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

   FSE : Finite State Entropy encoder

   Copyright (C) 2013-2015, 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 :

    - FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy

    - Public forum : https://groups.google.com/forum/#!forum/lz4c

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

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

*  Includes

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

#include <stdlib.h>     /* malloc, free, qsort */

#include <string.h>     /* memcpy, memset */

#include <stdio.h>      /* printf (debug) */

#include "bitstream.h"

#define FSE_STATIC_LINKING_ONLY

#include "fse.h"

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

*  Error Management

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

#define FSE_STATIC_ASSERT(c) { enum { FSE_static_assert = 1/(int)(!!(c)) }; }   /* use only *after* variable declarations */

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

*  Templates

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

/*

  designed to be included

  for type-specific functions (template emulation in C)

  Objective is to write these functions only once, for improved maintenance

*/

/* safety checks */

#ifndef FSE_FUNCTION_EXTENSION

#  error "FSE_FUNCTION_EXTENSION must be defined"

#endif

#ifndef FSE_FUNCTION_TYPE

#  error "FSE_FUNCTION_TYPE must be defined"

#endif

/* Function names */

#define FSE_CAT(X,Y) X##Y

#define FSE_FUNCTION_NAME(X,Y) FSE_CAT(X,Y)

#define FSE_TYPE_NAME(X,Y) FSE_CAT(X,Y)

/* Function templates */

/* FSE_buildCTable_wksp() :

 * Same as FSE_buildCTable(), but using an externally allocated scratch buffer (`workSpace`).

 * wkspSize should be sized to handle worst case situation, which is `1<<max_tableLog * sizeof(FSE_FUNCTION_TYPE)`

 * workSpace must also be properly aligned with FSE_FUNCTION_TYPE requirements

 */

size_t FSE_buildCTable_wksp(FSE_CTable* ct, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize)

{

    U32 const tableSize = 1 << tableLog;

    U32 const tableMask = tableSize - 1;

    void* const ptr = ct;

    U16* const tableU16 = ( (U16*) ptr) + 2;

    void* const FSCT = ((U32*)ptr) + 1 /* header */ + (tableLog ? tableSize>>1 : 1) ;

    FSE_symbolCompressionTransform* const symbolTT = (FSE_symbolCompressionTransform*) (FSCT);

    U32 const step = FSE_TABLESTEP(tableSize);

    U32 cumul[FSE_MAX_SYMBOL_VALUE+2];

    FSE_FUNCTION_TYPE* const tableSymbol = (FSE_FUNCTION_TYPE*)workSpace;

    U32 highThreshold = tableSize-1;

    /* CTable header */

    if (((size_t)1 << tableLog) * sizeof(FSE_FUNCTION_TYPE) > wkspSize) return ERROR(tableLog_tooLarge);

    tableU16[-2] = (U16) tableLog;

    tableU16[-1] = (U16) maxSymbolValue;

    /* For explanations on how to distribute symbol values over the table :

    *  http://fastcompression.blogspot.fr/2014/02/fse-distributing-symbol-values.html */

    /* symbol start positions */

    {   U32 u;

        cumul[0] = 0;

        for (u=1; u<=maxSymbolValue+1; u++) {

            if (normalizedCounter[u-1]==-1) {  /* Low proba symbol */

                cumul[u] = cumul[u-1] + 1;

                tableSymbol[highThreshold--] = (FSE_FUNCTION_TYPE)(u-1);

            } else {

                cumul[u] = cumul[u-1] + normalizedCounter[u-1];

        }   }

        cumul[maxSymbolValue+1] = tableSize+1;

    }

    /* Spread symbols */

    {   U32 position = 0;

        U32 symbol;

        for (symbol=0; symbol<=maxSymbolValue; symbol++) {

            int nbOccurences;

            for (nbOccurences=0; nbOccurences<normalizedCounter[symbol]; nbOccurences++) {

                tableSymbol[position] = (FSE_FUNCTION_TYPE)symbol;

                position = (position + step) & tableMask;

                while (position > highThreshold) position = (position + step) & tableMask;   /* Low proba area */

        }   }

        if (position!=0) return ERROR(GENERIC);   /* Must have gone through all positions */

    }

    /* Build table */

    {   U32 u; for (u=0; u<tableSize; u++) {

        FSE_FUNCTION_TYPE s = tableSymbol[u];   /* note : static analyzer may not understand tableSymbol is properly initialized */

        tableU16[cumul[s]++] = (U16) (tableSize+u);   /* TableU16 : sorted by symbol order; gives next state value */

