HUF_buildCTable_wksp() :
415 * Same as HUF_buildCTable(), but using externally allocated scratch buffer.
416 * `workSpace` must be aligned on 4-bytes boundaries, and be at least as large as a table of 1024 unsigned.
417 */
418#define STARTNODE (HUF_SYMBOLVALUE_MAX + 1)
419typedef nodeElt huffNodeTable[2 * HUF_SYMBOLVALUE_MAX + 1 + 1];
420size_t HUF_buildCTable_wksp(HUF_CElt *tree, const U32 *count, U32 maxSymbolValue, U32 maxNbBits, void *workSpace, size_t wkspSize)
421{
422 nodeElt *const huffNode0 = (nodeElt *)workSpace;
423 nodeElt *const huffNode = huffNode0 + 1;
424 U32 n, nonNullRank;
425 int lowS, lowN;
426 U16 nodeNb = STARTNODE;
427 U32 nodeRoot;
428
429 /* safety checks */
430 if (wkspSize < sizeof(huffNodeTable))
431 return ERROR(GENERIC); /* workSpace is not large enough */
432 if (maxNbBits == 0)
433 maxNbBits = HUF_TABLELOG_DEFAULT;
434 if (maxSymbolValue > HUF_SYMBOLVALUE_MAX)
435 return ERROR(GENERIC);
436 memset(huffNode0, 0, sizeof(huffNodeTable));
437
438 /* sort, decreasing order */
439 HUF_sort(huffNode, count, maxSymbolValue);
440
441 /* init for parents */
442 nonNullRank = maxSymbolValue;
443 while (huffNode[nonNullRank].count == 0)
444 nonNullRank--;
445 lowS = nonNullRank;
446 nodeRoot = nodeNb + lowS - 1;
447 lowN = nodeNb;
448 huffNode[nodeNb].count = huffNode[lowS].count + huffNode[lowS - 1].count;
449 huffNode[lowS].parent = huffNode[lowS - 1].parent = nodeNb;
450 nodeNb++;
451 lowS -= 2;
452 for (n = nodeNb; n <= nodeRoot; n++)
453 huffNode[n].count = (U32)(1U << 30);
454 huffNode0[0].count = (U32)(1U << 31); /* fake entry, strong barrier */
455
456 /* create parents */
457 while (nodeNb <= nodeRoot) {
458 U32 n1 = (huffNode[lowS].count < huffNode[lowN].count) ? lowS-- : lowN++;
459 U32 n2 = (huffNode[lowS].count < huffNode[lowN].count) ? lowS-- : lowN++;
460 huffNode[nodeNb].count = huffNode[n1].count + huffNode[n2].count;
461 huffNode[n1].parent = huffNode[n2].parent = nodeNb;
462 nodeNb++;
463 }
464
465 /* distribute weights (unlimited tree height) */
466 huffNode[nodeRoot].nbBits = 0;
467 for (n = nodeRoot - 1; n >= STARTNODE; n--)
468 huffNode[n].nbBits = huffNode[huffNode[n].parent].nbBits + 1;
469 for (n = 0; n <= nonNullRank; n++)
470 huffNode[n].nbBits = huffNode[huffNode[n].parent].nbBits + 1;
471
472 /* enforce maxTableLog */
473 maxNbBits = HUF_setMaxHeight(huffNode, nonNullRank, maxNbBits);
474
475 /* fill result into tree (val, nbBits) */
476 {
477 U16 nbPerRank[HUF_TABLELOG_MAX + 1] = {0};
478 U16 valPerRank[HUF_TABLELOG_MAX + 1] = {0};
479 if (maxNbBits > HUF_TABLELOG_MAX)
480 return ERROR(GENERIC); /* check fit into table */
481 for (n = 0; n <= nonNullRank; n++)
482 nbPerRank[huffNode[n].nbBits]++;
483 /* determine stating value per rank */
484 {
485 U16 min = 0;
486 for (n = maxNbBits; n > 0; n--) {
487 valPerRank[n] = min; /* get starting value within each rank */
488 min += nbPerRank[n];
489 min >>= 1;
490 }
491 }
492 for (n = 0; n <= maxSymbolValue; n++)
493 tree[huffNode[n].byte].nbBits = huffNode[n].nbBits; /* push nbBits per symbol, symbol order */
494 for (n = 0; n <= maxSymbolValue; n++)
495 tree[n].val = valPerRank[tree[n].nbBits]++; /* assign value within rank, symbol order */
496 }
497
498 return maxNbBits;
499}
500
