lib/common/zstd_common.c

/*
    Common functions of Zstd compression library
    Copyright (C) 2015-2016, Yann Collet.

    BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are
    met:
    * Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above
    copyright notice, this list of conditions and the following disclaimer
    in the documentation and/or other materials provided with the
    distribution.
    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    You can contact the author at :
    - zstd homepage : http://www.zstd.net/
*/


/* *************************************
*  Dependencies
***************************************/
#include <stdlib.h>
#include "mem.h"
#include "fse_static.h"  /* FSE_MIN_TABLELOG */
#include "error_private.h"
#include "zstd.h" /* declaration of ZSTD_isError, ZSTD_getErrorName */
#include "zbuff.h" /* declaration of ZBUFF_isError, ZBUFF_getErrorName */
#include "fse.h" /* declaration of FSE_isError, FSE_getErrorName */
#include "huf.h" /* declaration of HUF_isError, HUF_getErrorName */


/*-****************************************
*  ZSTD Error Management
******************************************/
/*! ZSTD_isError() :
*   tells if a return value is an error code */
unsigned ZSTD_isError(size_t code) { return ERR_isError(code); }

/*! ZSTD_getError() :
*   convert a `size_t` function result into a proper ZSTD_errorCode enum */
ZSTD_ErrorCode ZSTD_getErrorCode(size_t code) { return ERR_getErrorCode(code); }

/*! ZSTD_getErrorName() :
*   provides error code string (useful for debugging) */
const char* ZSTD_getErrorName(size_t code) { return ERR_getErrorName(code); }

/*! ZSTD_getErrorName() :
*   provides error code string (useful for debugging) */
const char* ZSTD_getErrorString(ZSTD_ErrorCode code) { return ERR_getErrorName(code); }


/*-****************************************
*  FSE Error Management
******************************************/
unsigned FSE_isError(size_t code) { return ERR_isError(code); }

const char* FSE_getErrorName(size_t code) { return ERR_getErrorName(code); }


/* **************************************************************
*  HUF Error Management
****************************************************************/
unsigned HUF_isError(size_t code) { return ERR_isError(code); }

const char* HUF_getErrorName(size_t code) { return ERR_getErrorName(code); }


/* **************************************************************
*  ZBUFF Error Management
****************************************************************/
unsigned ZBUFF_isError(size_t errorCode) { return ERR_isError(errorCode); }

const char* ZBUFF_getErrorName(size_t errorCode) { return ERR_getErrorName(errorCode); }


/*-**************************************************************
*  FSE NCount encoding-decoding
****************************************************************/
static short FSE_abs(short a) { return a<0 ? -a : a; }

size_t FSE_readNCount (short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
                 const void* headerBuffer, size_t hbSize)
{
    const BYTE* const istart = (const BYTE*) headerBuffer;
    const BYTE* const iend = istart + hbSize;
    const BYTE* ip = istart;
    int nbBits;
    int remaining;
    int threshold;
    U32 bitStream;
    int bitCount;
    unsigned charnum = 0;
    int previous0 = 0;

    if (hbSize < 4) return ERROR(srcSize_wrong);
    bitStream = MEM_readLE32(ip);
    nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG;   /* extract tableLog */
    if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX) return ERROR(tableLog_tooLarge);
    bitStream >>= 4;
    bitCount = 4;
    *tableLogPtr = nbBits;
    remaining = (1<<nbBits)+1;
    threshold = 1<<nbBits;
    nbBits++;

    while ((remaining>1) && (charnum<=*maxSVPtr)) {
        if (previous0) {
            unsigned n0 = charnum;
            while ((bitStream & 0xFFFF) == 0xFFFF) {
                n0+=24;
                if (ip < iend-5) {
                    ip+=2;
                    bitStream = MEM_readLE32(ip) >> bitCount;
                } else {
                    bitStream >>= 16;
                    bitCount+=16;
            }   }
            while ((bitStream & 3) == 3) {
                n0+=3;
                bitStream>>=2;
                bitCount+=2;
            }
            n0 += bitStream & 3;
            bitCount += 2;
            if (n0 > *maxSVPtr) return ERROR(maxSymbolValue_tooSmall);
            while (charnum < n0) normalizedCounter[charnum++] = 0;
            if ((ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {
                ip += bitCount>>3;
                bitCount &= 7;
                bitStream = MEM_readLE32(ip) >> bitCount;
            }
            else
                bitStream >>= 2;
        }
        {   short const max = (short)((2*threshold-1)-remaining);
            short count;

            if ((bitStream & (threshold-1)) < (U32)max) {
                count = (short)(bitStream & (threshold-1));
                bitCount   += nbBits-1;
            } else {
                count = (short)(bitStream & (2*threshold-1));
                if (count >= threshold) count -= max;
                bitCount   += nbBits;
            }

            count--;   /* extra accuracy */
            remaining -= FSE_abs(count);
            normalizedCounter[charnum++] = count;
            previous0 = !count;
            while (remaining < threshold) {
                nbBits--;
                threshold >>= 1;
            }

            if ((ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {
                ip += bitCount>>3;
                bitCount &= 7;
            } else {
                bitCount -= (int)(8 * (iend - 4 - ip));
                ip = iend - 4;
            }
            bitStream = MEM_readLE32(ip) >> (bitCount & 31);
    }   }
    if (remaining != 1) return ERROR(GENERIC);
    *maxSVPtr = charnum-1;

    ip += (bitCount+7)>>3;
    if ((size_t)(ip-istart) > hbSize) return ERROR(srcSize_wrong);
    return ip-istart;
}