    }   }

    /* Build Symbol Transformation Table */

    {   unsigned total = 0;

        unsigned s;

        for (s=0; s<=maxSymbolValue; s++) {

            switch (normalizedCounter[s])

            {

            case  0: break;

            case -1:

            case  1:

                symbolTT[s].deltaNbBits = (tableLog << 16) - (1<<tableLog);

                symbolTT[s].deltaFindState = total - 1;

                total ++;

                break;

            default :

                {

                    U32 const maxBitsOut = tableLog - BIT_highbit32 (normalizedCounter[s]-1);

                    U32 const minStatePlus = normalizedCounter[s] << maxBitsOut;

                    symbolTT[s].deltaNbBits = (maxBitsOut << 16) - minStatePlus;

                    symbolTT[s].deltaFindState = total - normalizedCounter[s];

                    total +=  normalizedCounter[s];

    }   }   }   }

    return 0;

}

size_t FSE_buildCTable(FSE_CTable* ct, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog)

{

    FSE_FUNCTION_TYPE tableSymbol[FSE_MAX_TABLESIZE];   /* memset() is not necessary, even if static analyzer complain about it */

    return FSE_buildCTable_wksp(ct, normalizedCounter, maxSymbolValue, tableLog, tableSymbol, sizeof(tableSymbol));

}

#ifndef FSE_COMMONDEFS_ONLY

/*-**************************************************************

*  FSE NCount encoding-decoding

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

size_t FSE_NCountWriteBound(unsigned maxSymbolValue, unsigned tableLog)

{

    size_t const maxHeaderSize = (((maxSymbolValue+1) * tableLog) >> 3) + 3;

    return maxSymbolValue ? maxHeaderSize : FSE_NCOUNTBOUND;  /* maxSymbolValue==0 ? use default */

}

static size_t FSE_writeNCount_generic (void* header, size_t headerBufferSize,

                                       const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog,

                                       unsigned writeIsSafe)

{

    BYTE* const ostart = (BYTE*) header;

    BYTE* out = ostart;

    BYTE* const oend = ostart + headerBufferSize;

    int nbBits;

    const int tableSize = 1 << tableLog;

    int remaining;

    int threshold;

    U32 bitStream;

    int bitCount;

    unsigned charnum = 0;

    int previous0 = 0;

    bitStream = 0;

    bitCount  = 0;

    /* Table Size */

    bitStream += (tableLog-FSE_MIN_TABLELOG) << bitCount;

    bitCount  += 4;

    /* Init */

    remaining = tableSize+1;   /* +1 for extra accuracy */

    threshold = tableSize;

    nbBits = tableLog+1;

    while (remaining>1) {  /* stops at 1 */

        if (previous0) {

            unsigned start = charnum;

            while (!normalizedCounter[charnum]) charnum++;

            while (charnum >= start+24) {

                start+=24;

                bitStream += 0xFFFFU << bitCount;

                if ((!writeIsSafe) && (out > oend-2)) return ERROR(dstSize_tooSmall);   /* Buffer overflow */

                out[0] = (BYTE) bitStream;

                out[1] = (BYTE)(bitStream>>8);

                out+=2;

                bitStream>>=16;

            }

            while (charnum >= start+3) {

                start+=3;

                bitStream += 3 << bitCount;

                bitCount += 2;

            }

            bitStream += (charnum-start) << bitCount;

            bitCount += 2;

            if (bitCount>16) {

                if ((!writeIsSafe) && (out > oend - 2)) return ERROR(dstSize_tooSmall);   /* Buffer overflow */

                out[0] = (BYTE)bitStream;

                out[1] = (BYTE)(bitStream>>8);

                out += 2;

                bitStream >>= 16;

                bitCount -= 16;

        }   }

            count++;   /* +1 for extra accuracy */

            if (count>=threshold) count += max;   /* [0..max[ [max..threshold[ (...) [threshold+max 2*threshold[ */

            bitStream += count << bitCount;

            bitCount  += nbBits;

            bitCount  -= (count<max);

            previous0  = (count==1);

        }

        if (bitCount>16) {

            if ((!writeIsSafe) && (out > oend - 2)) return ERROR(dstSize_tooSmall);   /* Buffer overflow */

            out[0] = (BYTE)bitStream;

            out[1] = (BYTE)(bitStream>>8);

            out += 2;

            bitStream >>= 16;

            bitCount -= 16;

