xref: /freebsd/sys/contrib/zstd/lib/decompress/huf_decompress.c (revision af23369a6deaaeb612ab266eb88b8bb8d560c322)
1 /* ******************************************************************
2  * huff0 huffman decoder,
3  * part of Finite State Entropy library
4  * Copyright (c) Yann Collet, Facebook, Inc.
5  *
6  *  You can contact the author at :
7  *  - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy
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 *  Dependencies
17 ****************************************************************/
18 #include "../common/zstd_deps.h"  /* ZSTD_memcpy, ZSTD_memset */
19 #include "../common/compiler.h"
20 #include "../common/bitstream.h"  /* BIT_* */
21 #include "../common/fse.h"        /* to compress headers */
22 #define HUF_STATIC_LINKING_ONLY
23 #include "../common/huf.h"
24 #include "../common/error_private.h"
25 #include "../common/zstd_internal.h"
26 
27 /* **************************************************************
28 *  Constants
29 ****************************************************************/
30 
31 #define HUF_DECODER_FAST_TABLELOG 11
32 
33 /* **************************************************************
34 *  Macros
35 ****************************************************************/
36 
37 /* These two optional macros force the use one way or another of the two
38  * Huffman decompression implementations. You can't force in both directions
39  * at the same time.
40  */
41 #if defined(HUF_FORCE_DECOMPRESS_X1) && \
42     defined(HUF_FORCE_DECOMPRESS_X2)
43 #error "Cannot force the use of the X1 and X2 decoders at the same time!"
44 #endif
45 
46 #if ZSTD_ENABLE_ASM_X86_64_BMI2 && DYNAMIC_BMI2
47 # define HUF_ASM_X86_64_BMI2_ATTRS BMI2_TARGET_ATTRIBUTE
48 #else
49 # define HUF_ASM_X86_64_BMI2_ATTRS
50 #endif
51 
52 #ifdef __cplusplus
53 # define HUF_EXTERN_C extern "C"
54 #else
55 # define HUF_EXTERN_C
56 #endif
57 #define HUF_ASM_DECL HUF_EXTERN_C
58 
59 #if DYNAMIC_BMI2 || (ZSTD_ENABLE_ASM_X86_64_BMI2 && defined(__BMI2__))
60 # define HUF_NEED_BMI2_FUNCTION 1
61 #else
62 # define HUF_NEED_BMI2_FUNCTION 0
63 #endif
64 
65 #if !(ZSTD_ENABLE_ASM_X86_64_BMI2 && defined(__BMI2__))
66 # define HUF_NEED_DEFAULT_FUNCTION 1
67 #else
68 # define HUF_NEED_DEFAULT_FUNCTION 0
69 #endif
70 
71 /* **************************************************************
72 *  Error Management
73 ****************************************************************/
74 #define HUF_isError ERR_isError
75 
76 
77 /* **************************************************************
78 *  Byte alignment for workSpace management
79 ****************************************************************/
80 #define HUF_ALIGN(x, a)         HUF_ALIGN_MASK((x), (a) - 1)
81 #define HUF_ALIGN_MASK(x, mask) (((x) + (mask)) & ~(mask))
82 
83 
84 /* **************************************************************
85 *  BMI2 Variant Wrappers
86 ****************************************************************/
87 #if DYNAMIC_BMI2
88 
89 #define HUF_DGEN(fn)                                                        \
90                                                                             \
91     static size_t fn##_default(                                             \
92                   void* dst,  size_t dstSize,                               \
93             const void* cSrc, size_t cSrcSize,                              \
94             const HUF_DTable* DTable)                                       \
95     {                                                                       \
96         return fn##_body(dst, dstSize, cSrc, cSrcSize, DTable);             \
97     }                                                                       \
98                                                                             \
99     static BMI2_TARGET_ATTRIBUTE size_t fn##_bmi2(                          \
100                   void* dst,  size_t dstSize,                               \
101             const void* cSrc, size_t cSrcSize,                              \
102             const HUF_DTable* DTable)                                       \
103     {                                                                       \
104         return fn##_body(dst, dstSize, cSrc, cSrcSize, DTable);             \
105     }                                                                       \
106                                                                             \
107     static size_t fn(void* dst, size_t dstSize, void const* cSrc,           \
108                      size_t cSrcSize, HUF_DTable const* DTable, int bmi2)   \
109     {                                                                       \
110         if (bmi2) {                                                         \
111             return fn##_bmi2(dst, dstSize, cSrc, cSrcSize, DTable);         \
112         }                                                                   \
113         return fn##_default(dst, dstSize, cSrc, cSrcSize, DTable);          \
114     }
115 
116 #else
117 
118 #define HUF_DGEN(fn)                                                        \
119     static size_t fn(void* dst, size_t dstSize, void const* cSrc,           \
120                      size_t cSrcSize, HUF_DTable const* DTable, int bmi2)   \
121     {                                                                       \
122         (void)bmi2;                                                         \
123         return fn##_body(dst, dstSize, cSrc, cSrcSize, DTable);             \
124     }
125 
126 #endif
127 
128 
129 /*-***************************/
130 /*  generic DTableDesc       */
131 /*-***************************/
132 typedef struct { BYTE maxTableLog; BYTE tableType; BYTE tableLog; BYTE reserved; } DTableDesc;
133 
134 static DTableDesc HUF_getDTableDesc(const HUF_DTable* table)
135 {
136     DTableDesc dtd;
137     ZSTD_memcpy(&dtd, table, sizeof(dtd));
138     return dtd;
139 }
140 
141 #if ZSTD_ENABLE_ASM_X86_64_BMI2
142 
143 static size_t HUF_initDStream(BYTE const* ip) {
144     BYTE const lastByte = ip[7];
145     size_t const bitsConsumed = lastByte ? 8 - BIT_highbit32(lastByte) : 0;
146     size_t const value = MEM_readLEST(ip) | 1;
147     assert(bitsConsumed <= 8);
148     return value << bitsConsumed;
149 }
150 typedef struct {
151     BYTE const* ip[4];
152     BYTE* op[4];
153     U64 bits[4];
154     void const* dt;
155     BYTE const* ilimit;
156     BYTE* oend;
157     BYTE const* iend[4];
158 } HUF_DecompressAsmArgs;
159 
160 /**
161  * Initializes args for the asm decoding loop.
162  * @returns 0 on success
163  *          1 if the fallback implementation should be used.
164  *          Or an error code on failure.
165  */
166 static size_t HUF_DecompressAsmArgs_init(HUF_DecompressAsmArgs* args, void* dst, size_t dstSize, void const* src, size_t srcSize, const HUF_DTable* DTable)
167 {
168     void const* dt = DTable + 1;
169     U32 const dtLog = HUF_getDTableDesc(DTable).tableLog;
170 
171     const BYTE* const ilimit = (const BYTE*)src + 6 + 8;
172 
173     BYTE* const oend = (BYTE*)dst + dstSize;
174 
175     /* The following condition is false on x32 platform,
176      * but HUF_asm is not compatible with this ABI */
177     if (!(MEM_isLittleEndian() && !MEM_32bits())) return 1;
178 
179     /* strict minimum : jump table + 1 byte per stream */
180     if (srcSize < 10)
181         return ERROR(corruption_detected);
182 
183     /* Must have at least 8 bytes per stream because we don't handle initializing smaller bit containers.
184      * If table log is not correct at this point, fallback to the old decoder.
185      * On small inputs we don't have enough data to trigger the fast loop, so use the old decoder.
186      */
187     if (dtLog != HUF_DECODER_FAST_TABLELOG)
188         return 1;
189 
190     /* Read the jump table. */
191     {
192         const BYTE* const istart = (const BYTE*)src;
193         size_t const length1 = MEM_readLE16(istart);
194         size_t const length2 = MEM_readLE16(istart+2);
195         size_t const length3 = MEM_readLE16(istart+4);
196         size_t const length4 = srcSize - (length1 + length2 + length3 + 6);
197         args->iend[0] = istart + 6;  /* jumpTable */
198         args->iend[1] = args->iend[0] + length1;
199         args->iend[2] = args->iend[1] + length2;
200         args->iend[3] = args->iend[2] + length3;
201 
202         /* HUF_initDStream() requires this, and this small of an input
203          * won't benefit from the ASM loop anyways.
204          * length1 must be >= 16 so that ip[0] >= ilimit before the loop
205          * starts.
206          */
207         if (length1 < 16 || length2 < 8 || length3 < 8 || length4 < 8)
208             return 1;
209         if (length4 > srcSize) return ERROR(corruption_detected);   /* overflow */
210     }
211     /* ip[] contains the position that is currently loaded into bits[]. */
212     args->ip[0] = args->iend[1] - sizeof(U64);
213     args->ip[1] = args->iend[2] - sizeof(U64);
214     args->ip[2] = args->iend[3] - sizeof(U64);
215     args->ip[3] = (BYTE const*)src + srcSize - sizeof(U64);
216 
217     /* op[] contains the output pointers. */
218     args->op[0] = (BYTE*)dst;
219     args->op[1] = args->op[0] + (dstSize+3)/4;
220     args->op[2] = args->op[1] + (dstSize+3)/4;
221     args->op[3] = args->op[2] + (dstSize+3)/4;
222 
223     /* No point to call the ASM loop for tiny outputs. */
224     if (args->op[3] >= oend)
225         return 1;
226 
227     /* bits[] is the bit container.
228         * It is read from the MSB down to the LSB.
229         * It is shifted left as it is read, and zeros are
230         * shifted in. After the lowest valid bit a 1 is
231         * set, so that CountTrailingZeros(bits[]) can be used
232         * to count how many bits we've consumed.
233         */
234     args->bits[0] = HUF_initDStream(args->ip[0]);
235     args->bits[1] = HUF_initDStream(args->ip[1]);
236     args->bits[2] = HUF_initDStream(args->ip[2]);
237     args->bits[3] = HUF_initDStream(args->ip[3]);
238 
239     /* If ip[] >= ilimit, it is guaranteed to be safe to
240         * reload bits[]. It may be beyond its section, but is
241         * guaranteed to be valid (>= istart).
242         */
243     args->ilimit = ilimit;
244 
245     args->oend = oend;
246     args->dt = dt;
247 
248     return 0;
249 }
250 
251 static size_t HUF_initRemainingDStream(BIT_DStream_t* bit, HUF_DecompressAsmArgs const* args, int stream, BYTE* segmentEnd)
252 {
253     /* Validate that we haven't overwritten. */
254     if (args->op[stream] > segmentEnd)
255         return ERROR(corruption_detected);
256     /* Validate that we haven't read beyond iend[].
257         * Note that ip[] may be < iend[] because the MSB is
258         * the next bit to read, and we may have consumed 100%
259         * of the stream, so down to iend[i] - 8 is valid.
260         */
261     if (args->ip[stream] < args->iend[stream] - 8)
262         return ERROR(corruption_detected);
263 
264     /* Construct the BIT_DStream_t. */
265     bit->bitContainer = MEM_readLE64(args->ip[stream]);
266     bit->bitsConsumed = ZSTD_countTrailingZeros((size_t)args->bits[stream]);
267     bit->start = (const char*)args->iend[0];
268     bit->limitPtr = bit->start + sizeof(size_t);
269     bit->ptr = (const char*)args->ip[stream];
270 
271     return 0;
272 }
273 #endif
274 
275 
276 #ifndef HUF_FORCE_DECOMPRESS_X2
277 
278 /*-***************************/
279 /*  single-symbol decoding   */
280 /*-***************************/
281 typedef struct { BYTE nbBits; BYTE byte; } HUF_DEltX1;   /* single-symbol decoding */
282 
283 /**
284  * Packs 4 HUF_DEltX1 structs into a U64. This is used to lay down 4 entries at
285  * a time.
286  */
287 static U64 HUF_DEltX1_set4(BYTE symbol, BYTE nbBits) {
288     U64 D4;
289     if (MEM_isLittleEndian()) {
290         D4 = (symbol << 8) + nbBits;
291     } else {
292         D4 = symbol + (nbBits << 8);
293     }
294     D4 *= 0x0001000100010001ULL;
295     return D4;
296 }
297 
298 /**
299  * Increase the tableLog to targetTableLog and rescales the stats.
