/*

 * FSE : Finite State Entropy decoder

 * 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.

 *

 * This program is free software; you can redistribute it and/or modify it under

 * the terms of the GNU General Public License version 2 as published by the

 * Free Software Foundation. This program is dual-licensed; you may select

 * either version 2 of the GNU General Public License ("GPL") or BSD license

 * ("BSD").

 *

 * You can contact the author at :

 * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy

 */

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

*  Compiler specifics

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

#define FORCE_INLINE static __always_inline

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

*  Includes

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

#include "bitstream.h"

#include "fse.h"

#include <linux/compiler.h>

#include <linux/kernel.h>

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

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

*  Error Management

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

#define FSE_isError ERR_isError

#define FSE_STATIC_ASSERT(c)                                   \

  {                                                      \

    enum { FSE_static_assert = 1 / (int)(!!(c)) }; \

  } /* use only *after* variable declarations */

/* check and forward error code */

#define CHECK_F(f)                  \

  {                           \

    size_t const e = f; \

    if (FSE_isError(e)) \

      return e;   \

  }

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

*  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 */

size_t FSE_buildDTable_wksp(FSE_DTable *dt, const short *normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void *workspace, size_t workspaceSize)

{

  void *const tdPtr = dt + 1; /* because *dt is unsigned, 32-bits aligned on 32-bits */

  FSE_DECODE_TYPE *const tableDecode = (FSE_DECODE_TYPE *)(tdPtr);

  U16 *symbolNext = (U16 *)workspace;

  U32 const maxSV1 = maxSymbolValue + 1;

  U32 const tableSize = 1 << tableLog;

  U32 highThreshold = tableSize - 1;

  /* Sanity Checks */

  if (workspaceSize < sizeof(U16) * (FSE_MAX_SYMBOL_VALUE + 1))

    return ERROR(tableLog_tooLarge);

  if (maxSymbolValue > FSE_MAX_SYMBOL_VALUE)

    return ERROR(maxSymbolValue_tooLarge);

  if (tableLog > FSE_MAX_TABLELOG)

    return ERROR(tableLog_tooLarge);

  /* Init, lay down lowprob symbols */

  {

    FSE_DTableHeader DTableH;

    DTableH.tableLog = (U16)tableLog;

    DTableH.fastMode = 1;

    {

      S16 const largeLimit = (S16)(1 << (tableLog - 1));

      U32 s;

      for (s = 0; s < maxSV1; s++) {

        if (normalizedCounter[s] == -1) {

          tableDecode[highThreshold--].symbol = (FSE_FUNCTION_TYPE)s;

          symbolNext[s] = 1;

        } else {

          if (normalizedCounter[s] >= largeLimit)

            DTableH.fastMode = 0;

          symbolNext[s] = normalizedCounter[s];

        }

      }

    }

    memcpy(dt, &DTableH, sizeof(DTableH));

  }

  /* Spread symbols */

  {

    U32 const tableMask = tableSize - 1;

    U32 const step = FSE_TABLESTEP(tableSize);

    U32 s, position = 0;

    for (s = 0; s < maxSV1; s++) {

      int i;

      for (i = 0; i < normalizedCounter[s]; i++) {

        tableDecode[position].symbol = (FSE_FUNCTION_TYPE)s;

        position = (position + step) & tableMask;

        while (position > highThreshold)

          position = (position + step) & tableMask; /* lowprob area */

      }

    }

    if (position != 0)

      return ERROR(GENERIC); /* position must reach all cells once, otherwise normalizedCounter is incorrect */

  }

  /* Build Decoding table */

  {

    U32 u;

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

      FSE_FUNCTION_TYPE const symbol = (FSE_FUNCTION_TYPE)(tableDecode[u].symbol);

      U16 nextState = symbolNext[symbol]++;

      tableDecode[u].nbBits = (BYTE)(tableLog - BIT_highbit32((U32)nextState));

      tableDecode[u].newState = (U16)((nextState << tableDecode[u].nbBits) - tableSize);

    }

  }

  return 0;

}

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

*  Decompression (Byte symbols)

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

size_t FSE_buildDTable_rle(FSE_DTable *dt, BYTE symbolValue)

{

  void *ptr = dt;

  FSE_DTableHeader *const DTableH = (FSE_DTableHeader *)ptr;

  void *dPtr = dt + 1;

  FSE_decode_t *const cell = (FSE_decode_t *)dPtr;

  DTableH->tableLog = 0;

  DTableH->fastMode = 0;

  cell->newState = 0;

  cell->symbol = symbolValue;

  cell->nbBits = 0;

  return 0;

}

size_t FSE_buildDTable_raw(FSE_DTable *dt, unsigned nbBits)

{

  void *ptr = dt;

  FSE_DTableHeader *const DTableH = (FSE_DTableHeader *)ptr;

  void *dPtr = dt + 1;

  FSE_decode_t *const dinfo = (FSE_decode_t *)dPtr;

  const unsigned tableSize = 1 << nbBits;

  const unsigned tableMask = tableSize - 1;

  const unsigned maxSV1 = tableMask + 1;

  unsigned s;

  /* Sanity checks */

  if (nbBits < 1)

    return ERROR(GENERIC); /* min size */

  /* Build Decoding Table */

  DTableH->tableLog = (U16)nbBits;

