1/* ******************************************************************
2 * FSE : Finite State Entropy decoder
3 * Copyright (c) Yann Collet, Facebook, Inc.
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 "compiler.h"
22#define FSE_STATIC_LINKING_ONLY
23#include "fse.h"
24#include "error_private.h"
25#define ZSTD_DEPS_NEED_MALLOC
26#include "zstd_deps.h"
27
28
29/* **************************************************************
30*  Error Management
31****************************************************************/
32#define FSE_isError ERR_isError
33#define FSE_STATIC_ASSERT(c) DEBUG_STATIC_ASSERT(c)   /* use only *after* variable declarations */
34
35
36/* **************************************************************
37*  Templates
38****************************************************************/
39/*
40  designed to be included
41  for type-specific functions (template emulation in C)
42  Objective is to write these functions only once, for improved maintenance
43*/
44
45/* safety checks */
46#ifndef FSE_FUNCTION_EXTENSION
47#  error "FSE_FUNCTION_EXTENSION must be defined"
48#endif
49#ifndef FSE_FUNCTION_TYPE
50#  error "FSE_FUNCTION_TYPE must be defined"
51#endif
52
53/* Function names */
54#define FSE_CAT(X,Y) X##Y
55#define FSE_FUNCTION_NAME(X,Y) FSE_CAT(X,Y)
56#define FSE_TYPE_NAME(X,Y) FSE_CAT(X,Y)
57
58
59/* Function templates */
60FSE_DTable* FSE_createDTable (unsigned tableLog)
61{
62    if (tableLog > FSE_TABLELOG_ABSOLUTE_MAX) tableLog = FSE_TABLELOG_ABSOLUTE_MAX;
63    return (FSE_DTable*)ZSTD_malloc( FSE_DTABLE_SIZE_U32(tableLog) * sizeof (U32) );
64}
65
66void FSE_freeDTable (FSE_DTable* dt)
67{
68    ZSTD_free(dt);
69}
70
71static size_t FSE_buildDTable_internal(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize)
72{
73    void* const tdPtr = dt+1;   /* because *dt is unsigned, 32-bits aligned on 32-bits */
74    FSE_DECODE_TYPE* const tableDecode = (FSE_DECODE_TYPE*) (tdPtr);
75    U16* symbolNext = (U16*)workSpace;
76    BYTE* spread = (BYTE*)(symbolNext + maxSymbolValue + 1);
77
78    U32 const maxSV1 = maxSymbolValue + 1;
79    U32 const tableSize = 1 << tableLog;
80    U32 highThreshold = tableSize-1;
81
82    /* Sanity Checks */
83    if (FSE_BUILD_DTABLE_WKSP_SIZE(tableLog, maxSymbolValue) > wkspSize) return ERROR(maxSymbolValue_tooLarge);
84    if (maxSymbolValue > FSE_MAX_SYMBOL_VALUE) return ERROR(maxSymbolValue_tooLarge);
85    if (tableLog > FSE_MAX_TABLELOG) return ERROR(tableLog_tooLarge);
86
87    /* Init, lay down lowprob symbols */
88    {   FSE_DTableHeader DTableH;
89        DTableH.tableLog = (U16)tableLog;
90        DTableH.fastMode = 1;
91        {   S16 const largeLimit= (S16)(1 << (tableLog-1));
92            U32 s;
93            for (s=0; s<maxSV1; s++) {
94                if (normalizedCounter[s]==-1) {
95                    tableDecode[highThreshold--].symbol = (FSE_FUNCTION_TYPE)s;
96                    symbolNext[s] = 1;
97                } else {
98                    if (normalizedCounter[s] >= largeLimit) DTableH.fastMode=0;
99                    symbolNext[s] = normalizedCounter[s];
100        }   }   }
101        ZSTD_memcpy(dt, &DTableH, sizeof(DTableH));
102    }
103
104    /* Spread symbols */
105    if (highThreshold == tableSize - 1) {
106        size_t const tableMask = tableSize-1;
107        size_t const step = FSE_TABLESTEP(tableSize);
108        /* First lay down the symbols in order.
109         * We use a uint64_t to lay down 8 bytes at a time. This reduces branch
110         * misses since small blocks generally have small table logs, so nearly
111         * all symbols have counts <= 8. We ensure we have 8 bytes at the end of
112         * our buffer to handle the over-write.
113         */
114        {
115            U64 const add = 0x0101010101010101ull;
116            size_t pos = 0;
117            U64 sv = 0;
118            U32 s;
119            for (s=0; s<maxSV1; ++s, sv += add) {
120                int i;
121                int const n = normalizedCounter[s];
122                MEM_write64(spread + pos, sv);
123                for (i = 8; i < n; i += 8) {
124                    MEM_write64(spread + pos + i, sv);
125                }
126                pos += n;
127            }
128        }
129        /* Now we spread those positions across the table.
130         * The benefit of doing it in two stages is that we avoid the the
131         * variable size inner loop, which caused lots of branch misses.
132         * Now we can run through all the positions without any branch misses.
133         * We unroll the loop twice, since that is what emperically worked best.