300  * If tableLog > targetTableLog this is a no-op.
301  * @returns New tableLog
302  */
303 static U32 HUF_rescaleStats(BYTE* huffWeight, U32* rankVal, U32 nbSymbols, U32 tableLog, U32 targetTableLog)
304 {
305     if (tableLog > targetTableLog)
306         return tableLog;
307     if (tableLog < targetTableLog) {
308         U32 const scale = targetTableLog - tableLog;
309         U32 s;
310         /* Increase the weight for all non-zero probability symbols by scale. */
311         for (s = 0; s < nbSymbols; ++s) {
312             huffWeight[s] += (BYTE)((huffWeight[s] == 0) ? 0 : scale);
313         }
314         /* Update rankVal to reflect the new weights.
315          * All weights except 0 get moved to weight + scale.
316          * Weights [1, scale] are empty.
317          */
318         for (s = targetTableLog; s > scale; --s) {
319             rankVal[s] = rankVal[s - scale];
320         }
321         for (s = scale; s > 0; --s) {
322             rankVal[s] = 0;
323         }
324     }
325     return targetTableLog;
326 }
327 
328 typedef struct {
329         U32 rankVal[HUF_TABLELOG_ABSOLUTEMAX + 1];
330         U32 rankStart[HUF_TABLELOG_ABSOLUTEMAX + 1];
331         U32 statsWksp[HUF_READ_STATS_WORKSPACE_SIZE_U32];
332         BYTE symbols[HUF_SYMBOLVALUE_MAX + 1];
333         BYTE huffWeight[HUF_SYMBOLVALUE_MAX + 1];
334 } HUF_ReadDTableX1_Workspace;
335 
336 
337 size_t HUF_readDTableX1_wksp(HUF_DTable* DTable, const void* src, size_t srcSize, void* workSpace, size_t wkspSize)
338 {
339     return HUF_readDTableX1_wksp_bmi2(DTable, src, srcSize, workSpace, wkspSize, /* bmi2 */ 0);
340 }
341 
342 size_t HUF_readDTableX1_wksp_bmi2(HUF_DTable* DTable, const void* src, size_t srcSize, void* workSpace, size_t wkspSize, int bmi2)
343 {
344     U32 tableLog = 0;
345     U32 nbSymbols = 0;
346     size_t iSize;
347     void* const dtPtr = DTable + 1;
348     HUF_DEltX1* const dt = (HUF_DEltX1*)dtPtr;
349     HUF_ReadDTableX1_Workspace* wksp = (HUF_ReadDTableX1_Workspace*)workSpace;
350 
351     DEBUG_STATIC_ASSERT(HUF_DECOMPRESS_WORKSPACE_SIZE >= sizeof(*wksp));
352     if (sizeof(*wksp) > wkspSize) return ERROR(tableLog_tooLarge);
353 
354     DEBUG_STATIC_ASSERT(sizeof(DTableDesc) == sizeof(HUF_DTable));
355     /* ZSTD_memset(huffWeight, 0, sizeof(huffWeight)); */   /* is not necessary, even though some analyzer complain ... */
356 
357     iSize = HUF_readStats_wksp(wksp->huffWeight, HUF_SYMBOLVALUE_MAX + 1, wksp->rankVal, &nbSymbols, &tableLog, src, srcSize, wksp->statsWksp, sizeof(wksp->statsWksp), bmi2);
358     if (HUF_isError(iSize)) return iSize;
359 
360 
361     /* Table header */
362     {   DTableDesc dtd = HUF_getDTableDesc(DTable);
363         U32 const maxTableLog = dtd.maxTableLog + 1;
364         U32 const targetTableLog = MIN(maxTableLog, HUF_DECODER_FAST_TABLELOG);
365         tableLog = HUF_rescaleStats(wksp->huffWeight, wksp->rankVal, nbSymbols, tableLog, targetTableLog);
366         if (tableLog > (U32)(dtd.maxTableLog+1)) return ERROR(tableLog_tooLarge);   /* DTable too small, Huffman tree cannot fit in */
367         dtd.tableType = 0;
368         dtd.tableLog = (BYTE)tableLog;
369         ZSTD_memcpy(DTable, &dtd, sizeof(dtd));
370     }
371 
372     /* Compute symbols and rankStart given rankVal:
373      *
374      * rankVal already contains the number of values of each weight.
375      *
376      * symbols contains the symbols ordered by weight. First are the rankVal[0]
377      * weight 0 symbols, followed by the rankVal[1] weight 1 symbols, and so on.
378      * symbols[0] is filled (but unused) to avoid a branch.
379      *
380      * rankStart contains the offset where each rank belongs in the DTable.
381      * rankStart[0] is not filled because there are no entries in the table for
382      * weight 0.
383      */
384     {
385         int n;
386         int nextRankStart = 0;
387         int const unroll = 4;
388         int const nLimit = (int)nbSymbols - unroll + 1;
389         for (n=0; n<(int)tableLog+1; n++) {
390             U32 const curr = nextRankStart;
391             nextRankStart += wksp->rankVal[n];
392             wksp->rankStart[n] = curr;
393         }
394         for (n=0; n < nLimit; n += unroll) {
395             int u;
396             for (u=0; u < unroll; ++u) {
397                 size_t const w = wksp->huffWeight[n+u];
398                 wksp->symbols[wksp->rankStart[w]++] = (BYTE)(n+u);
399             }
400         }
401         for (; n < (int)nbSymbols; ++n) {
402             size_t const w = wksp->huffWeight[n];
403             wksp->symbols[wksp->rankStart[w]++] = (BYTE)n;
404         }
405     }
406 
407     /* fill DTable
408      * We fill all entries of each weight in order.
409      * That way length is a constant for each iteration of the outer loop.
410      * We can switch based on the length to a different inner loop which is
411      * optimized for that particular case.
412      */
413     {
414         U32 w;
415         int symbol=wksp->rankVal[0];
416         int rankStart=0;
417         for (w=1; w<tableLog+1; ++w) {
418             int const symbolCount = wksp->rankVal[w];
419             int const length = (1 << w) >> 1;
420             int uStart = rankStart;
421             BYTE const nbBits = (BYTE)(tableLog + 1 - w);
422             int s;
423             int u;
424             switch (length) {
425             case 1:
426                 for (s=0; s<symbolCount; ++s) {
427                     HUF_DEltX1 D;
428                     D.byte = wksp->symbols[symbol + s];
429                     D.nbBits = nbBits;
430                     dt[uStart] = D;
431                     uStart += 1;
432                 }
433                 break;
434             case 2:
435                 for (s=0; s<symbolCount; ++s) {
436                     HUF_DEltX1 D;
437                     D.byte = wksp->symbols[symbol + s];
438                     D.nbBits = nbBits;
439                     dt[uStart+0] = D;
440                     dt[uStart+1] = D;
441                     uStart += 2;
442                 }
443                 break;
444             case 4:
445                 for (s=0; s<symbolCount; ++s) {
446                     U64 const D4 = HUF_DEltX1_set4(wksp->symbols[symbol + s], nbBits);
447                     MEM_write64(dt + uStart, D4);
448                     uStart += 4;
449                 }
450                 break;
451             case 8:
452                 for (s=0; s<symbolCount; ++s) {
453                     U64 const D4 = HUF_DEltX1_set4(wksp->symbols[symbol + s], nbBits);
454                     MEM_write64(dt + uStart, D4);
455                     MEM_write64(dt + uStart + 4, D4);
456                     uStart += 8;
457                 }
458                 break;
459             default:
460                 for (s=0; s<symbolCount; ++s) {
461                     U64 const D4 = HUF_DEltX1_set4(wksp->symbols[symbol + s], nbBits);
462                     for (u=0; u < length; u += 16) {
463                         MEM_write64(dt + uStart + u + 0, D4);
464                         MEM_write64(dt + uStart + u + 4, D4);
465                         MEM_write64(dt + uStart + u + 8, D4);
466                         MEM_write64(dt + uStart + u + 12, D4);
467                     }
468                     assert(u == length);
469                     uStart += length;
470                 }
471                 break;
472             }
473             symbol += symbolCount;
474             rankStart += symbolCount * length;
475         }
476     }
477     return iSize;
478 }
479 
480 FORCE_INLINE_TEMPLATE BYTE
481 HUF_decodeSymbolX1(BIT_DStream_t* Dstream, const HUF_DEltX1* dt, const U32 dtLog)
482 {
483     size_t const val = BIT_lookBitsFast(Dstream, dtLog); /* note : dtLog >= 1 */
484     BYTE const c = dt[val].byte;
485     BIT_skipBits(Dstream, dt[val].nbBits);
486     return c;
487 }
488 
489 #define HUF_DECODE_SYMBOLX1_0(ptr, DStreamPtr) \
490     *ptr++ = HUF_decodeSymbolX1(DStreamPtr, dt, dtLog)
491 
492 #define HUF_DECODE_SYMBOLX1_1(ptr, DStreamPtr)  \
493     if (MEM_64bits() || (HUF_TABLELOG_MAX<=12)) \
494         HUF_DECODE_SYMBOLX1_0(ptr, DStreamPtr)
495 
496 #define HUF_DECODE_SYMBOLX1_2(ptr, DStreamPtr) \
497     if (MEM_64bits()) \
498         HUF_DECODE_SYMBOLX1_0(ptr, DStreamPtr)
499 
500 HINT_INLINE size_t
501 HUF_decodeStreamX1(BYTE* p, BIT_DStream_t* const bitDPtr, BYTE* const pEnd, const HUF_DEltX1* const dt, const U32 dtLog)
502 {
503     BYTE* const pStart = p;
504 
505     /* up to 4 symbols at a time */
506     if ((pEnd - p) > 3) {
507         while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) & (p < pEnd-3)) {
508             HUF_DECODE_SYMBOLX1_2(p, bitDPtr);
509             HUF_DECODE_SYMBOLX1_1(p, bitDPtr);
510             HUF_DECODE_SYMBOLX1_2(p, bitDPtr);
511             HUF_DECODE_SYMBOLX1_0(p, bitDPtr);
512         }
513     } else {
514         BIT_reloadDStream(bitDPtr);
515     }
516 
517     /* [0-3] symbols remaining */
518     if (MEM_32bits())
519         while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) & (p < pEnd))
520             HUF_DECODE_SYMBOLX1_0(p, bitDPtr);
521 
522     /* no more data to retrieve from bitstream, no need to reload */
523     while (p < pEnd)
524         HUF_DECODE_SYMBOLX1_0(p, bitDPtr);
525 
526     return pEnd-pStart;
527 }
528 
529 FORCE_INLINE_TEMPLATE size_t
530 HUF_decompress1X1_usingDTable_internal_body(
531           void* dst,  size_t dstSize,
532     const void* cSrc, size_t cSrcSize,
533     const HUF_DTable* DTable)
534 {
535     BYTE* op = (BYTE*)dst;
536     BYTE* const oend = op + dstSize;
537     const void* dtPtr = DTable + 1;
538     const HUF_DEltX1* const dt = (const HUF_DEltX1*)dtPtr;
539     BIT_DStream_t bitD;
540     DTableDesc const dtd = HUF_getDTableDesc(DTable);
541     U32 const dtLog = dtd.tableLog;
542 
543     CHECK_F( BIT_initDStream(&bitD, cSrc, cSrcSize) );
544 
545     HUF_decodeStreamX1(op, &bitD, oend, dt, dtLog);
546 
547     if (!BIT_endOfDStream(&bitD)) return ERROR(corruption_detected);
548 
549     return dstSize;
550 }
551 
552 FORCE_INLINE_TEMPLATE size_t
553 HUF_decompress4X1_usingDTable_internal_body(
554           void* dst,  size_t dstSize,
555     const void* cSrc, size_t cSrcSize,
556     const HUF_DTable* DTable)
557 {
558     /* Check */
559     if (cSrcSize < 10) return ERROR(corruption_detected);  /* strict minimum : jump table + 1 byte per stream */
560 
561     {   const BYTE* const istart = (const BYTE*) cSrc;
562         BYTE* const ostart = (BYTE*) dst;
563         BYTE* const oend = ostart + dstSize;
564         BYTE* const olimit = oend - 3;
565         const void* const dtPtr = DTable + 1;
566         const HUF_DEltX1* const dt = (const HUF_DEltX1*)dtPtr;
567 
568         /* Init */
569         BIT_DStream_t bitD1;
570         BIT_DStream_t bitD2;
571         BIT_DStream_t bitD3;
572         BIT_DStream_t bitD4;
573         size_t const length1 = MEM_readLE16(istart);
574         size_t const length2 = MEM_readLE16(istart+2);
575         size_t const length3 = MEM_readLE16(istart+4);
