path: root/lz4_encoder.h

/*

   LZ4 Encoder - Part of LZ4 compression algorithm

   Copyright (C) 2011-2013, 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 :

   - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html

   - LZ4 source repository : http://code.google.com/p/lz4/

*/

/* lz4_encoder.h must be included into lz4.c

   The objective of this file is to create a single LZ4 compression function source

   which will be instanciated multiple times with minor variations

   depending on a set of #define.

*/



//****************************

// Check required defines

//****************************


#ifndef FUNCTION_NAME

#  error "FUNTION_NAME is not defined"

#endif



//****************************

// Local definitions

//****************************


#ifdef COMPRESS_64K

#  define HASHLOG (MEMORY_USAGE-1)

#  define CURRENT_H_TYPE U16

#  define CURRENTBASE(base) const BYTE* const base = ip

#else

#  define HASHLOG (MEMORY_USAGE-2)

#  define CURRENT_H_TYPE HTYPE

#  define CURRENTBASE(base) INITBASE(base)

#endif


#define HASHTABLE_NBCELLS  (1U<<HASHLOG)

#define LZ4_HASH(i)        (((i) * 2654435761U) >> ((MINMATCH*8)-HASHLOG))

#define LZ4_HASHVALUE(p)   LZ4_HASH(A32(p))




//****************************

// Function code

//****************************


int FUNCTION_NAME(
#ifdef USE_HEAPMEMORY

                 void* ctx,
#endif

                 const char* source,
                 char* dest,
                 int inputSize
#ifdef LIMITED_OUTPUT

                ,int maxOutputSize
#endif

                 )
{
#ifdef USE_HEAPMEMORY

    CURRENT_H_TYPE* HashTable = (CURRENT_H_TYPE*)ctx;
#else

    CURRENT_H_TYPE HashTable[HASHTABLE_NBCELLS] = {0};
#endif


    const BYTE* ip = (BYTE*) source;
    CURRENTBASE(base);
    const BYTE* anchor = ip;
    const BYTE* const iend = ip + inputSize;
    const BYTE* const mflimit = iend - MFLIMIT;
#define matchlimit (iend - LASTLITERALS)


    BYTE* op = (BYTE*) dest;
#ifdef LIMITED_OUTPUT

    BYTE* const oend = op + maxOutputSize;
#endif


    int length;
    const int skipStrength = SKIPSTRENGTH;
    U32 forwardH;


    // Init

    if (inputSize<MINLENGTH) goto _last_literals;
#ifdef COMPRESS_64K

    if (inputSize>=LZ4_64KLIMIT) return 0;   // Size too large (not within 64K limit)

#endif

#ifdef USE_HEAPMEMORY

    memset((void*)HashTable, 0, HASHTABLESIZE);
#endif


    // First Byte

    HashTable[LZ4_HASHVALUE(ip)] = (CURRENT_H_TYPE)(ip - base);
    ip++; forwardH = LZ4_HASHVALUE(ip);

    // Main Loop

    for ( ; ; )
    {
        int findMatchAttempts = (1U << skipStrength) + 3;
        const BYTE* forwardIp = ip;
        const BYTE* ref;
        BYTE* token;

        // Find a match

        do {
            U32 h = forwardH;
            int step = findMatchAttempts++ >> skipStrength;
            ip = forwardIp;
            forwardIp = ip + step;

            if unlikely(forwardIp > mflimit) { goto _last_literals; }

            forwardH = LZ4_HASHVALUE(forwardIp);
            ref = base + HashTable[h];
            HashTable[h] = (CURRENT_H_TYPE)(ip - base);

        } while ((ref < ip - MAX_DISTANCE) || (A32(ref) != A32(ip)));

        // Catch up

        while ((ip>anchor) && (ref>(BYTE*)source) && unlikely(ip[-1]==ref[-1])) { ip--; ref--; }

        // Encode Literal length

        length = (int)(ip - anchor);
        token = op++;
#ifdef LIMITED_OUTPUT

        if unlikely(op + length + (2 + 1 + LASTLITERALS) + (length>>8) > oend) return 0;   // Check output limit