134         */
135        {
136            size_t position = 0;
137            size_t s;
138            size_t const unroll = 2;
139            assert(tableSize % unroll == 0); /* FSE_MIN_TABLELOG is 5 */
140            for (s = 0; s < (size_t)tableSize; s += unroll) {
141                size_t u;
142                for (u = 0; u < unroll; ++u) {
143                    size_t const uPosition = (position + (u * step)) & tableMask;
144                    tableDecode[uPosition].symbol = spread[s + u];
145                }
146                position = (position + (unroll * step)) & tableMask;
147            }
148            assert(position == 0);
149        }
150    } else {
151        U32 const tableMask = tableSize-1;
152        U32 const step = FSE_TABLESTEP(tableSize);
153        U32 s, position = 0;
154        for (s=0; s<maxSV1; s++) {
155            int i;
156            for (i=0; i<normalizedCounter[s]; i++) {
157                tableDecode[position].symbol = (FSE_FUNCTION_TYPE)s;
158                position = (position + step) & tableMask;
159                while (position > highThreshold) position = (position + step) & tableMask;   /* lowprob area */
160        }   }
161        if (position!=0) return ERROR(GENERIC);   /* position must reach all cells once, otherwise normalizedCounter is incorrect */
162    }
163
164    /* Build Decoding table */
165    {   U32 u;
166        for (u=0; u<tableSize; u++) {
167            FSE_FUNCTION_TYPE const symbol = (FSE_FUNCTION_TYPE)(tableDecode[u].symbol);
168            U32 const nextState = symbolNext[symbol]++;
169            tableDecode[u].nbBits = (BYTE) (tableLog - BIT_highbit32(nextState) );
170            tableDecode[u].newState = (U16) ( (nextState << tableDecode[u].nbBits) - tableSize);
171    }   }
172
173    return 0;
174}
175
176size_t FSE_buildDTable_wksp(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize)
177{
178    return FSE_buildDTable_internal(dt, normalizedCounter, maxSymbolValue, tableLog, workSpace, wkspSize);
179}
180
181
182#ifndef FSE_COMMONDEFS_ONLY
183
184/*-*******************************************************
185*  Decompression (Byte symbols)
186*********************************************************/
187size_t FSE_buildDTable_rle (FSE_DTable* dt, BYTE symbolValue)
188{
189    void* ptr = dt;
190    FSE_DTableHeader* const DTableH = (FSE_DTableHeader*)ptr;
191    void* dPtr = dt + 1;
192    FSE_decode_t* const cell = (FSE_decode_t*)dPtr;
193
194    DTableH->tableLog = 0;
195    DTableH->fastMode = 0;
196
197    cell->newState = 0;
198    cell->symbol = symbolValue;
199    cell->nbBits = 0;
200
201    return 0;
202}
203
204
205size_t FSE_buildDTable_raw (FSE_DTable* dt, unsigned nbBits)
206{
207    void* ptr = dt;
208    FSE_DTableHeader* const DTableH = (FSE_DTableHeader*)ptr;
209    void* dPtr = dt + 1;
210    FSE_decode_t* const dinfo = (FSE_decode_t*)dPtr;
211    const unsigned tableSize = 1 << nbBits;
212    const unsigned tableMask = tableSize - 1;
213    const unsigned maxSV1 = tableMask+1;
214    unsigned s;
215
216    /* Sanity checks */
217    if (nbBits < 1) return ERROR(GENERIC);         /* min size */
218
219    /* Build Decoding Table */
220    DTableH->tableLog = (U16)nbBits;
221    DTableH->fastMode = 1;
222    for (s=0; s<maxSV1; s++) {
223        dinfo[s].newState = 0;
224        dinfo[s].symbol = (BYTE)s;
225        dinfo[s].nbBits = (BYTE)nbBits;
226    }
227
228    return 0;
229}
230
231FORCE_INLINE_TEMPLATE size_t FSE_decompress_usingDTable_generic(
232          void* dst, size_t maxDstSize,
233    const void* cSrc, size_t cSrcSize,
234    const FSE_DTable* dt, const unsigned fast)
235{
236    BYTE* const ostart = (BYTE*) dst;
237    BYTE* op = ostart;
238    BYTE* const omax = op + maxDstSize;
239    BYTE* const olimit = omax-3;
240
241    BIT_DStream_t bitD;
242    FSE_DState_t state1;
243    FSE_DState_t state2;
244
245    /* Init */
246    CHECK_F(BIT_initDStream(&bitD, cSrc, cSrcSize));
247
248    FSE_initDState(&state1, &bitD, dt);
249    FSE_initDState(&state2, &bitD, dt);
250
251#define FSE_GETSYMBOL(statePtr) fast ? FSE_decodeSymbolFast(statePtr, &bitD) : FSE_decodeSymbol(statePtr, &bitD)
252
253    /* 4 symbols per loop */
254    for ( ; (BIT_reloadDStream(&bitD)==BIT_DStream_unfinished) & (op<olimit) ; op+=4) {
255        op[0] = FSE_GETSYMBOL(&state1);
256
257        if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
258            BIT_reloadDStream(&bitD);
259
260        op[1] = FSE_GETSYMBOL(&state2);
261
262        if (FSE_MAX_TABLELOG*4+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
263            { if (BIT_reloadDStream(&bitD) > BIT_DStream_unfinished) { op+=2; break; } }