576         size_t const length4 = cSrcSize - (length1 + length2 + length3 + 6);
577         const BYTE* const istart1 = istart + 6;  /* jumpTable */
578         const BYTE* const istart2 = istart1 + length1;
579         const BYTE* const istart3 = istart2 + length2;
580         const BYTE* const istart4 = istart3 + length3;
581         const size_t segmentSize = (dstSize+3) / 4;
582         BYTE* const opStart2 = ostart + segmentSize;
583         BYTE* const opStart3 = opStart2 + segmentSize;
584         BYTE* const opStart4 = opStart3 + segmentSize;
585         BYTE* op1 = ostart;
586         BYTE* op2 = opStart2;
587         BYTE* op3 = opStart3;
588         BYTE* op4 = opStart4;
589         DTableDesc const dtd = HUF_getDTableDesc(DTable);
590         U32 const dtLog = dtd.tableLog;
591         U32 endSignal = 1;
592 
593         if (length4 > cSrcSize) return ERROR(corruption_detected);   /* overflow */
594         if (opStart4 > oend) return ERROR(corruption_detected);      /* overflow */
595         CHECK_F( BIT_initDStream(&bitD1, istart1, length1) );
596         CHECK_F( BIT_initDStream(&bitD2, istart2, length2) );
597         CHECK_F( BIT_initDStream(&bitD3, istart3, length3) );
598         CHECK_F( BIT_initDStream(&bitD4, istart4, length4) );
599 
600         /* up to 16 symbols per loop (4 symbols per stream) in 64-bit mode */
601         if ((size_t)(oend - op4) >= sizeof(size_t)) {
602             for ( ; (endSignal) & (op4 < olimit) ; ) {
603                 HUF_DECODE_SYMBOLX1_2(op1, &bitD1);
604                 HUF_DECODE_SYMBOLX1_2(op2, &bitD2);
605                 HUF_DECODE_SYMBOLX1_2(op3, &bitD3);
606                 HUF_DECODE_SYMBOLX1_2(op4, &bitD4);
607                 HUF_DECODE_SYMBOLX1_1(op1, &bitD1);
608                 HUF_DECODE_SYMBOLX1_1(op2, &bitD2);
609                 HUF_DECODE_SYMBOLX1_1(op3, &bitD3);
610                 HUF_DECODE_SYMBOLX1_1(op4, &bitD4);
611                 HUF_DECODE_SYMBOLX1_2(op1, &bitD1);
612                 HUF_DECODE_SYMBOLX1_2(op2, &bitD2);
613                 HUF_DECODE_SYMBOLX1_2(op3, &bitD3);
614                 HUF_DECODE_SYMBOLX1_2(op4, &bitD4);
615                 HUF_DECODE_SYMBOLX1_0(op1, &bitD1);
616                 HUF_DECODE_SYMBOLX1_0(op2, &bitD2);
617                 HUF_DECODE_SYMBOLX1_0(op3, &bitD3);
618                 HUF_DECODE_SYMBOLX1_0(op4, &bitD4);
619                 endSignal &= BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished;
620                 endSignal &= BIT_reloadDStreamFast(&bitD2) == BIT_DStream_unfinished;
621                 endSignal &= BIT_reloadDStreamFast(&bitD3) == BIT_DStream_unfinished;
622                 endSignal &= BIT_reloadDStreamFast(&bitD4) == BIT_DStream_unfinished;
623             }
624         }
625 
626         /* check corruption */
627         /* note : should not be necessary : op# advance in lock step, and we control op4.
628          *        but curiously, binary generated by gcc 7.2 & 7.3 with -mbmi2 runs faster when >=1 test is present */
629         if (op1 > opStart2) return ERROR(corruption_detected);
630         if (op2 > opStart3) return ERROR(corruption_detected);
631         if (op3 > opStart4) return ERROR(corruption_detected);
632         /* note : op4 supposed already verified within main loop */
633 
634         /* finish bitStreams one by one */
635         HUF_decodeStreamX1(op1, &bitD1, opStart2, dt, dtLog);
636         HUF_decodeStreamX1(op2, &bitD2, opStart3, dt, dtLog);
637         HUF_decodeStreamX1(op3, &bitD3, opStart4, dt, dtLog);
638         HUF_decodeStreamX1(op4, &bitD4, oend,     dt, dtLog);
639 
640         /* check */
641         { U32 const endCheck = BIT_endOfDStream(&bitD1) & BIT_endOfDStream(&bitD2) & BIT_endOfDStream(&bitD3) & BIT_endOfDStream(&bitD4);
642           if (!endCheck) return ERROR(corruption_detected); }
643 
644         /* decoded size */
645         return dstSize;
646     }
647 }
648 
649 #if HUF_NEED_BMI2_FUNCTION
650 static BMI2_TARGET_ATTRIBUTE
651 size_t HUF_decompress4X1_usingDTable_internal_bmi2(void* dst, size_t dstSize, void const* cSrc,
652                     size_t cSrcSize, HUF_DTable const* DTable) {
653     return HUF_decompress4X1_usingDTable_internal_body(dst, dstSize, cSrc, cSrcSize, DTable);
654 }
655 #endif
656 
657 #if HUF_NEED_DEFAULT_FUNCTION
658 static
659 size_t HUF_decompress4X1_usingDTable_internal_default(void* dst, size_t dstSize, void const* cSrc,
660                     size_t cSrcSize, HUF_DTable const* DTable) {
661     return HUF_decompress4X1_usingDTable_internal_body(dst, dstSize, cSrc, cSrcSize, DTable);
662 }
663 #endif
664 
665 #if ZSTD_ENABLE_ASM_X86_64_BMI2
666 
667 HUF_ASM_DECL void HUF_decompress4X1_usingDTable_internal_bmi2_asm_loop(HUF_DecompressAsmArgs* args) ZSTDLIB_HIDDEN;
668 
669 static HUF_ASM_X86_64_BMI2_ATTRS
670 size_t
671 HUF_decompress4X1_usingDTable_internal_bmi2_asm(
672           void* dst,  size_t dstSize,
673     const void* cSrc, size_t cSrcSize,
674     const HUF_DTable* DTable)
675 {
676     void const* dt = DTable + 1;
677     const BYTE* const iend = (const BYTE*)cSrc + 6;
678     BYTE* const oend = (BYTE*)dst + dstSize;
679     HUF_DecompressAsmArgs args;
680     {
681         size_t const ret = HUF_DecompressAsmArgs_init(&args, dst, dstSize, cSrc, cSrcSize, DTable);
682         FORWARD_IF_ERROR(ret, "Failed to init asm args");
683         if (ret != 0)
684             return HUF_decompress4X1_usingDTable_internal_bmi2(dst, dstSize, cSrc, cSrcSize, DTable);
685     }
686 
687     assert(args.ip[0] >= args.ilimit);
688     HUF_decompress4X1_usingDTable_internal_bmi2_asm_loop(&args);
689 
690     /* Our loop guarantees that ip[] >= ilimit and that we haven't
691     * overwritten any op[].
692     */
693     assert(args.ip[0] >= iend);
694     assert(args.ip[1] >= iend);
695     assert(args.ip[2] >= iend);
696     assert(args.ip[3] >= iend);
697     assert(args.op[3] <= oend);
698     (void)iend;
699 
700     /* finish bit streams one by one. */
701     {
702         size_t const segmentSize = (dstSize+3) / 4;
703         BYTE* segmentEnd = (BYTE*)dst;
704         int i;
705         for (i = 0; i < 4; ++i) {
706             BIT_DStream_t bit;
707             if (segmentSize <= (size_t)(oend - segmentEnd))
708                 segmentEnd += segmentSize;
709             else
710                 segmentEnd = oend;
711             FORWARD_IF_ERROR(HUF_initRemainingDStream(&bit, &args, i, segmentEnd), "corruption");
712             /* Decompress and validate that we've produced exactly the expected length. */
713             args.op[i] += HUF_decodeStreamX1(args.op[i], &bit, segmentEnd, (HUF_DEltX1 const*)dt, HUF_DECODER_FAST_TABLELOG);
714             if (args.op[i] != segmentEnd) return ERROR(corruption_detected);
715         }
716     }
717 
718     /* decoded size */
719     return dstSize;
720 }
721 #endif /* ZSTD_ENABLE_ASM_X86_64_BMI2 */
722 
723 typedef size_t (*HUF_decompress_usingDTable_t)(void *dst, size_t dstSize,
724                                                const void *cSrc,
725                                                size_t cSrcSize,
726                                                const HUF_DTable *DTable);
727 
728 HUF_DGEN(HUF_decompress1X1_usingDTable_internal)
729 
730 static size_t HUF_decompress4X1_usingDTable_internal(void* dst, size_t dstSize, void const* cSrc,
731                     size_t cSrcSize, HUF_DTable const* DTable, int bmi2)
732 {
733 #if DYNAMIC_BMI2
734     if (bmi2) {
735 # if ZSTD_ENABLE_ASM_X86_64_BMI2
736         return HUF_decompress4X1_usingDTable_internal_bmi2_asm(dst, dstSize, cSrc, cSrcSize, DTable);
737 # else
738         return HUF_decompress4X1_usingDTable_internal_bmi2(dst, dstSize, cSrc, cSrcSize, DTable);
739 # endif
740     }
741 #else
742     (void)bmi2;
743 #endif
744 
745 #if ZSTD_ENABLE_ASM_X86_64_BMI2 && defined(__BMI2__)
746     return HUF_decompress4X1_usingDTable_internal_bmi2_asm(dst, dstSize, cSrc, cSrcSize, DTable);
747 #else
748     return HUF_decompress4X1_usingDTable_internal_default(dst, dstSize, cSrc, cSrcSize, DTable);
749 #endif
750 }
751 
752 
753 size_t HUF_decompress1X1_usingDTable(
754           void* dst,  size_t dstSize,
755     const void* cSrc, size_t cSrcSize,
756     const HUF_DTable* DTable)
757 {
758     DTableDesc dtd = HUF_getDTableDesc(DTable);
759     if (dtd.tableType != 0) return ERROR(GENERIC);
760     return HUF_decompress1X1_usingDTable_internal(dst, dstSize, cSrc, cSrcSize, DTable, /* bmi2 */ 0);
761 }
762 
763 size_t HUF_decompress1X1_DCtx_wksp(HUF_DTable* DCtx, void* dst, size_t dstSize,
764                                    const void* cSrc, size_t cSrcSize,
765                                    void* workSpace, size_t wkspSize)
766 {
767     const BYTE* ip = (const BYTE*) cSrc;
768 
769     size_t const hSize = HUF_readDTableX1_wksp(DCtx, cSrc, cSrcSize, workSpace, wkspSize);
770     if (HUF_isError(hSize)) return hSize;
771     if (hSize >= cSrcSize) return ERROR(srcSize_wrong);
772     ip += hSize; cSrcSize -= hSize;
773 
774     return HUF_decompress1X1_usingDTable_internal(dst, dstSize, ip, cSrcSize, DCtx, /* bmi2 */ 0);
775 }
776 
777 
778 size_t HUF_decompress4X1_usingDTable(
779           void* dst,  size_t dstSize,
780     const void* cSrc, size_t cSrcSize,
781     const HUF_DTable* DTable)
782 {
783     DTableDesc dtd = HUF_getDTableDesc(DTable);
784     if (dtd.tableType != 0) return ERROR(GENERIC);
785     return HUF_decompress4X1_usingDTable_internal(dst, dstSize, cSrc, cSrcSize, DTable, /* bmi2 */ 0);
786 }
787 
788 static size_t HUF_decompress4X1_DCtx_wksp_bmi2(HUF_DTable* dctx, void* dst, size_t dstSize,
789                                    const void* cSrc, size_t cSrcSize,
790                                    void* workSpace, size_t wkspSize, int bmi2)
791 {
792     const BYTE* ip = (const BYTE*) cSrc;
793 
794     size_t const hSize = HUF_readDTableX1_wksp_bmi2(dctx, cSrc, cSrcSize, workSpace, wkspSize, bmi2);
795     if (HUF_isError(hSize)) return hSize;
796     if (hSize >= cSrcSize) return ERROR(srcSize_wrong);
797     ip += hSize; cSrcSize -= hSize;
798 
799     return HUF_decompress4X1_usingDTable_internal(dst, dstSize, ip, cSrcSize, dctx, bmi2);
800 }
801 
802 size_t HUF_decompress4X1_DCtx_wksp(HUF_DTable* dctx, void* dst, size_t dstSize,
803                                    const void* cSrc, size_t cSrcSize,
804                                    void* workSpace, size_t wkspSize)
805 {
806     return HUF_decompress4X1_DCtx_wksp_bmi2(dctx, dst, dstSize, cSrc, cSrcSize, workSpace, wkspSize, 0);
807 }
808 
809 
810 #endif /* HUF_FORCE_DECOMPRESS_X2 */
811 
812 
813 #ifndef HUF_FORCE_DECOMPRESS_X1
814 
815 /* *************************/
816 /* double-symbols decoding */
817 /* *************************/
818 
819 typedef struct { U16 sequence; BYTE nbBits; BYTE length; } HUF_DEltX2;  /* double-symbols decoding */
820 typedef struct { BYTE symbol; } sortedSymbol_t;
821 typedef U32 rankValCol_t[HUF_TABLELOG_MAX + 1];
822 typedef rankValCol_t rankVal_t[HUF_TABLELOG_MAX];
823 
824 /**
825  * Constructs a HUF_DEltX2 in a U32.
