/src/zstd/lib/common/fse_decompress.c

Source
/* ******************************************************************
 * FSE : Finite State Entropy decoder
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 *  You can contact the author at :
 *  - FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy
 *  - Public forum : https://groups.google.com/forum/#!forum/lz4c
 *
 * This source code is licensed under both the BSD-style license (found in the
 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
 * in the COPYING file in the root directory of this source tree).
 * You may select, at your option, one of the above-listed licenses.
****************************************************************** */


/* **************************************************************
*  Includes
****************************************************************/
#include "debug.h"      /* assert */
#include "bitstream.h"
#include "bmi2.h"
#include "compiler.h"
#define FSE_STATIC_LINKING_ONLY
#include "fse.h"
#include "error_private.h"
#include "zstd_deps.h"  /* ZSTD_memcpy */
#include "bits.h"       /* ZSTD_highbit32 */


/* **************************************************************
*  Error Management
****************************************************************/
#define FSE_isError ERR_isError
#define FSE_STATIC_ASSERT(c) DEBUG_STATIC_ASSERT(c)   /* use only *after* variable declarations */


/* **************************************************************
*  Templates
****************************************************************/
/*
  designed to be included
  for type-specific functions (template emulation in C)
  Objective is to write these functions only once, for improved maintenance
*/

/* safety checks */
#ifndef FSE_FUNCTION_EXTENSION
#  error "FSE_FUNCTION_EXTENSION must be defined"
#endif
#ifndef FSE_FUNCTION_TYPE
#  error "FSE_FUNCTION_TYPE must be defined"
#endif

/* Function names */
#define FSE_CAT(X,Y) X##Y
#define FSE_FUNCTION_NAME(X,Y) FSE_CAT(X,Y)
#define FSE_TYPE_NAME(X,Y) FSE_CAT(X,Y)

static size_t FSE_buildDTable_internal(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize)
{
    void* const tdPtr = dt+1;   /* because *dt is unsigned, 32-bits aligned on 32-bits */
    FSE_DECODE_TYPE* const tableDecode = (FSE_DECODE_TYPE*) (tdPtr);
    U16* symbolNext = (U16*)workSpace;
    BYTE* spread = (BYTE*)(symbolNext + maxSymbolValue + 1);

    U32 const maxSV1 = maxSymbolValue + 1;
    U32 const tableSize = 1 << tableLog;
    U32 highThreshold = tableSize-1;

    /* Sanity Checks */
    if (FSE_BUILD_DTABLE_WKSP_SIZE(tableLog, maxSymbolValue) > wkspSize) return ERROR(maxSymbolValue_tooLarge);
    if (maxSymbolValue > FSE_MAX_SYMBOL_VALUE) return ERROR(maxSymbolValue_tooLarge);
    if (tableLog > FSE_MAX_TABLELOG) return ERROR(tableLog_tooLarge);

    /* Init, lay down lowprob symbols */
    {   FSE_DTableHeader DTableH;
        DTableH.tableLog = (U16)tableLog;
        DTableH.fastMode = 1;
        {   S16 const largeLimit= (S16)(1 << (tableLog-1));
            U32 s;
            for (s=0; s<maxSV1; s++) {
                if (normalizedCounter[s]==-1) {
                    tableDecode[highThreshold--].symbol = (FSE_FUNCTION_TYPE)s;
                    symbolNext[s] = 1;
                } else {
                    if (normalizedCounter[s] >= largeLimit) DTableH.fastMode=0;
                    symbolNext[s] = (U16)normalizedCounter[s];
        }   }   }
        ZSTD_memcpy(dt, &DTableH, sizeof(DTableH));
    }

