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/*-***************************/
132typedef struct { BYTE maxTableLog; BYTE tableType; BYTE tableLog; BYTE reserved; } DTableDesc;
133
134static 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
143static 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}
150typedef 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 */
166static 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
251static 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/*-***************************/
281typedef 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 */
287static 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 */
303static 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
328typedef 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
337size_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
342size_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
480FORCE_INLINE_TEMPLATE BYTE
481HUF_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
500HINT_INLINE size_t
501HUF_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
529FORCE_INLINE_TEMPLATE size_t
530HUF_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
552FORCE_INLINE_TEMPLATE size_t
553HUF_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
650static BMI2_TARGET_ATTRIBUTE
651size_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
658static
659size_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
667HUF_ASM_DECL void HUF_decompress4X1_usingDTable_internal_bmi2_asm_loop(HUF_DecompressAsmArgs* args) ZSTDLIB_HIDDEN;
668
669static HUF_ASM_X86_64_BMI2_ATTRS
670size_t
671HUF_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
723typedef 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
728HUF_DGEN(HUF_decompress1X1_usingDTable_internal)
729
730static 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
753size_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
763size_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
778size_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
788static 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
802size_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
819typedef struct { U16 sequence; BYTE nbBits; BYTE length; } HUF_DEltX2;  /* double-symbols decoding */
820typedef struct { BYTE symbol; } sortedSymbol_t;
821typedef U32 rankValCol_t[HUF_TABLELOG_MAX + 1];
822typedef rankValCol_t rankVal_t[HUF_TABLELOG_MAX];
823
824/**
825 * Constructs a HUF_DEltX2 in a U32.
826 */
827static 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 */
846static 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 */
858static 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 */
876static 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 */
935static 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
990static 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
1036typedef 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
1045size_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
1052size_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
1138FORCE_INLINE_TEMPLATE U32
1139HUF_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
1147FORCE_INLINE_TEMPLATE U32
1148HUF_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
1176HINT_INLINE size_t
1177HUF_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
1221FORCE_INLINE_TEMPLATE size_t
1222HUF_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}
1247FORCE_INLINE_TEMPLATE size_t
1248HUF_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
1366static BMI2_TARGET_ATTRIBUTE
1367size_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
1374static
1375size_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
1383HUF_ASM_DECL void HUF_decompress4X2_usingDTable_internal_bmi2_asm_loop(HUF_DecompressAsmArgs* args) ZSTDLIB_HIDDEN;
1384
1385static HUF_ASM_X86_64_BMI2_ATTRS size_t
1386HUF_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
1435static 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
1457HUF_DGEN(HUF_decompress1X2_usingDTable_internal)
1458
1459size_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
1469size_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
1485size_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
1495static 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
1510size_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
1525size_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
1544size_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)
1565typedef struct { U32 tableTime; U32 decode256Time; } algo_time_t;
1566static 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 */
1593U32 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
1618size_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
1644size_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
1675size_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
1693size_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
1706size_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
1723size_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
1747size_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
1754size_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
1762size_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
1770size_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
1777size_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
1785size_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
1793size_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}
1799size_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
1807size_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
1815size_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
1822typedef size_t (*decompressionAlgo)(void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize);
1823
1824size_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
1851size_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
1875size_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
1882size_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