826  */
827 static U32 HUF_buildDEltX2U32(U32 symbol, U32 nbBits, U32 baseSeq, int level)
828 {
829     U32 seq;
830     DEBUG_STATIC_ASSERT(offsetof(HUF_DEltX2, sequence) == 0);
831     DEBUG_STATIC_ASSERT(offsetof(HUF_DEltX2, nbBits) == 2);
832     DEBUG_STATIC_ASSERT(offsetof(HUF_DEltX2, length) == 3);
833     DEBUG_STATIC_ASSERT(sizeof(HUF_DEltX2) == sizeof(U32));
834     if (MEM_isLittleEndian()) {
835         seq = level == 1 ? symbol : (baseSeq + (symbol << 8));
836         return seq + (nbBits << 16) + ((U32)level << 24);
837     } else {
838         seq = level == 1 ? (symbol << 8) : ((baseSeq << 8) + symbol);
839         return (seq << 16) + (nbBits << 8) + (U32)level;
840     }
841 }
842 
843 /**
844  * Constructs a HUF_DEltX2.
845  */
846 static HUF_DEltX2 HUF_buildDEltX2(U32 symbol, U32 nbBits, U32 baseSeq, int level)
847 {
848     HUF_DEltX2 DElt;
849     U32 const val = HUF_buildDEltX2U32(symbol, nbBits, baseSeq, level);
850     DEBUG_STATIC_ASSERT(sizeof(DElt) == sizeof(val));
851     ZSTD_memcpy(&DElt, &val, sizeof(val));
852     return DElt;
853 }
854 
855 /**
856  * Constructs 2 HUF_DEltX2s and packs them into a U64.
857  */
858 static U64 HUF_buildDEltX2U64(U32 symbol, U32 nbBits, U16 baseSeq, int level)
859 {
860     U32 DElt = HUF_buildDEltX2U32(symbol, nbBits, baseSeq, level);
861     return (U64)DElt + ((U64)DElt << 32);
862 }
863 
864 /**
865  * Fills the DTable rank with all the symbols from [begin, end) that are each
866  * nbBits long.
867  *
868  * @param DTableRank The start of the rank in the DTable.
869  * @param begin The first symbol to fill (inclusive).
870  * @param end The last symbol to fill (exclusive).
871  * @param nbBits Each symbol is nbBits long.
872  * @param tableLog The table log.
873  * @param baseSeq If level == 1 { 0 } else { the first level symbol }
874  * @param level The level in the table. Must be 1 or 2.
875  */
876 static void HUF_fillDTableX2ForWeight(
877     HUF_DEltX2* DTableRank,
878     sortedSymbol_t const* begin, sortedSymbol_t const* end,
879     U32 nbBits, U32 tableLog,
880     U16 baseSeq, int const level)
881 {
882     U32 const length = 1U << ((tableLog - nbBits) & 0x1F /* quiet static-analyzer */);
883     const sortedSymbol_t* ptr;
884     assert(level >= 1 && level <= 2);
885     switch (length) {
886     case 1:
887         for (ptr = begin; ptr != end; ++ptr) {
888             HUF_DEltX2 const DElt = HUF_buildDEltX2(ptr->symbol, nbBits, baseSeq, level);
889             *DTableRank++ = DElt;
890         }
891         break;
892     case 2:
893         for (ptr = begin; ptr != end; ++ptr) {
894             HUF_DEltX2 const DElt = HUF_buildDEltX2(ptr->symbol, nbBits, baseSeq, level);
895             DTableRank[0] = DElt;
896             DTableRank[1] = DElt;
897             DTableRank += 2;
898         }
899         break;
900     case 4:
901         for (ptr = begin; ptr != end; ++ptr) {
902             U64 const DEltX2 = HUF_buildDEltX2U64(ptr->symbol, nbBits, baseSeq, level);
903             ZSTD_memcpy(DTableRank + 0, &DEltX2, sizeof(DEltX2));
904             ZSTD_memcpy(DTableRank + 2, &DEltX2, sizeof(DEltX2));
905             DTableRank += 4;
906         }
907         break;
908     case 8:
909         for (ptr = begin; ptr != end; ++ptr) {
910             U64 const DEltX2 = HUF_buildDEltX2U64(ptr->symbol, nbBits, baseSeq, level);
911             ZSTD_memcpy(DTableRank + 0, &DEltX2, sizeof(DEltX2));
912             ZSTD_memcpy(DTableRank + 2, &DEltX2, sizeof(DEltX2));
913             ZSTD_memcpy(DTableRank + 4, &DEltX2, sizeof(DEltX2));
914             ZSTD_memcpy(DTableRank + 6, &DEltX2, sizeof(DEltX2));
915             DTableRank += 8;
916         }
917         break;
918     default:
919         for (ptr = begin; ptr != end; ++ptr) {
920             U64 const DEltX2 = HUF_buildDEltX2U64(ptr->symbol, nbBits, baseSeq, level);
921             HUF_DEltX2* const DTableRankEnd = DTableRank + length;
922             for (; DTableRank != DTableRankEnd; DTableRank += 8) {
923                 ZSTD_memcpy(DTableRank + 0, &DEltX2, sizeof(DEltX2));
924                 ZSTD_memcpy(DTableRank + 2, &DEltX2, sizeof(DEltX2));
925                 ZSTD_memcpy(DTableRank + 4, &DEltX2, sizeof(DEltX2));
926                 ZSTD_memcpy(DTableRank + 6, &DEltX2, sizeof(DEltX2));
927             }
928         }
929         break;
930     }
931 }
932 
933 /* HUF_fillDTableX2Level2() :
934  * `rankValOrigin` must be a table of at least (HUF_TABLELOG_MAX + 1) U32 */
935 static void HUF_fillDTableX2Level2(HUF_DEltX2* DTable, U32 targetLog, const U32 consumedBits,
936                            const U32* rankVal, const int minWeight, const int maxWeight1,
937                            const sortedSymbol_t* sortedSymbols, U32 const* rankStart,
938                            U32 nbBitsBaseline, U16 baseSeq)
939 {
940     /* Fill skipped values (all positions up to rankVal[minWeight]).
941      * These are positions only get a single symbol because the combined weight
942      * is too large.
943      */
944     if (minWeight>1) {
945         U32 const length = 1U << ((targetLog - consumedBits) & 0x1F /* quiet static-analyzer */);
946         U64 const DEltX2 = HUF_buildDEltX2U64(baseSeq, consumedBits, /* baseSeq */ 0, /* level */ 1);
947         int const skipSize = rankVal[minWeight];
948         assert(length > 1);
949         assert((U32)skipSize < length);
950         switch (length) {
951         case 2:
952             assert(skipSize == 1);
953             ZSTD_memcpy(DTable, &DEltX2, sizeof(DEltX2));
954             break;
955         case 4:
956             assert(skipSize <= 4);
957             ZSTD_memcpy(DTable + 0, &DEltX2, sizeof(DEltX2));
958             ZSTD_memcpy(DTable + 2, &DEltX2, sizeof(DEltX2));
959             break;
960         default:
961             {
962                 int i;
963                 for (i = 0; i < skipSize; i += 8) {
964                     ZSTD_memcpy(DTable + i + 0, &DEltX2, sizeof(DEltX2));
965                     ZSTD_memcpy(DTable + i + 2, &DEltX2, sizeof(DEltX2));
966                     ZSTD_memcpy(DTable + i + 4, &DEltX2, sizeof(DEltX2));
967                     ZSTD_memcpy(DTable + i + 6, &DEltX2, sizeof(DEltX2));
968                 }
969             }
970         }
971     }
972 
973     /* Fill each of the second level symbols by weight. */
974     {
975         int w;
976         for (w = minWeight; w < maxWeight1; ++w) {
977             int const begin = rankStart[w];
978             int const end = rankStart[w+1];
979             U32 const nbBits = nbBitsBaseline - w;
980             U32 const totalBits = nbBits + consumedBits;
981             HUF_fillDTableX2ForWeight(
982                 DTable + rankVal[w],
983                 sortedSymbols + begin, sortedSymbols + end,
984                 totalBits, targetLog,
985                 baseSeq, /* level */ 2);
986         }
987     }
988 }
989 
990 static void HUF_fillDTableX2(HUF_DEltX2* DTable, const U32 targetLog,
991                            const sortedSymbol_t* sortedList,
992                            const U32* rankStart, rankVal_t rankValOrigin, const U32 maxWeight,
993                            const U32 nbBitsBaseline)
994 {
995     U32* const rankVal = rankValOrigin[0];
996     const int scaleLog = nbBitsBaseline - targetLog;   /* note : targetLog >= srcLog, hence scaleLog <= 1 */
997     const U32 minBits  = nbBitsBaseline - maxWeight;
998     int w;
999     int const wEnd = (int)maxWeight + 1;
1000 
1001     /* Fill DTable in order of weight. */
1002     for (w = 1; w < wEnd; ++w) {
1003         int const begin = (int)rankStart[w];
1004         int const end = (int)rankStart[w+1];
1005         U32 const nbBits = nbBitsBaseline - w;
1006 
1007         if (targetLog-nbBits >= minBits) {
1008             /* Enough room for a second symbol. */
1009             int start = rankVal[w];
1010             U32 const length = 1U << ((targetLog - nbBits) & 0x1F /* quiet static-analyzer */);
1011             int minWeight = nbBits + scaleLog;
1012             int s;
1013             if (minWeight < 1) minWeight = 1;
1014             /* Fill the DTable for every symbol of weight w.
1015              * These symbols get at least 1 second symbol.