    /* Spread symbols */
    if (highThreshold == tableSize - 1) {
        size_t const tableMask = tableSize-1;
        size_t const step = FSE_TABLESTEP(tableSize);
        /* First lay down the symbols in order.
         * We use a uint64_t to lay down 8 bytes at a time. This reduces branch
         * misses since small blocks generally have small table logs, so nearly
         * all symbols have counts <= 8. We ensure we have 8 bytes at the end of
         * our buffer to handle the over-write.
         */
        {   U64 const add = 0x0101010101010101ull;
            size_t pos = 0;
            U64 sv = 0;
            U32 s;
            for (s=0; s<maxSV1; ++s, sv += add) {
                int i;
                int const n = normalizedCounter[s];
                MEM_write64(spread + pos, sv);
                for (i = 8; i < n; i += 8) {
                    MEM_write64(spread + pos + i, sv);
                }
                pos += (size_t)n;
        }   }
        /* Now we spread those positions across the table.
         * The benefit of doing it in two stages is that we avoid the
         * variable size inner loop, which caused lots of branch misses.
         * Now we can run through all the positions without any branch misses.
         * We unroll the loop twice, since that is what empirically worked best.
         */
        {
            size_t position = 0;
            size_t s;
            size_t const unroll = 2;
            assert(tableSize % unroll == 0); /* FSE_MIN_TABLELOG is 5 */
            for (s = 0; s < (size_t)tableSize; s += unroll) {
                size_t u;
                for (u = 0; u < unroll; ++u) {
                    size_t const uPosition = (position + (u * step)) & tableMask;
                    tableDecode[uPosition].symbol = spread[s + u];
                }
                position = (position + (unroll * step)) & tableMask;
            }
            assert(position == 0);
        }
    } else {
        U32 const tableMask = tableSize-1;
        U32 const step = FSE_TABLESTEP(tableSize);
        U32 s, position = 0;
        for (s=0; s<maxSV1; s++) {
            int i;
            for (i=0; i<normalizedCounter[s]; i++) {
                tableDecode[position].symbol = (FSE_FUNCTION_TYPE)s;
                position = (position + step) & tableMask;
                while (position > highThreshold) position = (position + step) & tableMask;   /* lowprob area */
        }   }
        if (position!=0) return ERROR(GENERIC);   /* position must reach all cells once, otherwise normalizedCounter is incorrect */
    }

    /* Build Decoding table */
    {   U32 u;
        for (u=0; u<tableSize; u++) {
            FSE_FUNCTION_TYPE const symbol = (FSE_FUNCTION_TYPE)(tableDecode[u].symbol);
            U32 const nextState = symbolNext[symbol]++;
            tableDecode[u].nbBits = (BYTE) (tableLog - ZSTD_highbit32(nextState) );
            tableDecode[u].newState = (U16) ( (nextState << tableDecode[u].nbBits) - tableSize);
    }   }

    return 0;
}

size_t FSE_buildDTable_wksp(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize)
{
    return FSE_buildDTable_internal(dt, normalizedCounter, maxSymbolValue, tableLog, workSpace, wkspSize);
}


#ifndef FSE_COMMONDEFS_ONLY

/*-*******************************************************
*  Decompression (Byte symbols)
*********************************************************/

FORCE_INLINE_TEMPLATE size_t FSE_decompress_usingDTable_generic(
          void* dst, size_t maxDstSize,
    const void* cSrc, size_t cSrcSize,
    const FSE_DTable* dt, const unsigned fast)
{
    BYTE* const ostart = (BYTE*) dst;
    BYTE* op = ostart;
    BYTE* const omax = op + maxDstSize;
    BYTE* const olimit = omax-3;

    BIT_DStream_t bitD;
    FSE_DState_t state1;
    FSE_DState_t state2;

    /* Init */
    CHECK_F(BIT_initDStream(&bitD, cSrc, cSrcSize));

    FSE_initDState(&state1, &bitD, dt);
    FSE_initDState(&state2, &bitD, dt);

    RETURN_ERROR_IF(BIT_reloadDStream(&bitD)==BIT_DStream_overflow, corruption_detected, "");

#define FSE_GETSYMBOL(statePtr) fast ? FSE_decodeSymbolFast(statePtr, &bitD) : FSE_decodeSymbol(statePtr, &bitD)