  DTableH->fastMode = 1;

  for (s = 0; s < maxSV1; s++) {

    dinfo[s].newState = 0;

    dinfo[s].symbol = (BYTE)s;

    dinfo[s].nbBits = (BYTE)nbBits;

  }

  return 0;

}

FORCE_INLINE size_t FSE_decompress_usingDTable_generic(void *dst, size_t maxDstSize, const void *cSrc, size_t cSrcSize, const FSE_DTable *dt,

                   const unsigned fast)

{

  BYTE *const ostart = (BYTE *)dst;

  BYTE *op = ostart;

  BYTE *const omax = op + maxDstSize;

  BYTE *const olimit = omax - 3;

  BIT_DStream_t bitD;

  FSE_DState_t state1;

  FSE_DState_t state2;

  /* Init */

  CHECK_F(BIT_initDStream(&bitD, cSrc, cSrcSize));

  FSE_initDState(&state1, &bitD, dt);

  FSE_initDState(&state2, &bitD, dt);

#define FSE_GETSYMBOL(statePtr) fast ? FSE_decodeSymbolFast(statePtr, &bitD) : FSE_decodeSymbol(statePtr, &bitD)

  /* 4 symbols per loop */

  for (; (BIT_reloadDStream(&bitD) == BIT_DStream_unfinished) & (op < olimit); op += 4) {

    op[0] = FSE_GETSYMBOL(&state1);

    if (FSE_MAX_TABLELOG * 2 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */

      BIT_reloadDStream(&bitD);

    op[1] = FSE_GETSYMBOL(&state2);

    if (FSE_MAX_TABLELOG * 4 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */

    {

      if (BIT_reloadDStream(&bitD) > BIT_DStream_unfinished) {

        op += 2;

        break;

      }

    }

    op[2] = FSE_GETSYMBOL(&state1);

    if (FSE_MAX_TABLELOG * 2 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */

      BIT_reloadDStream(&bitD);

    op[3] = FSE_GETSYMBOL(&state2);

  }

  /* tail */

  /* note : BIT_reloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly BIT_DStream_completed */

  while (1) {

    if (op > (omax - 2))

      return ERROR(dstSize_tooSmall);

    *op++ = FSE_GETSYMBOL(&state1);

    if (BIT_reloadDStream(&bitD) == BIT_DStream_overflow) {

      *op++ = FSE_GETSYMBOL(&state2);

      break;

    }

    if (op > (omax - 2))

      return ERROR(dstSize_tooSmall);

    *op++ = FSE_GETSYMBOL(&state2);

    if (BIT_reloadDStream(&bitD) == BIT_DStream_overflow) {

      *op++ = FSE_GETSYMBOL(&state1);

      break;

    }

  }

  return op - ostart;

}

size_t FSE_decompress_usingDTable(void *dst, size_t originalSize, const void *cSrc, size_t cSrcSize, const FSE_DTable *dt)

{

  const void *ptr = dt;

  const FSE_DTableHeader *DTableH = (const FSE_DTableHeader *)ptr;

  const U32 fastMode = DTableH->fastMode;

  /* select fast mode (static) */

  if (fastMode)

    return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 1);

  return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 0);

}

size_t FSE_decompress_wksp(void *dst, size_t dstCapacity, const void *cSrc, size_t cSrcSize, unsigned maxLog, void *workspace, size_t workspaceSize)

{

  const BYTE *const istart = (const BYTE *)cSrc;

  const BYTE *ip = istart;

  unsigned tableLog;

  unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;

  size_t NCountLength;

  FSE_DTable *dt;

  short *counting;

  size_t spaceUsed32 = 0;

  FSE_STATIC_ASSERT(sizeof(FSE_DTable) == sizeof(U32));

  dt = (FSE_DTable *)((U32 *)workspace + spaceUsed32);

  spaceUsed32 += FSE_DTABLE_SIZE_U32(maxLog);

  counting = (short *)((U32 *)workspace + spaceUsed32);

  spaceUsed32 += ALIGN(sizeof(short) * (FSE_MAX_SYMBOL_VALUE + 1), sizeof(U32)) >> 2;

  if ((spaceUsed32 << 2) > workspaceSize)

    return ERROR(tableLog_tooLarge);

  workspace = (U32 *)workspace + spaceUsed32;

  workspaceSize -= (spaceUsed32 << 2);

  /* normal FSE decoding mode */

  NCountLength = FSE_readNCount(counting, &maxSymbolValue, &tableLog, istart, cSrcSize);

  if (FSE_isError(NCountLength))

    return NCountLength;

  // if (NCountLength >= cSrcSize) return ERROR(srcSize_wrong);   /* too small input size; supposed to be already checked in NCountLength, only remaining

  // case : NCountLength==cSrcSize */

  if (tableLog > maxLog)

    return ERROR(tableLog_tooLarge);

  ip += NCountLength;

  cSrcSize -= NCountLength;

  CHECK_F(FSE_buildDTable_wksp(dt, counting, maxSymbolValue, tableLog, workspace, workspaceSize));

  return FSE_decompress_usingDTable(dst, dstCapacity, ip, cSrcSize, dt); /* always return, even if it is an error code */

}