1016              */
1017             for (s = begin; s != end; ++s) {
1018                 HUF_fillDTableX2Level2(
1019                     DTable + start, targetLog, nbBits,
1020                     rankValOrigin[nbBits], minWeight, wEnd,
1021                     sortedList, rankStart,
1022                     nbBitsBaseline, sortedList[s].symbol);
1023                 start += length;
1024             }
1025         } else {
1026             /* Only a single symbol. */
1027             HUF_fillDTableX2ForWeight(
1028                 DTable + rankVal[w],
1029                 sortedList + begin, sortedList + end,
1030                 nbBits, targetLog,
1031                 /* baseSeq */ 0, /* level */ 1);
1032         }
1033     }
1034 }
1035 
1036 typedef struct {
1037     rankValCol_t rankVal[HUF_TABLELOG_MAX];
1038     U32 rankStats[HUF_TABLELOG_MAX + 1];
1039     U32 rankStart0[HUF_TABLELOG_MAX + 3];
1040     sortedSymbol_t sortedSymbol[HUF_SYMBOLVALUE_MAX + 1];
1041     BYTE weightList[HUF_SYMBOLVALUE_MAX + 1];
1042     U32 calleeWksp[HUF_READ_STATS_WORKSPACE_SIZE_U32];
1043 } HUF_ReadDTableX2_Workspace;
1044 
1045 size_t HUF_readDTableX2_wksp(HUF_DTable* DTable,
1046                        const void* src, size_t srcSize,
1047                              void* workSpace, size_t wkspSize)
1048 {
1049     return HUF_readDTableX2_wksp_bmi2(DTable, src, srcSize, workSpace, wkspSize, /* bmi2 */ 0);
1050 }
1051 
1052 size_t HUF_readDTableX2_wksp_bmi2(HUF_DTable* DTable,
1053                        const void* src, size_t srcSize,
1054                              void* workSpace, size_t wkspSize, int bmi2)
1055 {
1056     U32 tableLog, maxW, nbSymbols;
1057     DTableDesc dtd = HUF_getDTableDesc(DTable);
1058     U32 maxTableLog = dtd.maxTableLog;
1059     size_t iSize;
1060     void* dtPtr = DTable+1;   /* force compiler to avoid strict-aliasing */
1061     HUF_DEltX2* const dt = (HUF_DEltX2*)dtPtr;
1062     U32 *rankStart;
1063 
1064     HUF_ReadDTableX2_Workspace* const wksp = (HUF_ReadDTableX2_Workspace*)workSpace;
1065 
1066     if (sizeof(*wksp) > wkspSize) return ERROR(GENERIC);
1067 
1068     rankStart = wksp->rankStart0 + 1;
1069     ZSTD_memset(wksp->rankStats, 0, sizeof(wksp->rankStats));
1070     ZSTD_memset(wksp->rankStart0, 0, sizeof(wksp->rankStart0));
1071 
1072     DEBUG_STATIC_ASSERT(sizeof(HUF_DEltX2) == sizeof(HUF_DTable));   /* if compiler fails here, assertion is wrong */
1073     if (maxTableLog > HUF_TABLELOG_MAX) return ERROR(tableLog_tooLarge);
1074     /* ZSTD_memset(weightList, 0, sizeof(weightList)); */  /* is not necessary, even though some analyzer complain ... */
1075 
1076     iSize = HUF_readStats_wksp(wksp->weightList, HUF_SYMBOLVALUE_MAX + 1, wksp->rankStats, &nbSymbols, &tableLog, src, srcSize, wksp->calleeWksp, sizeof(wksp->calleeWksp), bmi2);
1077     if (HUF_isError(iSize)) return iSize;
1078 
1079     /* check result */
1080     if (tableLog > maxTableLog) return ERROR(tableLog_tooLarge);   /* DTable can't fit code depth */
1081     if (tableLog <= HUF_DECODER_FAST_TABLELOG && maxTableLog > HUF_DECODER_FAST_TABLELOG) maxTableLog = HUF_DECODER_FAST_TABLELOG;
1082 
1083     /* find maxWeight */
1084     for (maxW = tableLog; wksp->rankStats[maxW]==0; maxW--) {}  /* necessarily finds a solution before 0 */
1085 
1086     /* Get start index of each weight */
1087     {   U32 w, nextRankStart = 0;
1088         for (w=1; w<maxW+1; w++) {
1089             U32 curr = nextRankStart;
1090             nextRankStart += wksp->rankStats[w];
1091             rankStart[w] = curr;
1092         }
1093         rankStart[0] = nextRankStart;   /* put all 0w symbols at the end of sorted list*/
1094         rankStart[maxW+1] = nextRankStart;
1095     }
1096 
1097     /* sort symbols by weight */
1098     {   U32 s;
1099         for (s=0; s<nbSymbols; s++) {
1100             U32 const w = wksp->weightList[s];
1101             U32 const r = rankStart[w]++;
1102             wksp->sortedSymbol[r].symbol = (BYTE)s;
1103         }
1104         rankStart[0] = 0;   /* forget 0w symbols; this is beginning of weight(1) */
1105     }
1106 
1107     /* Build rankVal */
1108     {   U32* const rankVal0 = wksp->rankVal[0];
1109         {   int const rescale = (maxTableLog-tableLog) - 1;   /* tableLog <= maxTableLog */
1110             U32 nextRankVal = 0;
1111             U32 w;
1112             for (w=1; w<maxW+1; w++) {
1113                 U32 curr = nextRankVal;
1114                 nextRankVal += wksp->rankStats[w] << (w+rescale);
1115                 rankVal0[w] = curr;
1116         }   }
1117         {   U32 const minBits = tableLog+1 - maxW;
1118             U32 consumed;
1119             for (consumed = minBits; consumed < maxTableLog - minBits + 1; consumed++) {
1120                 U32* const rankValPtr = wksp->rankVal[consumed];
1121                 U32 w;
1122                 for (w = 1; w < maxW+1; w++) {
1123                     rankValPtr[w] = rankVal0[w] >> consumed;
1124     }   }   }   }
1125 
1126     HUF_fillDTableX2(dt, maxTableLog,
1127                    wksp->sortedSymbol,
1128                    wksp->rankStart0, wksp->rankVal, maxW,
1129                    tableLog+1);
1130 
1131     dtd.tableLog = (BYTE)maxTableLog;
1132     dtd.tableType = 1;
1133     ZSTD_memcpy(DTable, &dtd, sizeof(dtd));
1134     return iSize;
1135 }
1136 
1137 
1138 FORCE_INLINE_TEMPLATE U32
1139 HUF_decodeSymbolX2(void* op, BIT_DStream_t* DStream, const HUF_DEltX2* dt, const U32 dtLog)
1140 {
1141     size_t const val = BIT_lookBitsFast(DStream, dtLog);   /* note : dtLog >= 1 */
1142     ZSTD_memcpy(op, &dt[val].sequence, 2);
1143     BIT_skipBits(DStream, dt[val].nbBits);
1144     return dt[val].length;
1145 }
1146 
1147 FORCE_INLINE_TEMPLATE U32
1148 HUF_decodeLastSymbolX2(void* op, BIT_DStream_t* DStream, const HUF_DEltX2* dt, const U32 dtLog)
1149 {
1150     size_t const val = BIT_lookBitsFast(DStream, dtLog);   /* note : dtLog >= 1 */
1151     ZSTD_memcpy(op, &dt[val].sequence, 1);
1152     if (dt[val].length==1) {
1153         BIT_skipBits(DStream, dt[val].nbBits);
1154     } else {
1155         if (DStream->bitsConsumed < (sizeof(DStream->bitContainer)*8)) {
1156             BIT_skipBits(DStream, dt[val].nbBits);
1157             if (DStream->bitsConsumed > (sizeof(DStream->bitContainer)*8))
1158                 /* ugly hack; works only because it's the last symbol. Note : can't easily extract nbBits from just this symbol */
1159                 DStream->bitsConsumed = (sizeof(DStream->bitContainer)*8);
1160         }
1161     }
1162     return 1;
1163 }
1164 
1165 #define HUF_DECODE_SYMBOLX2_0(ptr, DStreamPtr) \
1166     ptr += HUF_decodeSymbolX2(ptr, DStreamPtr, dt, dtLog)
1167 
1168 #define HUF_DECODE_SYMBOLX2_1(ptr, DStreamPtr) \
1169     if (MEM_64bits() || (HUF_TABLELOG_MAX<=12)) \
1170         ptr += HUF_decodeSymbolX2(ptr, DStreamPtr, dt, dtLog)
1171 
1172 #define HUF_DECODE_SYMBOLX2_2(ptr, DStreamPtr) \
1173     if (MEM_64bits()) \
1174         ptr += HUF_decodeSymbolX2(ptr, DStreamPtr, dt, dtLog)
1175 
1176 HINT_INLINE size_t
1177 HUF_decodeStreamX2(BYTE* p, BIT_DStream_t* bitDPtr, BYTE* const pEnd,
1178                 const HUF_DEltX2* const dt, const U32 dtLog)
1179 {
1180     BYTE* const pStart = p;
1181 
1182     /* up to 8 symbols at a time */
1183     if ((size_t)(pEnd - p) >= sizeof(bitDPtr->bitContainer)) {
1184         if (dtLog <= 11 && MEM_64bits()) {
1185             /* up to 10 symbols at a time */
1186             while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) & (p < pEnd-9)) {
1187                 HUF_DECODE_SYMBOLX2_0(p, bitDPtr);
1188                 HUF_DECODE_SYMBOLX2_0(p, bitDPtr);
1189                 HUF_DECODE_SYMBOLX2_0(p, bitDPtr);
1190                 HUF_DECODE_SYMBOLX2_0(p, bitDPtr);
1191                 HUF_DECODE_SYMBOLX2_0(p, bitDPtr);
1192             }
1193         } else {
1194             /* up to 8 symbols at a time */
1195             while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) & (p < pEnd-(sizeof(bitDPtr->bitContainer)-1))) {
1196                 HUF_DECODE_SYMBOLX2_2(p, bitDPtr);
1197                 HUF_DECODE_SYMBOLX2_1(p, bitDPtr);
1198                 HUF_DECODE_SYMBOLX2_2(p, bitDPtr);
1199                 HUF_DECODE_SYMBOLX2_0(p, bitDPtr);
1200             }
1201         }
1202     } else {
1203         BIT_reloadDStream(bitDPtr);
1204     }
1205 
1206     /* closer to end : up to 2 symbols at a time */
1207     if ((size_t)(pEnd - p) >= 2) {
1208         while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) & (p <= pEnd-2))
1209             HUF_DECODE_SYMBOLX2_0(p, bitDPtr);
1210 
1211         while (p <= pEnd-2)
1212             HUF_DECODE_SYMBOLX2_0(p, bitDPtr);   /* no need to reload : reached the end of DStream */
1213     }
1214 
1215     if (p < pEnd)
1216         p += HUF_decodeLastSymbolX2(p, bitDPtr, dt, dtLog);
1217 
1218     return p-pStart;
1219 }
1220 
1221 FORCE_INLINE_TEMPLATE size_t
1222 HUF_decompress1X2_usingDTable_internal_body(
1223           void* dst,  size_t dstSize,
1224     const void* cSrc, size_t cSrcSize,
1225     const HUF_DTable* DTable)
1226 {
1227     BIT_DStream_t bitD;
1228 
1229     /* Init */
1230     CHECK_F( BIT_initDStream(&bitD, cSrc, cSrcSize) );
1231 
1232     /* decode */
1233     {   BYTE* const ostart = (BYTE*) dst;
1234         BYTE* const oend = ostart + dstSize;
1235         const void* const dtPtr = DTable+1;   /* force compiler to not use strict-aliasing */
1236         const HUF_DEltX2* const dt = (const HUF_DEltX2*)dtPtr;
1237         DTableDesc const dtd = HUF_getDTableDesc(DTable);
1238         HUF_decodeStreamX2(ostart, &bitD, oend, dt, dtd.tableLog);
1239     }
1240 
1241     /* check */
1242     if (!BIT_endOfDStream(&bitD)) return ERROR(corruption_detected);
1243 
1244     /* decoded size */
1245     return dstSize;
1246 }
1247 FORCE_INLINE_TEMPLATE size_t
1248 HUF_decompress4X2_usingDTable_internal_body(
1249           void* dst,  size_t dstSize,