    /* 4 symbols per loop */
    for ( ; (BIT_reloadDStream(&bitD)==BIT_DStream_unfinished) & (op<olimit) ; op+=4) {
        op[0] = FSE_GETSYMBOL(&state1);

        if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
            BIT_reloadDStream(&bitD);

        op[1] = FSE_GETSYMBOL(&state2);

        if (FSE_MAX_TABLELOG*4+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
            { if (BIT_reloadDStream(&bitD) > BIT_DStream_unfinished) { op+=2; break; } }

        op[2] = FSE_GETSYMBOL(&state1);

        if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
            BIT_reloadDStream(&bitD);

        op[3] = FSE_GETSYMBOL(&state2);
    }

    /* tail */
    /* note : BIT_reloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly BIT_DStream_completed */
    while (1) {
        if (op>(omax-2)) return ERROR(dstSize_tooSmall);
        *op++ = FSE_GETSYMBOL(&state1);
        if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) {
            *op++ = FSE_GETSYMBOL(&state2);
            break;
        }

        if (op>(omax-2)) return ERROR(dstSize_tooSmall);
        *op++ = FSE_GETSYMBOL(&state2);
        if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) {
            *op++ = FSE_GETSYMBOL(&state1);
            break;
    }   }

    assert(op >= ostart);
    return (size_t)(op-ostart);
}

typedef struct {
    short ncount[FSE_MAX_SYMBOL_VALUE + 1];
} FSE_DecompressWksp;


FORCE_INLINE_TEMPLATE size_t FSE_decompress_wksp_body(
        void* dst, size_t dstCapacity,
        const void* cSrc, size_t cSrcSize,
        unsigned maxLog, void* workSpace, size_t wkspSize,
        int bmi2)
{
    const BYTE* const istart = (const BYTE*)cSrc;
    const BYTE* ip = istart;
    unsigned tableLog;
    unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;
    FSE_DecompressWksp* const wksp = (FSE_DecompressWksp*)workSpace;
    size_t const dtablePos = sizeof(FSE_DecompressWksp) / sizeof(FSE_DTable);
    FSE_DTable* const dtable = (FSE_DTable*)workSpace + dtablePos;

    FSE_STATIC_ASSERT((FSE_MAX_SYMBOL_VALUE + 1) % 2 == 0);
    if (wkspSize < sizeof(*wksp)) return ERROR(GENERIC);

    /* correct offset to dtable depends on this property */
    FSE_STATIC_ASSERT(sizeof(FSE_DecompressWksp) % sizeof(FSE_DTable) == 0);

    /* normal FSE decoding mode */
    {   size_t const NCountLength =
            FSE_readNCount_bmi2(wksp->ncount, &maxSymbolValue, &tableLog, istart, cSrcSize, bmi2);
        if (FSE_isError(NCountLength)) return NCountLength;
        if (tableLog > maxLog) return ERROR(tableLog_tooLarge);
        assert(NCountLength <= cSrcSize);
        ip += NCountLength;
        cSrcSize -= NCountLength;
    }

    if (FSE_DECOMPRESS_WKSP_SIZE(tableLog, maxSymbolValue) > wkspSize) return ERROR(tableLog_tooLarge);
    assert(sizeof(*wksp) + FSE_DTABLE_SIZE(tableLog) <= wkspSize);
    workSpace = (BYTE*)workSpace + sizeof(*wksp) + FSE_DTABLE_SIZE(tableLog);
    wkspSize -= sizeof(*wksp) + FSE_DTABLE_SIZE(tableLog);

    CHECK_F( FSE_buildDTable_internal(dtable, wksp->ncount, maxSymbolValue, tableLog, workSpace, wkspSize) );

    {
        const void* ptr = dtable;
        const FSE_DTableHeader* DTableH = (const FSE_DTableHeader*)ptr;
        const U32 fastMode = DTableH->fastMode;

        /* select fast mode (static) */
        if (fastMode) return FSE_decompress_usingDTable_generic(dst, dstCapacity, ip, cSrcSize, dtable, 1);
        return FSE_decompress_usingDTable_generic(dst, dstCapacity, ip, cSrcSize, dtable, 0);
    }
}

/* Avoids the FORCE_INLINE of the _body() function. */
static size_t FSE_decompress_wksp_body_default(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize)
{
    return FSE_decompress_wksp_body(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, 0);
}

