path: root/lib/zstd/decompress/huf_decompress.c

/* ******************************************************************
 * huff0 huffman decoder,
 * part of Finite State Entropy library
 * Copyright (c) Yann Collet, Facebook, Inc.
 *
 *  You can contact the author at :
 *  - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy
 *
 * 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.
****************************************************************** */

/* **************************************************************
*  Dependencies
****************************************************************/
#include "../common/zstd_deps.h"  /* ZSTD_memcpy, ZSTD_memset */
#include "../common/compiler.h"
#include "../common/bitstream.h"  /* BIT_* */
#include "../common/fse.h"        /* to compress headers */
#define HUF_STATIC_LINKING_ONLY
#include "../common/huf.h"
#include "../common/error_private.h"

/* **************************************************************
*  Macros
****************************************************************/

/* These two optional macros force the use one way or another of the two
 * Huffman decompression implementations. You can't force in both directions
 * at the same time.
 */
#if defined(HUF_FORCE_DECOMPRESS_X1) && \
    defined(HUF_FORCE_DECOMPRESS_X2)
#error "Cannot force the use of the X1 and X2 decoders at the same time!"
#endif


/* **************************************************************
*  Error Management
****************************************************************/
#define HUF_isError ERR_isError


/* **************************************************************
*  Byte alignment for workSpace management
****************************************************************/
#define HUF_ALIGN(x, a)         HUF_ALIGN_MASK((x), (a) - 1)
#define HUF_ALIGN_MASK(x, mask) (((x) + (mask)) & ~(mask))


/* **************************************************************
*  BMI2 Variant Wrappers
****************************************************************/
#if DYNAMIC_BMI2

#define HUF_DGEN(fn)                                                        \
                                                                            \
    static size_t fn##_default(                                             \
                  void* dst,  size_t dstSize,                               \
            const void* cSrc, size_t cSrcSize,                              \
            const HUF_DTable* DTable)                                       \
    {                                                                       \
        return fn##_body(dst, dstSize, cSrc, cSrcSize, DTable);             \
    }                                                                       \
                                                                            \
    static TARGET_ATTRIBUTE("bmi2") size_t fn##_bmi2(                       \
                  void* dst,  size_t dstSize,                               \
            const void* cSrc, size_t cSrcSize,                              \
            const HUF_DTable* DTable)                                       \
    {                                                                       \
        return fn##_body(dst, dstSize, cSrc, cSrcSize, DTable);             \
    }                                                                       \
                                                                            \
    static size_t fn(void* dst, size_t dstSize, void const* cSrc,           \
                     size_t cSrcSize, HUF_DTable const* DTable, int bmi2)   \
    {                                                                       \
        if (bmi2) {                                                         \
            return fn##_bmi2(dst, dstSize, cSrc, cSrcSize, DTable);         \
        }                                                                   \
        return fn##_default(dst, dstSize, cSrc, cSrcSize, DTable);          \
    }

#else

#define HUF_DGEN(fn)                                                        \
    static size_t fn(void* dst, size_t dstSize, void const* cSrc,           \
                     size_t cSrcSize, HUF_DTable const* DTable, int bmi2)   \
    {                                                                       \
        (void)bmi2;                                                         \
        return fn##_body(dst, dstSize, cSrc, cSrcSize, DTable);             \
    }

#endif


/*-***************************/
/*  generic DTableDesc       */
/*-***************************/
typedef struct { BYTE maxTableLog; BYTE tableType; BYTE tableLog; BYTE reserved; } DTableDesc;

static DTableDesc HUF_getDTableDesc(const HUF_DTable* table)
{
    DTableDesc dtd;
    ZSTD_memcpy(&dtd, table, sizeof(dtd));
    return dtd;
}


#ifndef HUF_FORCE_DECOMPRESS_X2

/*-***************************/
/*  single-symbol decoding   */
/*-***************************/
typedef struct { BYTE byte; BYTE nbBits; } HUF_DEltX1;   /* single-symbol decoding */

/*
 * Packs 4 HUF_DEltX1 structs into a U64. This is used to lay down 4 entries at
 * a time.
 */
static U64 HUF_DEltX1_set4(BYTE symbol, BYTE nbBits) {
    U64 D4;
    if (MEM_isLittleEndian()) {
        D4 = symbol + (nbBits << 8);
    } else {
        D4 = (symbol << 8) + nbBits;
    }
    D4 *= 0x0001000100010001ULL;
    return D4;
}

typedef struct {
        U32 rankVal[HUF_TABLELOG_ABSOLUTEMAX + 1];
        U32 rankStart[HUF_TABLELOG_ABSOLUTEMAX + 1];
        U32 statsWksp[HUF_READ_STATS_WORKSPACE_SIZE_U32];
        BYTE symbols[HUF_SYMBOLVALUE_MAX + 1];
        BYTE huffWeight[HUF_SYMBOLVALUE_MAX + 1];
} HUF_ReadDTableX1_Workspace;


size_t HUF_readDTableX1_wksp(HUF_DTable* DTable, const void* src, size_t srcSize, void* workSpace, size_t wkspSize)
{
    return HUF_readDTableX1_wksp_bmi2(DTable, src, srcSize, workSpace, wkspSize, /* bmi2 */ 0);
}

size_t HUF_readDTableX1_wksp_bmi2(HUF_DTable* DTable, const void* src, size_t srcSize, void* workSpace, size_t wkspSize, int bmi2)
{
    U32 tableLog = 0;
    U32 nbSymbols = 0;
    size_t iSize;
    void* const dtPtr = DTable + 1;
    HUF_DEltX1* const dt = (HUF_DEltX1*)dtPtr;