1250     const void* cSrc, size_t cSrcSize,
1251     const HUF_DTable* DTable)
1252 {
1253     if (cSrcSize < 10) return ERROR(corruption_detected);   /* strict minimum : jump table + 1 byte per stream */
1254 
1255     {   const BYTE* const istart = (const BYTE*) cSrc;
1256         BYTE* const ostart = (BYTE*) dst;
1257         BYTE* const oend = ostart + dstSize;
1258         BYTE* const olimit = oend - (sizeof(size_t)-1);
1259         const void* const dtPtr = DTable+1;
1260         const HUF_DEltX2* const dt = (const HUF_DEltX2*)dtPtr;
1261 
1262         /* Init */
1263         BIT_DStream_t bitD1;
1264         BIT_DStream_t bitD2;
1265         BIT_DStream_t bitD3;
1266         BIT_DStream_t bitD4;
1267         size_t const length1 = MEM_readLE16(istart);
1268         size_t const length2 = MEM_readLE16(istart+2);
1269         size_t const length3 = MEM_readLE16(istart+4);
1270         size_t const length4 = cSrcSize - (length1 + length2 + length3 + 6);
1271         const BYTE* const istart1 = istart + 6;  /* jumpTable */
1272         const BYTE* const istart2 = istart1 + length1;
1273         const BYTE* const istart3 = istart2 + length2;
1274         const BYTE* const istart4 = istart3 + length3;
1275         size_t const segmentSize = (dstSize+3) / 4;
1276         BYTE* const opStart2 = ostart + segmentSize;
1277         BYTE* const opStart3 = opStart2 + segmentSize;
1278         BYTE* const opStart4 = opStart3 + segmentSize;
1279         BYTE* op1 = ostart;
1280         BYTE* op2 = opStart2;
1281         BYTE* op3 = opStart3;
1282         BYTE* op4 = opStart4;
1283         U32 endSignal = 1;
1284         DTableDesc const dtd = HUF_getDTableDesc(DTable);
1285         U32 const dtLog = dtd.tableLog;
1286 
1287         if (length4 > cSrcSize) return ERROR(corruption_detected);   /* overflow */
1288         if (opStart4 > oend) return ERROR(corruption_detected);      /* overflow */
1289         CHECK_F( BIT_initDStream(&bitD1, istart1, length1) );
1290         CHECK_F( BIT_initDStream(&bitD2, istart2, length2) );
1291         CHECK_F( BIT_initDStream(&bitD3, istart3, length3) );
1292         CHECK_F( BIT_initDStream(&bitD4, istart4, length4) );
1293 
1294         /* 16-32 symbols per loop (4-8 symbols per stream) */
1295         if ((size_t)(oend - op4) >= sizeof(size_t)) {
1296             for ( ; (endSignal) & (op4 < olimit); ) {
1297 #if defined(__clang__) && (defined(__x86_64__) || defined(__i386__))
1298                 HUF_DECODE_SYMBOLX2_2(op1, &bitD1);
1299                 HUF_DECODE_SYMBOLX2_1(op1, &bitD1);
1300                 HUF_DECODE_SYMBOLX2_2(op1, &bitD1);
1301                 HUF_DECODE_SYMBOLX2_0(op1, &bitD1);
1302                 HUF_DECODE_SYMBOLX2_2(op2, &bitD2);
1303                 HUF_DECODE_SYMBOLX2_1(op2, &bitD2);
1304                 HUF_DECODE_SYMBOLX2_2(op2, &bitD2);
1305                 HUF_DECODE_SYMBOLX2_0(op2, &bitD2);
1306                 endSignal &= BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished;
1307                 endSignal &= BIT_reloadDStreamFast(&bitD2) == BIT_DStream_unfinished;
1308                 HUF_DECODE_SYMBOLX2_2(op3, &bitD3);
1309                 HUF_DECODE_SYMBOLX2_1(op3, &bitD3);
1310                 HUF_DECODE_SYMBOLX2_2(op3, &bitD3);
1311                 HUF_DECODE_SYMBOLX2_0(op3, &bitD3);
1312                 HUF_DECODE_SYMBOLX2_2(op4, &bitD4);
1313                 HUF_DECODE_SYMBOLX2_1(op4, &bitD4);
1314                 HUF_DECODE_SYMBOLX2_2(op4, &bitD4);
1315                 HUF_DECODE_SYMBOLX2_0(op4, &bitD4);
1316                 endSignal &= BIT_reloadDStreamFast(&bitD3) == BIT_DStream_unfinished;
1317                 endSignal &= BIT_reloadDStreamFast(&bitD4) == BIT_DStream_unfinished;
1318 #else
1319                 HUF_DECODE_SYMBOLX2_2(op1, &bitD1);
1320                 HUF_DECODE_SYMBOLX2_2(op2, &bitD2);
1321                 HUF_DECODE_SYMBOLX2_2(op3, &bitD3);
1322                 HUF_DECODE_SYMBOLX2_2(op4, &bitD4);
1323                 HUF_DECODE_SYMBOLX2_1(op1, &bitD1);
1324                 HUF_DECODE_SYMBOLX2_1(op2, &bitD2);
1325                 HUF_DECODE_SYMBOLX2_1(op3, &bitD3);
1326                 HUF_DECODE_SYMBOLX2_1(op4, &bitD4);
1327                 HUF_DECODE_SYMBOLX2_2(op1, &bitD1);
1328                 HUF_DECODE_SYMBOLX2_2(op2, &bitD2);
1329                 HUF_DECODE_SYMBOLX2_2(op3, &bitD3);
1330                 HUF_DECODE_SYMBOLX2_2(op4, &bitD4);
1331                 HUF_DECODE_SYMBOLX2_0(op1, &bitD1);
1332                 HUF_DECODE_SYMBOLX2_0(op2, &bitD2);
1333                 HUF_DECODE_SYMBOLX2_0(op3, &bitD3);
1334                 HUF_DECODE_SYMBOLX2_0(op4, &bitD4);
1335                 endSignal = (U32)LIKELY((U32)
1336                             (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished)
1337                         & (BIT_reloadDStreamFast(&bitD2) == BIT_DStream_unfinished)
1338                         & (BIT_reloadDStreamFast(&bitD3) == BIT_DStream_unfinished)
1339                         & (BIT_reloadDStreamFast(&bitD4) == BIT_DStream_unfinished));
1340 #endif
1341             }
1342         }
1343 
1344         /* check corruption */
1345         if (op1 > opStart2) return ERROR(corruption_detected);
1346         if (op2 > opStart3) return ERROR(corruption_detected);
1347         if (op3 > opStart4) return ERROR(corruption_detected);
1348         /* note : op4 already verified within main loop */
1349 
1350         /* finish bitStreams one by one */
1351         HUF_decodeStreamX2(op1, &bitD1, opStart2, dt, dtLog);
1352         HUF_decodeStreamX2(op2, &bitD2, opStart3, dt, dtLog);
1353         HUF_decodeStreamX2(op3, &bitD3, opStart4, dt, dtLog);
1354         HUF_decodeStreamX2(op4, &bitD4, oend,     dt, dtLog);
1355 
1356         /* check */
1357         { U32 const endCheck = BIT_endOfDStream(&bitD1) & BIT_endOfDStream(&bitD2) & BIT_endOfDStream(&bitD3) & BIT_endOfDStream(&bitD4);
1358           if (!endCheck) return ERROR(corruption_detected); }
1359 
1360         /* decoded size */
1361         return dstSize;
1362     }
1363 }
1364 
1365 #if HUF_NEED_BMI2_FUNCTION
1366 static BMI2_TARGET_ATTRIBUTE
1367 size_t HUF_decompress4X2_usingDTable_internal_bmi2(void* dst, size_t dstSize, void const* cSrc,
1368                     size_t cSrcSize, HUF_DTable const* DTable) {
1369     return HUF_decompress4X2_usingDTable_internal_body(dst, dstSize, cSrc, cSrcSize, DTable);
1370 }
1371 #endif
1372 
1373 #if HUF_NEED_DEFAULT_FUNCTION
1374 static
1375 size_t HUF_decompress4X2_usingDTable_internal_default(void* dst, size_t dstSize, void const* cSrc,
1376                     size_t cSrcSize, HUF_DTable const* DTable) {
1377     return HUF_decompress4X2_usingDTable_internal_body(dst, dstSize, cSrc, cSrcSize, DTable);
1378 }
1379 #endif
1380 
1381 #if ZSTD_ENABLE_ASM_X86_64_BMI2
1382 
1383 HUF_ASM_DECL void HUF_decompress4X2_usingDTable_internal_bmi2_asm_loop(HUF_DecompressAsmArgs* args) ZSTDLIB_HIDDEN;
1384 
1385 static HUF_ASM_X86_64_BMI2_ATTRS size_t
1386 HUF_decompress4X2_usingDTable_internal_bmi2_asm(
1387           void* dst,  size_t dstSize,
1388     const void* cSrc, size_t cSrcSize,
1389     const HUF_DTable* DTable) {
1390     void const* dt = DTable + 1;
1391     const BYTE* const iend = (const BYTE*)cSrc + 6;
1392     BYTE* const oend = (BYTE*)dst + dstSize;
1393     HUF_DecompressAsmArgs args;
1394     {
1395         size_t const ret = HUF_DecompressAsmArgs_init(&args, dst, dstSize, cSrc, cSrcSize, DTable);
1396         FORWARD_IF_ERROR(ret, "Failed to init asm args");
1397         if (ret != 0)
1398             return HUF_decompress4X2_usingDTable_internal_bmi2(dst, dstSize, cSrc, cSrcSize, DTable);
1399     }
1400 
1401     assert(args.ip[0] >= args.ilimit);
1402     HUF_decompress4X2_usingDTable_internal_bmi2_asm_loop(&args);
1403 
1404     /* note : op4 already verified within main loop */
1405     assert(args.ip[0] >= iend);
1406     assert(args.ip[1] >= iend);
1407     assert(args.ip[2] >= iend);
1408     assert(args.ip[3] >= iend);
1409     assert(args.op[3] <= oend);
1410     (void)iend;
1411 
1412     /* finish bitStreams one by one */
1413     {
1414         size_t const segmentSize = (dstSize+3) / 4;
1415         BYTE* segmentEnd = (BYTE*)dst;
1416         int i;
1417         for (i = 0; i < 4; ++i) {
1418             BIT_DStream_t bit;
1419             if (segmentSize <= (size_t)(oend - segmentEnd))
1420                 segmentEnd += segmentSize;
1421             else
1422                 segmentEnd = oend;
1423             FORWARD_IF_ERROR(HUF_initRemainingDStream(&bit, &args, i, segmentEnd), "corruption");
1424             args.op[i] += HUF_decodeStreamX2(args.op[i], &bit, segmentEnd, (HUF_DEltX2 const*)dt, HUF_DECODER_FAST_TABLELOG);
1425             if (args.op[i] != segmentEnd)
1426                 return ERROR(corruption_detected);
1427         }
1428     }
1429 
1430     /* decoded size */
1431     return dstSize;
1432 }
1433 #endif /* ZSTD_ENABLE_ASM_X86_64_BMI2 */
1434 
1435 static size_t HUF_decompress4X2_usingDTable_internal(void* dst, size_t dstSize, void const* cSrc,
1436                     size_t cSrcSize, HUF_DTable const* DTable, int bmi2)
1437 {
1438 #if DYNAMIC_BMI2
1439     if (bmi2) {
1440 # if ZSTD_ENABLE_ASM_X86_64_BMI2
1441         return HUF_decompress4X2_usingDTable_internal_bmi2_asm(dst, dstSize, cSrc, cSrcSize, DTable);
1442 # else
1443         return HUF_decompress4X2_usingDTable_internal_bmi2(dst, dstSize, cSrc, cSrcSize, DTable);
1444 # endif
1445     }
1446 #else
1447     (void)bmi2;
1448 #endif
1449 
1450 #if ZSTD_ENABLE_ASM_X86_64_BMI2 && defined(__BMI2__)
1451     return HUF_decompress4X2_usingDTable_internal_bmi2_asm(dst, dstSize, cSrc, cSrcSize, DTable);
1452 #else
1453     return HUF_decompress4X2_usingDTable_internal_default(dst, dstSize, cSrc, cSrcSize, DTable);
1454 #endif
1455 }
1456 
1457 HUF_DGEN(HUF_decompress1X2_usingDTable_internal)
1458 
1459 size_t HUF_decompress1X2_usingDTable(
1460           void* dst,  size_t dstSize,