#endif

        if (length>=(int)RUN_MASK) 
        { 
            int len = length-RUN_MASK; 
            *token=(RUN_MASK<<ML_BITS); 
            for(; len >= 255 ; len-=255) *op++ = 255; 
            *op++ = (BYTE)len; 
        }
        else *token = (BYTE)(length<<ML_BITS);

        // Copy Literals

        LZ4_BLINDCOPY(anchor, op, length);

_next_match:
        // Encode Offset

        LZ4_WRITE_LITTLEENDIAN_16(op,(U16)(ip-ref));

        // Start Counting

        ip+=MINMATCH; ref+=MINMATCH;    // MinMatch already verified

        anchor = ip;
        while likely(ip<matchlimit-(STEPSIZE-1))
        {
            size_t diff = AARCH(ref) ^ AARCH(ip);
            if (!diff) { ip+=STEPSIZE; ref+=STEPSIZE; continue; }
            ip += LZ4_NbCommonBytes(diff);
            goto _endCount;
        }
        if (LZ4_ARCH64) if ((ip<(matchlimit-3)) && (A32(ref) == A32(ip))) { ip+=4; ref+=4; }
        if ((ip<(matchlimit-1)) && (A16(ref) == A16(ip))) { ip+=2; ref+=2; }
        if ((ip<matchlimit) && (*ref == *ip)) ip++;
_endCount:

        // Encode MatchLength

        length = (int)(ip - anchor);
#ifdef LIMITED_OUTPUT

        if unlikely(op + (1 + LASTLITERALS) + (length>>8) > oend) return 0;    // Check output limit

#endif

        if (length>=(int)ML_MASK) 
        { 
            *token += ML_MASK; 
            length -= ML_MASK; 
            for (; length > 509 ; length-=510) { *op++ = 255; *op++ = 255; } 
            if (length >= 255) { length-=255; *op++ = 255; } 
            *op++ = (BYTE)length; 
        }
        else *token += (BYTE)(length);

        // Test end of chunk

        if (ip > mflimit) { anchor = ip;  break; }

        // Fill table

        HashTable[LZ4_HASHVALUE(ip-2)] = (CURRENT_H_TYPE)(ip - 2 - base);

        // Test next position

        ref = base + HashTable[LZ4_HASHVALUE(ip)];
        HashTable[LZ4_HASHVALUE(ip)] = (CURRENT_H_TYPE)(ip - base);
        if ((ref >= ip - MAX_DISTANCE) && (A32(ref) == A32(ip))) { token = op++; *token=0; goto _next_match; }

        // Prepare next loop

        anchor = ip++;
        forwardH = LZ4_HASHVALUE(ip);
    }

_last_literals:
    // Encode Last Literals

    {
        int lastRun = (int)(iend - anchor);
#ifdef LIMITED_OUTPUT

        if (((char*)op - dest) + lastRun + 1 + ((lastRun+255-RUN_MASK)/255) > (U32)maxOutputSize) return 0;  // Check output limit

#endif

        if (lastRun>=(int)RUN_MASK) { *op++=(RUN_MASK<<ML_BITS); lastRun-=RUN_MASK; for(; lastRun >= 255 ; lastRun-=255) *op++ = 255; *op++ = (BYTE) lastRun; }
        else *op++ = (BYTE)(lastRun<<ML_BITS);
        memcpy(op, anchor, iend - anchor);
        op += iend-anchor;
    }

    // End

    return (int) (((char*)op)-dest);
}



//****************************

// Clean defines

//****************************


// Required defines

#undef FUNCTION_NAME


// Locally Generated

#undef HASHLOG

#undef HASHTABLE_NBCELLS

#undef LZ4_HASH

#undef LZ4_HASHVALUE

#undef CURRENT_H_TYPE

#undef CURRENTBASE


// Optional defines

#ifdef LIMITED_OUTPUT

#undef LIMITED_OUTPUT

#endif


#ifdef USE_HEAPMEMORY

#undef USE_HEAPMEMORY

#endif