#if DYNAMIC_BMI2
BMI2_TARGET_ATTRIBUTE static size_t FSE_decompress_wksp_body_bmi2(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize)
{
    return FSE_decompress_wksp_body(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, 1);
}
#else
#define FSE_decompress_wksp_body_bmi2 FSE_decompress_wksp_body_default
#endif

size_t FSE_decompress_wksp_bmi2(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize, int bmi2)
{
    if (ZSTD_USE_BMI2(bmi2)) {
        return FSE_decompress_wksp_body_bmi2(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize);
    }
    (void)bmi2;
    return FSE_decompress_wksp_body_default(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize);
}

#endif   /* FSE_COMMONDEFS_ONLY */

Coverage Report

Created: 2026-10-28 07:26

Line	Count	Source
1		/* ******************************************************************
2		* FSE : Finite State Entropy decoder
3		* Copyright (c) Meta Platforms, Inc. and affiliates.
4		*
5		* You can contact the author at :
6		* - FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy
7		* - Public forum : https://groups.google.com/forum/#!forum/lz4c
8		*
9		* This source code is licensed under both the BSD-style license (found in the
10		* LICENSE file in the root directory of this source tree) and the GPLv2 (found
11		* in the COPYING file in the root directory of this source tree).
12		* You may select, at your option, one of the above-listed licenses.
13		****************************************************************** */
14
15
16		/* **************************************************************
17		* Includes
18		****************************************************************/
19		#include "debug.h" /* assert */
20		#include "bitstream.h"
21		#include "bmi2.h"
22		#include "compiler.h"
23		#define FSE_STATIC_LINKING_ONLY
24		#include "fse.h"
25		#include "error_private.h"
26		#include "zstd_deps.h" /* ZSTD_memcpy */
27		#include "bits.h" /* ZSTD_highbit32 */
28
29
30		/* **************************************************************
31		* Error Management
32		****************************************************************/
33	1.18k	#define FSE_isError ERR_isError
34	2.36k	#define FSE_STATIC_ASSERT(c) DEBUG_STATIC_ASSERT(c) /* use only after variable declarations */
35
36
37		/* **************************************************************
38		* Templates
39		****************************************************************/
40		/*
41		designed to be included
42		for type-specific functions (template emulation in C)
43		Objective is to write these functions only once, for improved maintenance
44		*/
45
46		/* safety checks */
47		#ifndef FSE_FUNCTION_EXTENSION
48		# error "FSE_FUNCTION_EXTENSION must be defined"
49		#endif
50		#ifndef FSE_FUNCTION_TYPE
51		# error "FSE_FUNCTION_TYPE must be defined"
52		#endif
53
54		/* Function names */
55		#define FSE_CAT(X,Y) X##Y
56		#define FSE_FUNCTION_NAME(X,Y) FSE_CAT(X,Y)
57		#define FSE_TYPE_NAME(X,Y) FSE_CAT(X,Y)
58
59		static size_t FSE_buildDTable_internal(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize)
60	1.07k	{
61	1.07k	void* const tdPtr = dt+1; /* because dt is unsigned, 32-bits aligned on 32-bits /
62	1.07k	FSE_DECODE_TYPE* const tableDecode = (FSE_DECODE_TYPE*) (tdPtr);
63	1.07k	U16* symbolNext = (U16*)workSpace;
64	1.07k	BYTE* spread = (BYTE*)(symbolNext + maxSymbolValue + 1);
65