1461     const void* cSrc, size_t cSrcSize,
1462     const HUF_DTable* DTable)
1463 {
1464     DTableDesc dtd = HUF_getDTableDesc(DTable);
1465     if (dtd.tableType != 1) return ERROR(GENERIC);
1466     return HUF_decompress1X2_usingDTable_internal(dst, dstSize, cSrc, cSrcSize, DTable, /* bmi2 */ 0);
1467 }
1468 
1469 size_t HUF_decompress1X2_DCtx_wksp(HUF_DTable* DCtx, void* dst, size_t dstSize,
1470                                    const void* cSrc, size_t cSrcSize,
1471                                    void* workSpace, size_t wkspSize)
1472 {
1473     const BYTE* ip = (const BYTE*) cSrc;
1474 
1475     size_t const hSize = HUF_readDTableX2_wksp(DCtx, cSrc, cSrcSize,
1476                                                workSpace, wkspSize);
1477     if (HUF_isError(hSize)) return hSize;
1478     if (hSize >= cSrcSize) return ERROR(srcSize_wrong);
1479     ip += hSize; cSrcSize -= hSize;
1480 
1481     return HUF_decompress1X2_usingDTable_internal(dst, dstSize, ip, cSrcSize, DCtx, /* bmi2 */ 0);
1482 }
1483 
1484 
1485 size_t HUF_decompress4X2_usingDTable(
1486           void* dst,  size_t dstSize,
1487     const void* cSrc, size_t cSrcSize,
1488     const HUF_DTable* DTable)
1489 {
1490     DTableDesc dtd = HUF_getDTableDesc(DTable);
1491     if (dtd.tableType != 1) return ERROR(GENERIC);
1492     return HUF_decompress4X2_usingDTable_internal(dst, dstSize, cSrc, cSrcSize, DTable, /* bmi2 */ 0);
1493 }
1494 
1495 static size_t HUF_decompress4X2_DCtx_wksp_bmi2(HUF_DTable* dctx, void* dst, size_t dstSize,
1496                                    const void* cSrc, size_t cSrcSize,
1497                                    void* workSpace, size_t wkspSize, int bmi2)
1498 {
1499     const BYTE* ip = (const BYTE*) cSrc;
1500 
1501     size_t hSize = HUF_readDTableX2_wksp(dctx, cSrc, cSrcSize,
1502                                          workSpace, wkspSize);
1503     if (HUF_isError(hSize)) return hSize;
1504     if (hSize >= cSrcSize) return ERROR(srcSize_wrong);
1505     ip += hSize; cSrcSize -= hSize;
1506 
1507     return HUF_decompress4X2_usingDTable_internal(dst, dstSize, ip, cSrcSize, dctx, bmi2);
1508 }
1509 
1510 size_t HUF_decompress4X2_DCtx_wksp(HUF_DTable* dctx, void* dst, size_t dstSize,
1511                                    const void* cSrc, size_t cSrcSize,
1512                                    void* workSpace, size_t wkspSize)
1513 {
1514     return HUF_decompress4X2_DCtx_wksp_bmi2(dctx, dst, dstSize, cSrc, cSrcSize, workSpace, wkspSize, /* bmi2 */ 0);
1515 }
1516 
1517 
1518 #endif /* HUF_FORCE_DECOMPRESS_X1 */
1519 
1520 
1521 /* ***********************************/
1522 /* Universal decompression selectors */
1523 /* ***********************************/
1524 
1525 size_t HUF_decompress1X_usingDTable(void* dst, size_t maxDstSize,
1526                                     const void* cSrc, size_t cSrcSize,
1527                                     const HUF_DTable* DTable)
1528 {
1529     DTableDesc const dtd = HUF_getDTableDesc(DTable);
1530 #if defined(HUF_FORCE_DECOMPRESS_X1)
1531     (void)dtd;
1532     assert(dtd.tableType == 0);
1533     return HUF_decompress1X1_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, /* bmi2 */ 0);
1534 #elif defined(HUF_FORCE_DECOMPRESS_X2)
1535     (void)dtd;
1536     assert(dtd.tableType == 1);
1537     return HUF_decompress1X2_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, /* bmi2 */ 0);
1538 #else
1539     return dtd.tableType ? HUF_decompress1X2_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, /* bmi2 */ 0) :
1540                            HUF_decompress1X1_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, /* bmi2 */ 0);
1541 #endif
1542 }
1543 
1544 size_t HUF_decompress4X_usingDTable(void* dst, size_t maxDstSize,
1545                                     const void* cSrc, size_t cSrcSize,
1546                                     const HUF_DTable* DTable)
1547 {
1548     DTableDesc const dtd = HUF_getDTableDesc(DTable);
1549 #if defined(HUF_FORCE_DECOMPRESS_X1)
1550     (void)dtd;
1551     assert(dtd.tableType == 0);
1552     return HUF_decompress4X1_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, /* bmi2 */ 0);
1553 #elif defined(HUF_FORCE_DECOMPRESS_X2)
1554     (void)dtd;
1555     assert(dtd.tableType == 1);
1556     return HUF_decompress4X2_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, /* bmi2 */ 0);
1557 #else
1558     return dtd.tableType ? HUF_decompress4X2_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, /* bmi2 */ 0) :
1559                            HUF_decompress4X1_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, /* bmi2 */ 0);
1560 #endif
1561 }
1562 
1563 
1564 #if !defined(HUF_FORCE_DECOMPRESS_X1) && !defined(HUF_FORCE_DECOMPRESS_X2)
1565 typedef struct { U32 tableTime; U32 decode256Time; } algo_time_t;
1566 static const algo_time_t algoTime[16 /* Quantization */][2 /* single, double */] =
1567 {
1568     /* single, double, quad */
1569     {{0,0}, {1,1}},  /* Q==0 : impossible */
1570     {{0,0}, {1,1}},  /* Q==1 : impossible */
1571     {{ 150,216}, { 381,119}},   /* Q == 2 : 12-18% */
1572     {{ 170,205}, { 514,112}},   /* Q == 3 : 18-25% */
1573     {{ 177,199}, { 539,110}},   /* Q == 4 : 25-32% */
1574     {{ 197,194}, { 644,107}},   /* Q == 5 : 32-38% */
1575     {{ 221,192}, { 735,107}},   /* Q == 6 : 38-44% */
1576     {{ 256,189}, { 881,106}},   /* Q == 7 : 44-50% */
1577     {{ 359,188}, {1167,109}},   /* Q == 8 : 50-56% */
1578     {{ 582,187}, {1570,114}},   /* Q == 9 : 56-62% */
1579     {{ 688,187}, {1712,122}},   /* Q ==10 : 62-69% */
1580     {{ 825,186}, {1965,136}},   /* Q ==11 : 69-75% */
1581     {{ 976,185}, {2131,150}},   /* Q ==12 : 75-81% */
1582     {{1180,186}, {2070,175}},   /* Q ==13 : 81-87% */
1583     {{1377,185}, {1731,202}},   /* Q ==14 : 87-93% */
1584     {{1412,185}, {1695,202}},   /* Q ==15 : 93-99% */
1585 };
1586 #endif
1587 
1588 /** HUF_selectDecoder() :
1589  *  Tells which decoder is likely to decode faster,
1590  *  based on a set of pre-computed metrics.
1591  * @return : 0==HUF_decompress4X1, 1==HUF_decompress4X2 .
1592  *  Assumption : 0 < dstSize <= 128 KB */
1593 U32 HUF_selectDecoder (size_t dstSize, size_t cSrcSize)
1594 {
1595     assert(dstSize > 0);
1596     assert(dstSize <= 128*1024);
1597 #if defined(HUF_FORCE_DECOMPRESS_X1)
1598     (void)dstSize;
1599     (void)cSrcSize;
1600     return 0;
1601 #elif defined(HUF_FORCE_DECOMPRESS_X2)
1602     (void)dstSize;
1603     (void)cSrcSize;
1604     return 1;
1605 #else
1606     /* decoder timing evaluation */
1607     {   U32 const Q = (cSrcSize >= dstSize) ? 15 : (U32)(cSrcSize * 16 / dstSize);   /* Q < 16 */
1608         U32 const D256 = (U32)(dstSize >> 8);
1609         U32 const DTime0 = algoTime[Q][0].tableTime + (algoTime[Q][0].decode256Time * D256);
1610         U32 DTime1 = algoTime[Q][1].tableTime + (algoTime[Q][1].decode256Time * D256);
1611         DTime1 += DTime1 >> 5;  /* small advantage to algorithm using less memory, to reduce cache eviction */
1612         return DTime1 < DTime0;
1613     }
1614 #endif
1615 }
1616 
1617 
1618 size_t HUF_decompress4X_hufOnly_wksp(HUF_DTable* dctx, void* dst,
1619                                      size_t dstSize, const void* cSrc,
1620                                      size_t cSrcSize, void* workSpace,
1621                                      size_t wkspSize)
1622 {
1623     /* validation checks */
1624     if (dstSize == 0) return ERROR(dstSize_tooSmall);
1625     if (cSrcSize == 0) return ERROR(corruption_detected);
1626 
1627     {   U32 const algoNb = HUF_selectDecoder(dstSize, cSrcSize);
1628 #if defined(HUF_FORCE_DECOMPRESS_X1)
1629         (void)algoNb;
1630         assert(algoNb == 0);
1631         return HUF_decompress4X1_DCtx_wksp(dctx, dst, dstSize, cSrc, cSrcSize, workSpace, wkspSize);
1632 #elif defined(HUF_FORCE_DECOMPRESS_X2)
1633         (void)algoNb;
1634         assert(algoNb == 1);
1635         return HUF_decompress4X2_DCtx_wksp(dctx, dst, dstSize, cSrc, cSrcSize, workSpace, wkspSize);
1636 #else
1637         return algoNb ? HUF_decompress4X2_DCtx_wksp(dctx, dst, dstSize, cSrc,
1638                             cSrcSize, workSpace, wkspSize):
1639                         HUF_decompress4X1_DCtx_wksp(dctx, dst, dstSize, cSrc, cSrcSize, workSpace, wkspSize);
1640 #endif
1641     }
1642 }
1643 
1644 size_t HUF_decompress1X_DCtx_wksp(HUF_DTable* dctx, void* dst, size_t dstSize,
1645                                   const void* cSrc, size_t cSrcSize,
1646                                   void* workSpace, size_t wkspSize)
1647 {
1648     /* validation checks */
1649     if (dstSize == 0) return ERROR(dstSize_tooSmall);
1650     if (cSrcSize > dstSize) return ERROR(corruption_detected);   /* invalid */
1651     if (cSrcSize == dstSize) { ZSTD_memcpy(dst, cSrc, dstSize); return dstSize; }   /* not compressed */
1652     if (cSrcSize == 1) { ZSTD_memset(dst, *(const BYTE*)cSrc, dstSize); return dstSize; }   /* RLE */
1653 
1654     {   U32 const algoNb = HUF_selectDecoder(dstSize, cSrcSize);
1655 #if defined(HUF_FORCE_DECOMPRESS_X1)
1656         (void)algoNb;
1657         assert(algoNb == 0);
1658         return HUF_decompress1X1_DCtx_wksp(dctx, dst, dstSize, cSrc,
1659                                 cSrcSize, workSpace, wkspSize);
1660 #elif defined(HUF_FORCE_DECOMPRESS_X2)
1661         (void)algoNb;
1662         assert(algoNb == 1);
1663         return HUF_decompress1X2_DCtx_wksp(dctx, dst, dstSize, cSrc,
1664                                 cSrcSize, workSpace, wkspSize);
1665 #else
1666         return algoNb ? HUF_decompress1X2_DCtx_wksp(dctx, dst, dstSize, cSrc,
1667                                 cSrcSize, workSpace, wkspSize):
1668                         HUF_decompress1X1_DCtx_wksp(dctx, dst, dstSize, cSrc,
1669                                 cSrcSize, workSpace, wkspSize);
1670 #endif
1671     }
1672 }
1673 
1674 
1675 size_t HUF_decompress1X_usingDTable_bmi2(void* dst, size_t maxDstSize, const void* cSrc, size_t cSrcSize, const HUF_DTable* DTable, int bmi2)