    }   }

    /* flush remaining bitStream */

    if ((!writeIsSafe) && (out > oend - 2)) return ERROR(dstSize_tooSmall);   /* Buffer overflow */

    out[0] = (BYTE)bitStream;

    out[1] = (BYTE)(bitStream>>8);

    out+= (bitCount+7) /8;

    if (charnum > maxSymbolValue + 1) return ERROR(GENERIC);

    return (out-ostart);

}

size_t FSE_writeNCount (void* buffer, size_t bufferSize, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog)

{

    if (tableLog < FSE_MIN_TABLELOG) return ERROR(GENERIC);   /* Unsupported */

    if (bufferSize < FSE_NCountWriteBound(maxSymbolValue, tableLog))

        return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 0);

    return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 1);

}

/*-**************************************************************

*  Counting histogram

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

/*! FSE_count_simple

    This function counts byte values within `src`, and store the histogram into table `count`.

    It doesn't use any additional memory.

    But this function is unsafe : it doesn't check that all values within `src` can fit into `count`.

    For this reason, prefer using a table `count` with 256 elements.

*/

size_t FSE_count_simple(unsigned* count, unsigned* maxSymbolValuePtr,

                        const void* src, size_t srcSize)

{

    const BYTE* ip = (const BYTE*)src;

    const BYTE* const end = ip + srcSize;

    unsigned maxSymbolValue = *maxSymbolValuePtr;

    unsigned max=0;

    memset(count, 0, (maxSymbolValue+1)*sizeof(*count));

    if (srcSize==0) { *maxSymbolValuePtr = 0; return 0; }

    while (!count[maxSymbolValue]) maxSymbolValue--;

    *maxSymbolValuePtr = maxSymbolValue;

    { U32 s; for (s=0; s<=maxSymbolValue; s++) if (count[s] > max) max = count[s]; }

    return (size_t)max;

}

/* FSE_count_parallel_wksp() :

 * Same as FSE_count_parallel(), but using an externally provided scratch buffer.

static size_t FSE_count_parallel_wksp(

                                unsigned* count, unsigned* maxSymbolValuePtr,

                                const void* source, size_t sourceSize,

                                unsigned checkMax, unsigned* const workSpace)

{

    const BYTE* ip = (const BYTE*)source;

    const BYTE* const iend = ip+sourceSize;

    unsigned maxSymbolValue = *maxSymbolValuePtr;

    unsigned max=0;

    U32* const Counting1 = workSpace;

    U32* const Counting2 = Counting1 + 256;

    U32* const Counting3 = Counting2 + 256;

    U32* const Counting4 = Counting3 + 256;

    /* safety checks */

    if (!sourceSize) {

        memset(count, 0, maxSymbolValue + 1);

        *maxSymbolValuePtr = 0;

        return 0;

    }

    if (!maxSymbolValue) maxSymbolValue = 255;            /* 0 == default */

    /* by stripes of 16 bytes */

    {   U32 cached = MEM_read32(ip); ip += 4;

        while (ip < iend-15) {

            U32 c = cached; cached = MEM_read32(ip); ip += 4;

            Counting1[(BYTE) c     ]++;

            Counting2[(BYTE)(c>>8) ]++;

            Counting3[(BYTE)(c>>16)]++;

            Counting4[       c>>24 ]++;

            c = cached; cached = MEM_read32(ip); ip += 4;

            Counting1[(BYTE) c     ]++;

            Counting2[(BYTE)(c>>8) ]++;

            Counting3[(BYTE)(c>>16)]++;

            Counting4[       c>>24 ]++;

            c = cached; cached = MEM_read32(ip); ip += 4;

            Counting1[(BYTE) c     ]++;

            Counting2[(BYTE)(c>>8) ]++;

            Counting3[(BYTE)(c>>16)]++;

            Counting4[       c>>24 ]++;

            c = cached; cached = MEM_read32(ip); ip += 4;

            Counting1[(BYTE) c     ]++;

            Counting2[(BYTE)(c>>8) ]++;

            Counting3[(BYTE)(c>>16)]++;

            Counting4[       c>>24 ]++;

        }

        ip-=4;

    }

    /* finish last symbols */

    while (ip<iend) Counting1[*ip++]++;

    if (checkMax) {   /* verify stats will fit into destination table */

        U32 s; for (s=255; s>maxSymbolValue; s--) {

            Counting1[s] += Counting2[s] + Counting3[s] + Counting4[s];

            if (Counting1[s]) return ERROR(maxSymbolValue_tooSmall);

    }   }