LXR linux/lib/zstd/common/fse

   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[1]; /* 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
 368TARGET_ATTRIBUTE("bmi2") 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