huffman.c

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/********************************************************************
 *                                                                  *
 * THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE.   *
 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
 *                                                                  *
 * THE Theora SOURCE CODE IS COPYRIGHT (C) 2002-2003                *
 * by the Xiph.Org Foundation http://www.xiph.org/                  *
 *                                                                  *
 ********************************************************************

  function:
  last mod: $Id: huffman.c 11442 2006-05-27 17:28:08Z giles $

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

#include <stdlib.h>
#include <stdio.h>
#include "codec_internal.h"
#include "hufftables.h"

static void CreateHuffmanList(HUFF_ENTRY ** HuffRoot,
                              ogg_uint32_t HIndex,
                              const ogg_uint32_t *FreqList ) {
  int i;
  HUFF_ENTRY *entry_ptr;
  HUFF_ENTRY *search_ptr;

  /* Create a HUFF entry for token zero. */
  HuffRoot[HIndex] = (HUFF_ENTRY *)_ogg_calloc(1,sizeof(*HuffRoot[HIndex]));

  HuffRoot[HIndex]->Previous = NULL;
  HuffRoot[HIndex]->Next = NULL;
  HuffRoot[HIndex]->ZeroChild = NULL;
  HuffRoot[HIndex]->OneChild = NULL;
  HuffRoot[HIndex]->Value = 0;
  HuffRoot[HIndex]->Frequency = FreqList[0];

  if ( HuffRoot[HIndex]->Frequency == 0 )
    HuffRoot[HIndex]->Frequency = 1;

  /* Now add entries for all the other possible tokens. */
  for ( i = 1; i < MAX_ENTROPY_TOKENS; i++ ) {
    entry_ptr = (HUFF_ENTRY *)_ogg_calloc(1,sizeof(*entry_ptr));

    entry_ptr->Value = i;
    entry_ptr->Frequency = FreqList[i];
    entry_ptr->ZeroChild = NULL;
    entry_ptr->OneChild = NULL;

    /* Force min value of 1. This prevents the tree getting too deep. */
    if ( entry_ptr->Frequency == 0 )
      entry_ptr->Frequency = 1;

    if ( entry_ptr->Frequency <= HuffRoot[HIndex]->Frequency ){
      entry_ptr->Next = HuffRoot[HIndex];
      HuffRoot[HIndex]->Previous = entry_ptr;
      entry_ptr->Previous = NULL;
      HuffRoot[HIndex] = entry_ptr;
    }else{
      search_ptr = HuffRoot[HIndex];
      while ( (search_ptr->Next != NULL) &&
              (search_ptr->Frequency < entry_ptr->Frequency) ){
        search_ptr = (HUFF_ENTRY *)search_ptr->Next;
      }

      if ( search_ptr->Frequency < entry_ptr->Frequency ){
        entry_ptr->Next = NULL;
        entry_ptr->Previous = search_ptr;
        search_ptr->Next = entry_ptr;
      }else{
        entry_ptr->Next = search_ptr;
        entry_ptr->Previous = search_ptr->Previous;
        search_ptr->Previous->Next = entry_ptr;
        search_ptr->Previous = entry_ptr;
      }
    }
  }
}

static void CreateCodeArray( HUFF_ENTRY * HuffRoot,
                      ogg_uint32_t *HuffCodeArray,
                      unsigned char *HuffCodeLengthArray,
                      ogg_uint32_t CodeValue,
                      unsigned char CodeLength ) {

  /* If we are at a leaf then fill in a code array entry. */
  if ( ( HuffRoot->ZeroChild == NULL ) && ( HuffRoot->OneChild == NULL ) ){
    HuffCodeArray[HuffRoot->Value] = CodeValue;
    HuffCodeLengthArray[HuffRoot->Value] = CodeLength;
  }else{
    /* Recursive calls to scan down the tree. */
    CodeLength++;
    CreateCodeArray(HuffRoot->ZeroChild, HuffCodeArray, HuffCodeLengthArray,
                    ((CodeValue << 1) + 0), CodeLength);
    CreateCodeArray(HuffRoot->OneChild, HuffCodeArray, HuffCodeLengthArray,
                    ((CodeValue << 1) + 1), CodeLength);
  }
}

static void  BuildHuffmanTree( HUFF_ENTRY **HuffRoot,
                        ogg_uint32_t *HuffCodeArray,
                        unsigned char *HuffCodeLengthArray,
                        ogg_uint32_t HIndex,
                        const ogg_uint32_t *FreqList ){