66	1.07k	U32 const maxSV1 = maxSymbolValue + 1;
67	1.07k	U32 const tableSize = 1 << tableLog;
68	1.07k	U32 highThreshold = tableSize-1;
69
70		/* Sanity Checks */
71	1.07k	if (FSE_BUILD_DTABLE_WKSP_SIZE(tableLog, maxSymbolValue) > wkspSize) return ERROR(maxSymbolValue_tooLarge);
72	1.07k	if (maxSymbolValue > FSE_MAX_SYMBOL_VALUE) return ERROR(maxSymbolValue_tooLarge);
73	1.07k	if (tableLog > FSE_MAX_TABLELOG) return ERROR(tableLog_tooLarge);
74
75		/* Init, lay down lowprob symbols */
76	1.07k	{ FSE_DTableHeader DTableH;
77	1.07k	DTableH.tableLog = (U16)tableLog;
78	1.07k	DTableH.fastMode = 1;
79	1.07k	{ S16 const largeLimit= (S16)(1 << (tableLog-1));
80	1.07k	U32 s;
81	11.2k	for (s=0; s<maxSV1; s++) {
82	10.1k	if (normalizedCounter[s]==-1) {
83	5.60k	tableDecode[highThreshold--].symbol = (FSE_FUNCTION_TYPE)s;
84	5.60k	symbolNext[s] = 1;
85	5.60k	} else {
86	4.54k	if (normalizedCounter[s] >= largeLimit) DTableH.fastMode=0;
87	4.54k	symbolNext[s] = (U16)normalizedCounter[s];
88	4.54k	} } }
89	1.07k	ZSTD_memcpy(dt, &DTableH, sizeof(DTableH));
90	1.07k	}
91
92		/* Spread symbols */
93	1.07k	if (highThreshold == tableSize - 1) {
94	110	size_t const tableMask = tableSize-1;
95	110	size_t const step = FSE_TABLESTEP(tableSize);
96		/* First lay down the symbols in order.
97		* We use a uint64_t to lay down 8 bytes at a time. This reduces branch
98		* misses since small blocks generally have small table logs, so nearly
99		* all symbols have counts <= 8. We ensure we have 8 bytes at the end of
100		* our buffer to handle the over-write.
101		*/
102	110	{ U64 const add = 0x0101010101010101ull;
103	110	size_t pos = 0;
104	110	U64 sv = 0;
105	110	U32 s;
106	734	for (s=0; s<maxSV1; ++s, sv += add) {
107	624	int i;
108	624	int const n = normalizedCounter[s];
109	624	MEM_write64(spread + pos, sv);
110	1.00k	for (i = 8; i < n; i += 8) {
111	381	MEM_write64(spread + pos + i, sv);
112	381	}
113	624	pos += (size_t)n;
114	624	} }
115		/* Now we spread those positions across the table.
116		* The benefit of doing it in two stages is that we avoid the
117		* variable size inner loop, which caused lots of branch misses.
118		* Now we can run through all the positions without any branch misses.
119		* We unroll the loop twice, since that is what empirically worked best.
120		*/
121	110	{
122	110	size_t position = 0;
123	110	size_t s;
124	110	size_t const unroll = 2;
125	110	assert(tableSize % unroll == 0); /* FSE_MIN_TABLELOG is 5 */
126	2.23k	for (s = 0; s < (size_t)tableSize; s += unroll) {
127	2.12k	size_t u;
128	6.38k	for (u = 0; u < unroll; ++u) {
129	4.25k	size_t const uPosition = (position + (u * step)) & tableMask;
130	4.25k	tableDecode[uPosition].symbol = spread[s + u];
131	4.25k	}
132	2.12k	position = (position + (unroll * step)) & tableMask;
133	2.12k	}
134	110	assert(position == 0);
135	110	}
136	964	} else {
137	964	U32 const tableMask = tableSize-1;
138	964	U32 const step = FSE_TABLESTEP(tableSize);
139	964	U32 s, position = 0;
140	10.4k	for (s=0; s<maxSV1; s++) {
141	9.51k	int i;
142	39.6k	for (i=0; i<normalizedCounter[s]; i++) {
143	30.1k	tableDecode[position].symbol = (FSE_FUNCTION_TYPE)s;
144	30.1k	position = (position + step) & tableMask;
145	35.5k	while (position > highThreshold) position = (position + step) & tableMask; /* lowprob area */
146	30.1k	} }
147	964	if (position!=0) return ERROR(GENERIC); /* position must reach all cells once, otherwise normalizedCounter is incorrect */