1676 {
1677     DTableDesc const dtd = HUF_getDTableDesc(DTable);
1678 #if defined(HUF_FORCE_DECOMPRESS_X1)
1679     (void)dtd;
1680     assert(dtd.tableType == 0);
1681     return HUF_decompress1X1_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, bmi2);
1682 #elif defined(HUF_FORCE_DECOMPRESS_X2)
1683     (void)dtd;
1684     assert(dtd.tableType == 1);
1685     return HUF_decompress1X2_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, bmi2);
1686 #else
1687     return dtd.tableType ? HUF_decompress1X2_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, bmi2) :
1688                            HUF_decompress1X1_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, bmi2);
1689 #endif
1690 }
1691 
1692 #ifndef HUF_FORCE_DECOMPRESS_X2
1693 size_t HUF_decompress1X1_DCtx_wksp_bmi2(HUF_DTable* dctx, void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize, void* workSpace, size_t wkspSize, int bmi2)
1694 {
1695     const BYTE* ip = (const BYTE*) cSrc;
1696 
1697     size_t const hSize = HUF_readDTableX1_wksp_bmi2(dctx, cSrc, cSrcSize, workSpace, wkspSize, bmi2);
1698     if (HUF_isError(hSize)) return hSize;
1699     if (hSize >= cSrcSize) return ERROR(srcSize_wrong);
1700     ip += hSize; cSrcSize -= hSize;
1701 
1702     return HUF_decompress1X1_usingDTable_internal(dst, dstSize, ip, cSrcSize, dctx, bmi2);
1703 }
1704 #endif
1705 
1706 size_t HUF_decompress4X_usingDTable_bmi2(void* dst, size_t maxDstSize, const void* cSrc, size_t cSrcSize, const HUF_DTable* DTable, int bmi2)
1707 {
1708     DTableDesc const dtd = HUF_getDTableDesc(DTable);
1709 #if defined(HUF_FORCE_DECOMPRESS_X1)
1710     (void)dtd;
1711     assert(dtd.tableType == 0);
1712     return HUF_decompress4X1_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, bmi2);
1713 #elif defined(HUF_FORCE_DECOMPRESS_X2)
1714     (void)dtd;
1715     assert(dtd.tableType == 1);
1716     return HUF_decompress4X2_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, bmi2);
1717 #else
1718     return dtd.tableType ? HUF_decompress4X2_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, bmi2) :
1719                            HUF_decompress4X1_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable, bmi2);
1720 #endif
1721 }
1722 
1723 size_t HUF_decompress4X_hufOnly_wksp_bmi2(HUF_DTable* dctx, void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize, void* workSpace, size_t wkspSize, int bmi2)
1724 {
1725     /* validation checks */
1726     if (dstSize == 0) return ERROR(dstSize_tooSmall);
1727     if (cSrcSize == 0) return ERROR(corruption_detected);
1728 
1729     {   U32 const algoNb = HUF_selectDecoder(dstSize, cSrcSize);
1730 #if defined(HUF_FORCE_DECOMPRESS_X1)
1731         (void)algoNb;
1732         assert(algoNb == 0);
1733         return HUF_decompress4X1_DCtx_wksp_bmi2(dctx, dst, dstSize, cSrc, cSrcSize, workSpace, wkspSize, bmi2);
1734 #elif defined(HUF_FORCE_DECOMPRESS_X2)
1735         (void)algoNb;
1736         assert(algoNb == 1);
1737         return HUF_decompress4X2_DCtx_wksp_bmi2(dctx, dst, dstSize, cSrc, cSrcSize, workSpace, wkspSize, bmi2);
1738 #else
1739         return algoNb ? HUF_decompress4X2_DCtx_wksp_bmi2(dctx, dst, dstSize, cSrc, cSrcSize, workSpace, wkspSize, bmi2) :
1740                         HUF_decompress4X1_DCtx_wksp_bmi2(dctx, dst, dstSize, cSrc, cSrcSize, workSpace, wkspSize, bmi2);
1741 #endif
1742     }
1743 }
1744 
1745 #ifndef ZSTD_NO_UNUSED_FUNCTIONS
1746 #ifndef HUF_FORCE_DECOMPRESS_X2
1747 size_t HUF_readDTableX1(HUF_DTable* DTable, const void* src, size_t srcSize)
1748 {
1749     U32 workSpace[HUF_DECOMPRESS_WORKSPACE_SIZE_U32];
1750     return HUF_readDTableX1_wksp(DTable, src, srcSize,
1751                                  workSpace, sizeof(workSpace));
1752 }
1753 
1754 size_t HUF_decompress1X1_DCtx(HUF_DTable* DCtx, void* dst, size_t dstSize,
1755                               const void* cSrc, size_t cSrcSize)
1756 {
1757     U32 workSpace[HUF_DECOMPRESS_WORKSPACE_SIZE_U32];
1758     return HUF_decompress1X1_DCtx_wksp(DCtx, dst, dstSize, cSrc, cSrcSize,
1759                                        workSpace, sizeof(workSpace));
1760 }
1761 
1762 size_t HUF_decompress1X1 (void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize)
1763 {
1764     HUF_CREATE_STATIC_DTABLEX1(DTable, HUF_TABLELOG_MAX);
1765     return HUF_decompress1X1_DCtx (DTable, dst, dstSize, cSrc, cSrcSize);
1766 }
1767 #endif
1768 
1769 #ifndef HUF_FORCE_DECOMPRESS_X1
1770 size_t HUF_readDTableX2(HUF_DTable* DTable, const void* src, size_t srcSize)
1771 {
1772   U32 workSpace[HUF_DECOMPRESS_WORKSPACE_SIZE_U32];
1773   return HUF_readDTableX2_wksp(DTable, src, srcSize,
1774                                workSpace, sizeof(workSpace));
1775 }
1776 
1777 size_t HUF_decompress1X2_DCtx(HUF_DTable* DCtx, void* dst, size_t dstSize,
1778                               const void* cSrc, size_t cSrcSize)
1779 {
1780     U32 workSpace[HUF_DECOMPRESS_WORKSPACE_SIZE_U32];
1781     return HUF_decompress1X2_DCtx_wksp(DCtx, dst, dstSize, cSrc, cSrcSize,
1782                                        workSpace, sizeof(workSpace));
1783 }
1784 
1785 size_t HUF_decompress1X2 (void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize)
1786 {
1787     HUF_CREATE_STATIC_DTABLEX2(DTable, HUF_TABLELOG_MAX);
1788     return HUF_decompress1X2_DCtx(DTable, dst, dstSize, cSrc, cSrcSize);
1789 }
1790 #endif
1791 
1792 #ifndef HUF_FORCE_DECOMPRESS_X2
1793 size_t HUF_decompress4X1_DCtx (HUF_DTable* dctx, void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize)
1794 {
1795     U32 workSpace[HUF_DECOMPRESS_WORKSPACE_SIZE_U32];
1796     return HUF_decompress4X1_DCtx_wksp(dctx, dst, dstSize, cSrc, cSrcSize,
1797                                        workSpace, sizeof(workSpace));
1798 }
1799 size_t HUF_decompress4X1 (void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize)
1800 {
1801     HUF_CREATE_STATIC_DTABLEX1(DTable, HUF_TABLELOG_MAX);
1802     return HUF_decompress4X1_DCtx(DTable, dst, dstSize, cSrc, cSrcSize);
1803 }
1804 #endif
1805 
1806 #ifndef HUF_FORCE_DECOMPRESS_X1
1807 size_t HUF_decompress4X2_DCtx(HUF_DTable* dctx, void* dst, size_t dstSize,
1808                               const void* cSrc, size_t cSrcSize)
1809 {
1810     U32 workSpace[HUF_DECOMPRESS_WORKSPACE_SIZE_U32];
1811     return HUF_decompress4X2_DCtx_wksp(dctx, dst, dstSize, cSrc, cSrcSize,
1812                                        workSpace, sizeof(workSpace));
1813 }
1814 
1815 size_t HUF_decompress4X2 (void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize)
1816 {
1817     HUF_CREATE_STATIC_DTABLEX2(DTable, HUF_TABLELOG_MAX);
1818     return HUF_decompress4X2_DCtx(DTable, dst, dstSize, cSrc, cSrcSize);
1819 }
1820 #endif
1821 
1822 typedef size_t (*decompressionAlgo)(void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize);
1823 
1824 size_t HUF_decompress (void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize)
1825 {
1826 #if !defined(HUF_FORCE_DECOMPRESS_X1) && !defined(HUF_FORCE_DECOMPRESS_X2)
1827     static const decompressionAlgo decompress[2] = { HUF_decompress4X1, HUF_decompress4X2 };
1828 #endif
1829 
1830     /* validation checks */
1831     if (dstSize == 0) return ERROR(dstSize_tooSmall);
1832     if (cSrcSize > dstSize) return ERROR(corruption_detected);   /* invalid */
1833     if (cSrcSize == dstSize) { ZSTD_memcpy(dst, cSrc, dstSize); return dstSize; }   /* not compressed */
1834     if (cSrcSize == 1) { ZSTD_memset(dst, *(const BYTE*)cSrc, dstSize); return dstSize; }   /* RLE */
1835 
1836     {   U32 const algoNb = HUF_selectDecoder(dstSize, cSrcSize);
1837 #if defined(HUF_FORCE_DECOMPRESS_X1)
1838         (void)algoNb;
1839         assert(algoNb == 0);
1840         return HUF_decompress4X1(dst, dstSize, cSrc, cSrcSize);
1841 #elif defined(HUF_FORCE_DECOMPRESS_X2)
1842         (void)algoNb;
1843         assert(algoNb == 1);
1844         return HUF_decompress4X2(dst, dstSize, cSrc, cSrcSize);
1845 #else
1846         return decompress[algoNb](dst, dstSize, cSrc, cSrcSize);
1847 #endif
1848     }
1849 }
1850 
1851 size_t HUF_decompress4X_DCtx (HUF_DTable* dctx, void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize)
1852 {
1853     /* validation checks */
1854     if (dstSize == 0) return ERROR(dstSize_tooSmall);
1855     if (cSrcSize > dstSize) return ERROR(corruption_detected);   /* invalid */
1856     if (cSrcSize == dstSize) { ZSTD_memcpy(dst, cSrc, dstSize); return dstSize; }   /* not compressed */
1857     if (cSrcSize == 1) { ZSTD_memset(dst, *(const BYTE*)cSrc, dstSize); return dstSize; }   /* RLE */
1858 
1859     {   U32 const algoNb = HUF_selectDecoder(dstSize, cSrcSize);
1860 #if defined(HUF_FORCE_DECOMPRESS_X1)
1861         (void)algoNb;
1862         assert(algoNb == 0);
1863         return HUF_decompress4X1_DCtx(dctx, dst, dstSize, cSrc, cSrcSize);
1864 #elif defined(HUF_FORCE_DECOMPRESS_X2)
1865         (void)algoNb;
1866         assert(algoNb == 1);
1867         return HUF_decompress4X2_DCtx(dctx, dst, dstSize, cSrc, cSrcSize);
1868 #else
1869         return algoNb ? HUF_decompress4X2_DCtx(dctx, dst, dstSize, cSrc, cSrcSize) :
1870                         HUF_decompress4X1_DCtx(dctx, dst, dstSize, cSrc, cSrcSize) ;
1871 #endif
1872     }
1873 }
1874 
1875 size_t HUF_decompress4X_hufOnly(HUF_DTable* dctx, void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize)
1876 {
1877     U32 workSpace[HUF_DECOMPRESS_WORKSPACE_SIZE_U32];
1878     return HUF_decompress4X_hufOnly_wksp(dctx, dst, dstSize, cSrc, cSrcSize,
1879                                          workSpace, sizeof(workSpace));
1880 }
1881 
1882 size_t HUF_decompress1X_DCtx(HUF_DTable* dctx, void* dst, size_t dstSize,
1883                              const void* cSrc, size_t cSrcSize)
1884 {
1885     U32 workSpace[HUF_DECOMPRESS_WORKSPACE_SIZE_U32];
1886     return HUF_decompress1X_DCtx_wksp(dctx, dst, dstSize, cSrc, cSrcSize,
1887                                       workSpace, sizeof(workSpace));
1888 }
1889 #endif
1890