  HUFF_ENTRY *entry_ptr;
  HUFF_ENTRY *search_ptr;

  /* First create a sorted linked list representing the frequencies of
     each token. */
  CreateHuffmanList( HuffRoot, HIndex, FreqList );

  /* Now build the tree from the list. */

  /* While there are at least two items left in the list. */
  while ( HuffRoot[HIndex]->Next != NULL ){
    /* Create the new node as the parent of the first two in the list. */
    entry_ptr = (HUFF_ENTRY *)_ogg_calloc(1,sizeof(*entry_ptr));
    entry_ptr->Value = -1;
    entry_ptr->Frequency = HuffRoot[HIndex]->Frequency +
      HuffRoot[HIndex]->Next->Frequency ;
    entry_ptr->ZeroChild = HuffRoot[HIndex];
    entry_ptr->OneChild = HuffRoot[HIndex]->Next;

    /* If there are still more items in the list then insert the new
       node into the list. */
    if (entry_ptr->OneChild->Next != NULL ){
      /* Set up the provisional 'new root' */
      HuffRoot[HIndex] = entry_ptr->OneChild->Next;
      HuffRoot[HIndex]->Previous = NULL;

      /* Now scan through the remaining list to insert the new entry
         at the appropriate point. */
      if ( entry_ptr->Frequency <= HuffRoot[HIndex]->Frequency ){
        entry_ptr->Next = HuffRoot[HIndex];
        HuffRoot[HIndex]->Previous = entry_ptr;
        entry_ptr->Previous = NULL;
        HuffRoot[HIndex] = entry_ptr;
      }else{
        search_ptr = HuffRoot[HIndex];
        while ( (search_ptr->Next != NULL) &&
                (search_ptr->Frequency < entry_ptr->Frequency) ){
          search_ptr = search_ptr->Next;
        }

        if ( search_ptr->Frequency < entry_ptr->Frequency ){
          entry_ptr->Next = NULL;
          entry_ptr->Previous = search_ptr;
          search_ptr->Next = entry_ptr;
        }else{
          entry_ptr->Next = search_ptr;
          entry_ptr->Previous = search_ptr->Previous;
          search_ptr->Previous->Next = entry_ptr;
          search_ptr->Previous = entry_ptr;
        }
      }
    }else{
      /* Build has finished. */
      entry_ptr->Next = NULL;
      entry_ptr->Previous = NULL;
      HuffRoot[HIndex] = entry_ptr;
    }

    /* Delete the Next/Previous properties of the children (PROB NOT NEC). */
    entry_ptr->ZeroChild->Next = NULL;
    entry_ptr->ZeroChild->Previous = NULL;
    entry_ptr->OneChild->Next = NULL;
    entry_ptr->OneChild->Previous = NULL;

  }

  /* Now build a code array from the tree. */
  CreateCodeArray( HuffRoot[HIndex], HuffCodeArray,
                   HuffCodeLengthArray, 0, 0);
}

static void  DestroyHuffTree(HUFF_ENTRY *root_ptr){
  if (root_ptr){
    if ( root_ptr->ZeroChild )
      DestroyHuffTree(root_ptr->ZeroChild);

    if ( root_ptr->OneChild )
      DestroyHuffTree(root_ptr->OneChild);

    _ogg_free(root_ptr);
  }
}

void ClearHuffmanSet( PB_INSTANCE *pbi ){
  int i;

  ClearHuffmanTrees(pbi->HuffRoot_VP3x);

  for ( i = 0; i < NUM_HUFF_TABLES; i++ )
    if (pbi->HuffCodeArray_VP3x[i])
      _ogg_free (pbi->HuffCodeArray_VP3x[i]);

  for ( i = 0; i < NUM_HUFF_TABLES; i++ )
    if (pbi->HuffCodeLengthArray_VP3x[i])
      _ogg_free (pbi->HuffCodeLengthArray_VP3x[i]);
}

void InitHuffmanSet( PB_INSTANCE *pbi ){
  int i;