148	964	}
149
150		/* Build Decoding table */
151	1.07k	{ U32 u;
152	41.0k	for (u=0; u<tableSize; u++) {
153	39.9k	FSE_FUNCTION_TYPE const symbol = (FSE_FUNCTION_TYPE)(tableDecode[u].symbol);
154	39.9k	U32 const nextState = symbolNext[symbol]++;
155	39.9k	tableDecode[u].nbBits = (BYTE) (tableLog - ZSTD_highbit32(nextState) );
156	39.9k	tableDecode[u].newState = (U16) ( (nextState << tableDecode[u].nbBits) - tableSize);
157	39.9k	} }
158
159	1.07k	return 0;
160	1.07k	}
161
162		size_t FSE_buildDTable_wksp(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize)
163	0	{
164	0	return FSE_buildDTable_internal(dt, normalizedCounter, maxSymbolValue, tableLog, workSpace, wkspSize);
165	0	}
166
167
168		#ifndef FSE_COMMONDEFS_ONLY
169
170		/-******************************************************
171		* Decompression (Byte symbols)
172		*********************************************************/
173
174		FORCE_INLINE_TEMPLATE size_t FSE_decompress_usingDTable_generic(
175		void* dst, size_t maxDstSize,
176		const void* cSrc, size_t cSrcSize,
177		const FSE_DTable* dt, const unsigned fast)
178	1.07k	{
179	1.07k	BYTE* const ostart = (BYTE*) dst;
180	1.07k	BYTE* op = ostart;
181	1.07k	BYTE* const omax = op + maxDstSize;
182	1.07k	BYTE* const olimit = omax-3;
183
184	1.07k	BIT_DStream_t bitD;
185	1.07k	FSE_DState_t state1;
186	1.07k	FSE_DState_t state2;
187
188		/* Init */
189	1.07k	CHECK_F(BIT_initDStream(&bitD, cSrc, cSrcSize));
190
191	1.04k	FSE_initDState(&state1, &bitD, dt);
192	1.04k	FSE_initDState(&state2, &bitD, dt);
193
194	1.04k	RETURN_ERROR_IF(BIT_reloadDStream(&bitD)==BIT_DStream_overflow, corruption_detected, "");
195
196	158k	#define FSE_GETSYMBOL(statePtr) fast ? FSE_decodeSymbolFast(statePtr, &bitD) : FSE_decodeSymbol(statePtr, &bitD)
197
198		/* 4 symbols per loop */
199	28.0k	for ( ; (BIT_reloadDStream(&bitD)==BIT_DStream_unfinished) & (op<olimit) ; op+=4) {
200	27.0k	op[0] = FSE_GETSYMBOL(&state1);
201
202	27.0k	if (FSE_MAX_TABLELOG2+7 > sizeof(bitD.bitContainer)8) /* This test must be static */
203	0	BIT_reloadDStream(&bitD);
204
205	27.0k	op[1] = FSE_GETSYMBOL(&state2);
206
207	27.0k	if (FSE_MAX_TABLELOG4+7 > sizeof(bitD.bitContainer)8) /* This test must be static */
208	0	{ if (BIT_reloadDStream(&bitD) > BIT_DStream_unfinished) { op+=2; break; } }
209
210	27.0k	op[2] = FSE_GETSYMBOL(&state1);
211
212	27.0k	if (FSE_MAX_TABLELOG2+7 > sizeof(bitD.bitContainer)8) /* This test must be static */
213	0	BIT_reloadDStream(&bitD);
214
215	27.0k	op[3] = FSE_GETSYMBOL(&state2);
216	27.0k	}
217
218		/* tail */
219		/* note : BIT_reloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly BIT_DStream_completed */
220	24.6k	while (1) {
221	24.6k	if (op>(omax-2)) return ERROR(dstSize_tooSmall);
222	24.6k	*op++ = FSE_GETSYMBOL(&state1);
223	24.6k	if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) {
224	331	*op++ = FSE_GETSYMBOL(&state2);
225	331	break;
226	331	}
227
228	24.3k	if (op>(omax-2)) return ERROR(dstSize_tooSmall);
229	24.3k	*op++ = FSE_GETSYMBOL(&state2);
230	24.3k	if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) {
231	683	*op++ = FSE_GETSYMBOL(&state1);
232	683	break;
233	683	} }
234
235	1.01k	assert(op >= ostart);
236	1.01k	return (size_t)(op-ostart);
237	1.03k	}
238
239		typedef struct {
240		short ncount[FSE_MAX_SYMBOL_VALUE + 1];
241		} FSE_DecompressWksp;