501static size_t HUF_estimateCompressedSize(HUF_CElt *CTable, const unsigned *count, unsigned maxSymbolValue)
502{
503 size_t nbBits = 0;
504 int s;
505 for (s = 0; s <= (int)maxSymbolValue; ++s) {
506 nbBits += CTable[s].nbBits * count[s];
507 }
508 return nbBits >> 3;
509}
510
511static int HUF_validateCTable(const HUF_CElt *CTable, const unsigned *count, unsigned maxSymbolValue)
512{
513 int bad = 0;
514 int s;
515 for (s = 0; s <= (int)maxSymbolValue; ++s) {
516 bad |= (count[s] != 0) & (CTable[s].nbBits == 0);
517 }
518 return !bad;
519}
520
521static void HUF_encodeSymbol(BIT_CStream_t *bitCPtr, U32 symbol, const HUF_CElt *CTable)
522{
523 BIT_addBitsFast(bitCPtr, CTable[symbol].val, CTable[symbol].nbBits);
524}
525
526size_t HUF_compressBound(size_t size) { return HUF_COMPRESSBOUND(size); }
527
528#define HUF_FLUSHBITS(s) BIT_flushBits(s)
529
530#define HUF_FLUSHBITS_1(stream) \
531 if (sizeof((stream)->bitContainer) * 8 < HUF_TABLELOG_MAX * 2 + 7) \
532 HUF_FLUSHBITS(stream)
533
534#define HUF_FLUSHBITS_2(stream) \
535 if (sizeof((stream)->bitContainer) * 8 < HUF_TABLELOG_MAX * 4 + 7) \
536 HUF_FLUSHBITS(stream)
537
538size_t HUF_compress1X_usingCTable(void *dst, size_t dstSize, const void *src, size_t srcSize, const HUF_CElt *CTable)
539{
540 const BYTE *ip = (const BYTE *)src;
541 BYTE *const ostart = (BYTE *)dst;
542 BYTE *const oend = ostart + dstSize;
543 BYTE *op = ostart;
544 size_t n;
545 BIT_CStream_t bitC;
546
547 /* init */
548 if (dstSize < 8)
549 return 0; /* not enough space to compress */
550 {
551 size_t const initErr = BIT_initCStream(&bitC, op, oend - op);
552 if (HUF_isError(initErr))
553 return 0;
554 }
555
556 n = srcSize & ~3; /* join to mod 4 */
557 switch (srcSize & 3) {
558 case 3: HUF_encodeSymbol(&bitC, ip[n + 2], CTable); HUF_FLUSHBITS_2(&bitC);
559 fallthrough;
560 case 2: HUF_encodeSymbol(&bitC, ip[n + 1], CTable); HUF_FLUSHBITS_1(&bitC);
561 fallthrough;
562 case 1: HUF_encodeSymbol(&bitC, ip[n + 0], CTable); HUF_FLUSHBITS(&bitC);
563 fallthrough;
564 case 0:
565 default:;
566 }
567
568 for (; n > 0; n -= 4) { /* note : n&3==0 at this stage */
569 HUF_encodeSymbol(&bitC, ip[n - 1], CTable);
570 HUF_FLUSHBITS_1(&bitC);
571 HUF_encodeSymbol(&bitC, ip[n - 2], CTable);
572 HUF_FLUSHBITS_2(&bitC);
573 HUF_encodeSymbol(&bitC, ip[n - 3], CTable);
574 HUF_FLUSHBITS_1(&bitC);
575 HUF_encodeSymbol(&bitC, ip[n - 4], CTable);
576 HUF_FLUSHBITS(&bitC);
577 }
578
579 return BIT_closeCStream(&bitC);
580}
581
582size_t HUF_compress4X_usingCTable(void *dst, size_t dstSize, const void *src, size_t srcSize, const HUF_CElt *CTable)
583{
584 size_t const segmentSize = (srcSize + 3) / 4; /* first 3 segments */
585 const BYTE *ip = (const BYTE *)src;
586 const BYTE *const iend = ip + srcSize;
587 BYTE *const ostart = (BYTE *)dst;
588 BYTE *const oend = ostart + dstSize;
589 BYTE *op = ostart;
590
591 if (dstSize < 6 + 1 + 1 + 1 + 8)
592 return 0; /* minimum space to compress successfully */
593 if (srcSize < 12)
594 return 0; /* no saving possible : too small input */
595 op += 6; /* jumpTable */
596
597 {
598 CHECK_V_F(cSize, HUF_compress1X_usingCTable(op, oend - op, ip, segmentSize, CTable));
599 if (cSize == 0)
600 return 0;
601 ZSTD_writeLE16(ostart, (U16)cSize);