  ClearHuffmanSet(pbi);

  pbi->ExtraBitLengths_VP3x = ExtraBitLengths_VP31;

  for ( i = 0; i < NUM_HUFF_TABLES; i++ ){
    pbi->HuffCodeArray_VP3x[i] =
      _ogg_calloc(MAX_ENTROPY_TOKENS,
                  sizeof(*pbi->HuffCodeArray_VP3x[i]));
    pbi->HuffCodeLengthArray_VP3x[i] =
      _ogg_calloc(MAX_ENTROPY_TOKENS,
                  sizeof(*pbi->HuffCodeLengthArray_VP3x[i]));
    BuildHuffmanTree( pbi->HuffRoot_VP3x,
                      pbi->HuffCodeArray_VP3x[i],
                      pbi->HuffCodeLengthArray_VP3x[i],
                      i, FrequencyCounts_VP3[i]);
  }
}

static int ReadHuffTree(HUFF_ENTRY * HuffRoot, int depth,
                        oggpack_buffer *opb) {
  long bit;
  long ret;
  theora_read(opb,1,&bit);
  if(bit < 0) return OC_BADHEADER;
  else if(!bit) {
    int ret;
    if (++depth > 32) return OC_BADHEADER;
    HuffRoot->ZeroChild = (HUFF_ENTRY *)_ogg_calloc(1, sizeof(HUFF_ENTRY));
    ret = ReadHuffTree(HuffRoot->ZeroChild, depth, opb);
    if (ret < 0) return ret;
    HuffRoot->OneChild = (HUFF_ENTRY *)_ogg_calloc(1, sizeof(HUFF_ENTRY));
    ret = ReadHuffTree(HuffRoot->OneChild, depth, opb);
    if (ret < 0) return ret;
    HuffRoot->Value = -1;
  } else {
    HuffRoot->ZeroChild = NULL;
    HuffRoot->OneChild = NULL;
    theora_read(opb,5,&ret);
    HuffRoot->Value=ret;;
    if (HuffRoot->Value < 0) return OC_BADHEADER;
  }
  return 0;
}

int ReadHuffmanTrees(codec_setup_info *ci, oggpack_buffer *opb) {
  int i;
  for (i=0; i<NUM_HUFF_TABLES; i++) {
     int ret;
     ci->HuffRoot[i] = (HUFF_ENTRY *)_ogg_calloc(1, sizeof(HUFF_ENTRY));
     ret = ReadHuffTree(ci->HuffRoot[i], 0, opb);
     if (ret) return ret;
  }
  return 0;
}

static void WriteHuffTree(HUFF_ENTRY *HuffRoot, oggpack_buffer *opb) {
  if (HuffRoot->Value >= 0) {
    oggpackB_write(opb, 1, 1);
    oggpackB_write(opb, HuffRoot->Value, 5);
  } else {
    oggpackB_write(opb, 0, 1);
    WriteHuffTree(HuffRoot->ZeroChild, opb);
    WriteHuffTree(HuffRoot->OneChild, opb);
  }
}

void WriteHuffmanTrees(HUFF_ENTRY *HuffRoot[NUM_HUFF_TABLES],
                       oggpack_buffer *opb) {
  int i;
  for(i=0; i<NUM_HUFF_TABLES; i++) {
    WriteHuffTree(HuffRoot[i], opb);
  }
}

static HUFF_ENTRY *CopyHuffTree(const HUFF_ENTRY *HuffSrc) {
  if(HuffSrc){
    HUFF_ENTRY *HuffDst;
    HuffDst = (HUFF_ENTRY *)_ogg_calloc(1, sizeof(HUFF_ENTRY));
    HuffDst->Value = HuffSrc->Value;
    if (HuffSrc->Value < 0) {
      HuffDst->ZeroChild = CopyHuffTree(HuffSrc->ZeroChild);
      HuffDst->OneChild = CopyHuffTree(HuffSrc->OneChild);
    }
    return HuffDst;
  }
  return NULL;
}

void InitHuffmanTrees(PB_INSTANCE *pbi, const codec_setup_info *ci) {
  int i;
  pbi->ExtraBitLengths_VP3x = ExtraBitLengths_VP31;
  for(i=0; i<NUM_HUFF_TABLES; i++){
    pbi->HuffRoot_VP3x[i] = CopyHuffTree(ci->HuffRoot[i]);
  }
}

void  ClearHuffmanTrees(HUFF_ENTRY *HuffRoot[NUM_HUFF_TABLES]){
  int i;
  for(i=0; i<NUM_HUFF_TABLES; i++) {
    DestroyHuffTree(HuffRoot[i]);
    HuffRoot[i] = NULL;
  }
}