242
243
244		FORCE_INLINE_TEMPLATE size_t FSE_decompress_wksp_body(
245		void* dst, size_t dstCapacity,
246		const void* cSrc, size_t cSrcSize,
247		unsigned maxLog, void* workSpace, size_t wkspSize,
248		int bmi2)
249	1.18k	{
250	1.18k	const BYTE* const istart = (const BYTE*)cSrc;
251	1.18k	const BYTE* ip = istart;
252	1.18k	unsigned tableLog;
253	1.18k	unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;
254	1.18k	FSE_DecompressWksp* const wksp = (FSE_DecompressWksp*)workSpace;
255	1.18k	size_t const dtablePos = sizeof(FSE_DecompressWksp) / sizeof(FSE_DTable);
256	1.18k	FSE_DTable* const dtable = (FSE_DTable*)workSpace + dtablePos;
257
258	1.18k	FSE_STATIC_ASSERT((FSE_MAX_SYMBOL_VALUE + 1) % 2 == 0);
259	1.18k	if (wkspSize < sizeof(*wksp)) return ERROR(GENERIC);
260
261		/* correct offset to dtable depends on this property */
262	1.18k	FSE_STATIC_ASSERT(sizeof(FSE_DecompressWksp) % sizeof(FSE_DTable) == 0);
263
264		/* normal FSE decoding mode */
265	1.18k	{ size_t const NCountLength =
266	1.18k	FSE_readNCount_bmi2(wksp->ncount, &maxSymbolValue, &tableLog, istart, cSrcSize, bmi2);
267	1.18k	if (FSE_isError(NCountLength)) return NCountLength;
268	1.13k	if (tableLog > maxLog) return ERROR(tableLog_tooLarge);
269	1.08k	assert(NCountLength <= cSrcSize);
270	1.08k	ip += NCountLength;
271	1.08k	cSrcSize -= NCountLength;
272	1.08k	}
273
274	1.08k	if (FSE_DECOMPRESS_WKSP_SIZE(tableLog, maxSymbolValue) > wkspSize) return ERROR(tableLog_tooLarge);
275	1.07k	assert(sizeof(*wksp) + FSE_DTABLE_SIZE(tableLog) <= wkspSize);
276	1.07k	workSpace = (BYTE)workSpace + sizeof(wksp) + FSE_DTABLE_SIZE(tableLog);
277	1.07k	wkspSize -= sizeof(*wksp) + FSE_DTABLE_SIZE(tableLog);
278
279	1.07k	CHECK_F( FSE_buildDTable_internal(dtable, wksp->ncount, maxSymbolValue, tableLog, workSpace, wkspSize) );
280
281	1.07k	{
282	1.07k	const void* ptr = dtable;
283	1.07k	const FSE_DTableHeader* DTableH = (const FSE_DTableHeader*)ptr;
284	1.07k	const U32 fastMode = DTableH->fastMode;
285
286		/* select fast mode (static) */
287	1.07k	if (fastMode) return FSE_decompress_usingDTable_generic(dst, dstCapacity, ip, cSrcSize, dtable, 1);
288	915	return FSE_decompress_usingDTable_generic(dst, dstCapacity, ip, cSrcSize, dtable, 0);
289	1.07k	}
290	1.07k	}
291
292		/* Avoids the FORCE_INLINE of the _body() function. */
293		static size_t FSE_decompress_wksp_body_default(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize)
294	0	{
295	0	return FSE_decompress_wksp_body(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, 0);
296	0	}
297
298		#if DYNAMIC_BMI2
299		BMI2_TARGET_ATTRIBUTE static size_t FSE_decompress_wksp_body_bmi2(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize)
300	1.18k	{
301	1.18k	return FSE_decompress_wksp_body(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, 1);
302	1.18k	}
303		#else
304		#define FSE_decompress_wksp_body_bmi2 FSE_decompress_wksp_body_default
305		#endif
306
307		size_t FSE_decompress_wksp_bmi2(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize, int bmi2)
308	1.18k	{
309	1.18k	if (ZSTD_USE_BMI2(bmi2)) {
310	1.18k	return FSE_decompress_wksp_body_bmi2(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize);
311	1.18k	}
312	0	(void)bmi2;
313	0	return FSE_decompress_wksp_body_default(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize);
314	1.18k	}
315
316		#endif /* FSE_COMMONDEFS_ONLY */