602 op += cSize;
603 }
604
605 ip += segmentSize;
606 {
607 CHECK_V_F(cSize, HUF_compress1X_usingCTable(op, oend - op, ip, segmentSize, CTable));
608 if (cSize == 0)
609 return 0;
610 ZSTD_writeLE16(ostart + 2, (U16)cSize);
611 op += cSize;
612 }
613
614 ip += segmentSize;
615 {
616 CHECK_V_F(cSize, HUF_compress1X_usingCTable(op, oend - op, ip, segmentSize, CTable));
617 if (cSize == 0)
618 return 0;
619 ZSTD_writeLE16(ostart + 4, (U16)cSize);
620 op += cSize;
621 }
622
623 ip += segmentSize;
624 {
625 CHECK_V_F(cSize, HUF_compress1X_usingCTable(op, oend - op, ip, iend - ip, CTable));
626 if (cSize == 0)
627 return 0;
628 op += cSize;
629 }
630
631 return op - ostart;
632}
633
634static size_t HUF_compressCTable_internal(BYTE *const ostart, BYTE *op, BYTE *const oend, const void *src, size_t srcSize, unsigned singleStream,
635 const HUF_CElt *CTable)
636{
637 size_t const cSize =
638 singleStream ? HUF_compress1X_usingCTable(op, oend - op, src, srcSize, CTable) : HUF_compress4X_usingCTable(op, oend - op, src, srcSize, CTable);
639 if (HUF_isError(cSize)) {
640 return cSize;
641 }
642 if (cSize == 0) {
643 return 0;
644 } /* uncompressible */
645 op += cSize;
646 /* check compressibility */
647 if ((size_t)(op - ostart) >= srcSize - 1) {
648 return 0;
649 }
650 return op - ostart;
651}
652
653/* `workSpace` must a table of at least 1024 unsigned */
654static size_t HUF_compress_internal(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog,
655 unsigned singleStream, void *workSpace, size_t wkspSize, HUF_CElt *oldHufTable, HUF_repeat *repeat, int preferRepeat)
656{
657 BYTE *const ostart = (BYTE *)dst;
658 BYTE *const oend = ostart + dstSize;
659 BYTE *op = ostart;
660
661 U32 *count;
662 size_t const countSize = sizeof(U32) * (HUF_SYMBOLVALUE_MAX + 1);
663 HUF_CElt *CTable;
664 size_t const CTableSize = sizeof(HUF_CElt) * (HUF_SYMBOLVALUE_MAX + 1);
665
666 /* checks & inits */
667 if (wkspSize < sizeof(huffNodeTable) + countSize + CTableSize)
668 return ERROR(GENERIC);
669 if (!srcSize)
670 return 0; /* Uncompressed (note : 1 means rle, so first byte must be correct) */
671 if (!dstSize)
672 return 0; /* cannot fit within dst budget */
673 if (srcSize > HUF_BLOCKSIZE_MAX)
674 return ERROR(srcSize_wrong); /* curr block size limit */
675 if (huffLog > HUF_TABLELOG_MAX)
676 return ERROR(tableLog_tooLarge);
677 if (!maxSymbolValue)
678 maxSymbolValue = HUF_SYMBOLVALUE_MAX;
679 if (!huffLog)
680 huffLog = HUF_TABLELOG_DEFAULT;
681
682 count = (U32 *)workSpace;
683 workSpace = (BYTE *)workSpace + countSize;
684 wkspSize -= countSize;
685 CTable = (HUF_CElt *)workSpace;
686 workSpace = (BYTE *)workSpace + CTableSize;
687 wkspSize -= CTableSize;
688
689 /* Heuristic : If we don't need to check the validity of the old table use the old table for small inputs */
690 if (preferRepeat && repeat && *repeat == HUF_repeat_valid) {
691 return HUF_compressCTable_internal(ostart, op, oend, src, srcSize, singleStream, oldHufTable);
692 }
693
694 /* Scan input and build symbol stats */
695 {
696 CHECK_V_F(largest, FSE_count_wksp(count, &maxSymbolValue, (const BYTE *)src, srcSize, (U32 *)workSpace));
697 if (largest == srcSize) {
698 *ostart = ((const BYTE *)src)[0];
699 return 1;