264
265        op[2] = FSE_GETSYMBOL(&state1);
266
267        if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
268            BIT_reloadDStream(&bitD);
269
270        op[3] = FSE_GETSYMBOL(&state2);
271    }
272
273    /* tail */
274    /* note : BIT_reloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly BIT_DStream_completed */
275    while (1) {
276        if (op>(omax-2)) return ERROR(dstSize_tooSmall);
277        *op++ = FSE_GETSYMBOL(&state1);
278        if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) {
279            *op++ = FSE_GETSYMBOL(&state2);
280            break;
281        }
282
283        if (op>(omax-2)) return ERROR(dstSize_tooSmall);
284        *op++ = FSE_GETSYMBOL(&state2);
285        if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) {
286            *op++ = FSE_GETSYMBOL(&state1);
287            break;
288    }   }
289
290    return op-ostart;
291}
292
293
294size_t FSE_decompress_usingDTable(void* dst, size_t originalSize,
295                            const void* cSrc, size_t cSrcSize,
296                            const FSE_DTable* dt)
297{
298    const void* ptr = dt;
299    const FSE_DTableHeader* DTableH = (const FSE_DTableHeader*)ptr;
300    const U32 fastMode = DTableH->fastMode;
301
302    /* select fast mode (static) */
303    if (fastMode) return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 1);
304    return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 0);
305}
306
307
308size_t FSE_decompress_wksp(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize)
309{
310    return FSE_decompress_wksp_bmi2(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, /* bmi2 */ 0);
311}
312
313typedef struct {
314    short ncount[FSE_MAX_SYMBOL_VALUE + 1];
315    FSE_DTable dtable[]; /* Dynamically sized */
316} FSE_DecompressWksp;
317
318
319FORCE_INLINE_TEMPLATE size_t FSE_decompress_wksp_body(
320        void* dst, size_t dstCapacity,
321        const void* cSrc, size_t cSrcSize,
322        unsigned maxLog, void* workSpace, size_t wkspSize,
323        int bmi2)
324{
325    const BYTE* const istart = (const BYTE*)cSrc;
326    const BYTE* ip = istart;
327    unsigned tableLog;
328    unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;
329    FSE_DecompressWksp* const wksp = (FSE_DecompressWksp*)workSpace;
330
331    DEBUG_STATIC_ASSERT((FSE_MAX_SYMBOL_VALUE + 1) % 2 == 0);
332    if (wkspSize < sizeof(*wksp)) return ERROR(GENERIC);
333
334    /* normal FSE decoding mode */
335    {
336        size_t const NCountLength = FSE_readNCount_bmi2(wksp->ncount, &maxSymbolValue, &tableLog, istart, cSrcSize, bmi2);
337        if (FSE_isError(NCountLength)) return NCountLength;
338        if (tableLog > maxLog) return ERROR(tableLog_tooLarge);
339        assert(NCountLength <= cSrcSize);
340        ip += NCountLength;
341        cSrcSize -= NCountLength;
342    }
343
344    if (FSE_DECOMPRESS_WKSP_SIZE(tableLog, maxSymbolValue) > wkspSize) return ERROR(tableLog_tooLarge);
345    workSpace = wksp->dtable + FSE_DTABLE_SIZE_U32(tableLog);
346    wkspSize -= sizeof(*wksp) + FSE_DTABLE_SIZE(tableLog);
347
348    CHECK_F( FSE_buildDTable_internal(wksp->dtable, wksp->ncount, maxSymbolValue, tableLog, workSpace, wkspSize) );
349
350    {
351        const void* ptr = wksp->dtable;
352        const FSE_DTableHeader* DTableH = (const FSE_DTableHeader*)ptr;
353        const U32 fastMode = DTableH->fastMode;
354
355        /* select fast mode (static) */
356        if (fastMode) return FSE_decompress_usingDTable_generic(dst, dstCapacity, ip, cSrcSize, wksp->dtable, 1);
357        return FSE_decompress_usingDTable_generic(dst, dstCapacity, ip, cSrcSize, wksp->dtable, 0);
358    }
359}
360
361/* Avoids the FORCE_INLINE of the _body() function. */
362static 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)
363{
364    return FSE_decompress_wksp_body(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, 0);
365}
366
367#if DYNAMIC_BMI2
368BMI2_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)
369{
370    return FSE_decompress_wksp_body(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, 1);
371}
372#endif
373
374size_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)
375{
376#if DYNAMIC_BMI2
377    if (bmi2) {
378        return FSE_decompress_wksp_body_bmi2(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize);
379    }
380#endif
381    (void)bmi2;
382    return FSE_decompress_wksp_body_default(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize);
383}
384
385
386typedef FSE_DTable DTable_max_t[FSE_DTABLE_SIZE_U32(FSE_MAX_TABLELOG)];
387
388
389
390#endif   /* FSE_COMMONDEFS_ONLY */
391