700 } /* single symbol, rle */
701 if (largest <= (srcSize >> 7) + 1)
702 return 0; /* Fast heuristic : not compressible enough */
703 }
704
705 /* Check validity of previous table */
706 if (repeat && *repeat == HUF_repeat_check && !HUF_validateCTable(oldHufTable, count, maxSymbolValue)) {
707 *repeat = HUF_repeat_none;
708 }
709 /* Heuristic : use existing table for small inputs */
710 if (preferRepeat && repeat && *repeat != HUF_repeat_none) {
711 return HUF_compressCTable_internal(ostart, op, oend, src, srcSize, singleStream, oldHufTable);
712 }
713
714 /* Build Huffman Tree */
715 huffLog = HUF_optimalTableLog(huffLog, srcSize, maxSymbolValue);
716 {
717 CHECK_V_F(maxBits, HUF_buildCTable_wksp(CTable, count, maxSymbolValue, huffLog, workSpace, wkspSize));
718 huffLog = (U32)maxBits;
719 /* Zero the unused symbols so we can check it for validity */
720 memset(CTable + maxSymbolValue + 1, 0, CTableSize - (maxSymbolValue + 1) * sizeof(HUF_CElt));
721 }
722
723 /* Write table description header */
724 {
725 CHECK_V_F(hSize, HUF_writeCTable_wksp(op, dstSize, CTable, maxSymbolValue, huffLog, workSpace, wkspSize));
726 /* Check if using the previous table will be beneficial */
727 if (repeat && *repeat != HUF_repeat_none) {
728 size_t const oldSize = HUF_estimateCompressedSize(oldHufTable, count, maxSymbolValue);
729 size_t const newSize = HUF_estimateCompressedSize(CTable, count, maxSymbolValue);
730 if (oldSize <= hSize + newSize || hSize + 12 >= srcSize) {
731 return HUF_compressCTable_internal(ostart, op, oend, src, srcSize, singleStream, oldHufTable);
732 }
733 }
734 /* Use the new table */
735 if (hSize + 12ul >= srcSize) {
736 return 0;
737 }
738 op += hSize;
739 if (repeat) {
740 *repeat = HUF_repeat_none;
741 }
742 if (oldHufTable) {
743 memcpy(oldHufTable, CTable, CTableSize);
744 } /* Save the new table */
745 }
746 return HUF_compressCTable_internal(ostart, op, oend, src, srcSize, singleStream, CTable);
747}
748
749size_t HUF_compress1X_wksp(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, void *workSpace,
750 size_t wkspSize)
751{
752 return HUF_compress_internal(dst, dstSize, src, srcSize, maxSymbolValue, huffLog, 1 /* single stream */, workSpace, wkspSize, NULL, NULL, 0);
753}
754
755size_t HUF_compress1X_repeat(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, void *workSpace,
756 size_t wkspSize, HUF_CElt *hufTable, HUF_repeat *repeat, int preferRepeat)
757{
758 return HUF_compress_internal(dst, dstSize, src, srcSize, maxSymbolValue, huffLog, 1 /* single stream */, workSpace, wkspSize, hufTable, repeat,
759 preferRepeat);
760}
761
762size_t HUF_compress4X_wksp(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, void *workSpace,
763 size_t wkspSize)
764{
765 return HUF_compress_internal(dst, dstSize, src, srcSize, maxSymbolValue, huffLog, 0 /* 4 streams */, workSpace, wkspSize, NULL, NULL, 0);
766}
767
768size_t HUF_compress4X_repeat(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, void *workSpace,
769 size_t wkspSize, HUF_CElt *hufTable, HUF_repeat *repeat, int preferRepeat)
770{
771 return HUF_compress_internal(dst, dstSize, src, srcSize, maxSymbolValue, huffLog, 0 /* 4 streams */, workSpace, wkspSize, hufTable, repeat,
772 preferRepeat);
773}