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StaticCodeBook.java

/* -*-mode:java; c-basic-offset:2; indent-tabs-mode:nil -*- */
/* JOrbis
 * Copyright (C) 2000 ymnk, JCraft,Inc.
 *  
 * Written by: 2000 ymnk<ymnk@jcraft.com>
 *   
 * Many thanks to 
 *   Monty <monty@xiph.org> and 
 *   The XIPHOPHORUS Company http://www.xiph.org/ .
 * JOrbis has been based on their awesome works, Vorbis codec.
 *   
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public License
 * as published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
   
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

package com.jcraft.jorbis;

import com.jcraft.jogg.*;

class StaticCodeBook{
  int dim; // codebook dimensions (elements per vector)
  int entries; // codebook entries
  int[] lengthlist; // codeword lengths in bits

  // mapping
  int maptype; // 0=none
  // 1=implicitly populated values from map column 
  // 2=listed arbitrary values

  // The below does a linear, single monotonic sequence mapping.
  int q_min; // packed 32 bit float; quant value 0 maps to minval
  int q_delta; // packed 32 bit float; val 1 - val 0 == delta
  int q_quant; // bits: 0 < quant <= 16
  int q_sequencep; // bitflag

  // additional information for log (dB) mapping; the linear mapping
  // is assumed to actually be values in dB.  encodebias is used to
  // assign an error weight to 0 dB. We have two additional flags:
  // zeroflag indicates if entry zero is to represent -Inf dB; negflag
  // indicates if we're to represent negative linear values in a
  // mirror of the positive mapping.

  int[] quantlist; // map == 1: (int)(entries/dim) element column map
  // map == 2: list of dim*entries quantized entry vals

  StaticCodeBook(){
  }

  int pack(Buffer opb){
    int i;
    boolean ordered=false;

    opb.write(0x564342, 24);
    opb.write(dim, 16);
    opb.write(entries, 24);

    // pack the codewords.  There are two packings; length ordered and
    // length random.  Decide between the two now.

    for(i=1; i<entries; i++){
      if(lengthlist[i]<lengthlist[i-1])
        break;
    }
    if(i==entries)
      ordered=true;

    if(ordered){
      // length ordered.  We only need to say how many codewords of
      // each length.  The actual codewords are generated
      // deterministically

      int count=0;
      opb.write(1, 1); // ordered
      opb.write(lengthlist[0]-1, 5); // 1 to 32

      for(i=1; i<entries; i++){
        int _this=lengthlist[i];
        int _last=lengthlist[i-1];
        if(_this>_last){
          for(int j=_last; j<_this; j++){
            opb.write(i-count, Util.ilog(entries-count));
            count=i;
          }
        }
      }
      opb.write(i-count, Util.ilog(entries-count));
    }
    else{
      // length random.  Again, we don't code the codeword itself, just
      // the length.  This time, though, we have to encode each length
      opb.write(0, 1); // unordered

      // algortihmic mapping has use for 'unused entries', which we tag
      // here.  The algorithmic mapping happens as usual, but the unused
      // entry has no codeword.
      for(i=0; i<entries; i++){
        if(lengthlist[i]==0)
          break;
      }

      if(i==entries){
        opb.write(0, 1); // no unused entries
        for(i=0; i<entries; i++){
          opb.write(lengthlist[i]-1, 5);
        }
      }
      else{
        opb.write(1, 1); // we have unused entries; thus we tag
        for(i=0; i<entries; i++){
          if(lengthlist[i]==0){
            opb.write(0, 1);
          }
          else{
            opb.write(1, 1);
            opb.write(lengthlist[i]-1, 5);
          }
        }
      }
    }

    // is the entry number the desired return value, or do we have a
    // mapping? If we have a mapping, what type?
    opb.write(maptype, 4);
    switch(maptype){
      case 0:
        // no mapping
        break;
      case 1:
      case 2:
        // implicitly populated value mapping
        // explicitly populated value mapping
        if(quantlist==null){
          // no quantlist?  error
          return (-1);
        }

        // values that define the dequantization
        opb.write(q_min, 32);
        opb.write(q_delta, 32);
        opb.write(q_quant-1, 4);
        opb.write(q_sequencep, 1);

        {
          int quantvals=0;
          switch(maptype){
            case 1:
              // a single column of (c->entries/c->dim) quantized values for
              // building a full value list algorithmically (square lattice)
              quantvals=maptype1_quantvals();
              break;
            case 2:
              // every value (c->entries*c->dim total) specified explicitly
              quantvals=entries*dim;
              break;
          }

          // quantized values
          for(i=0; i<quantvals; i++){
            opb.write(Math.abs(quantlist[i]), q_quant);
          }
        }
        break;
      default:
        // error case; we don't have any other map types now
        return (-1);
    }
    return (0);
  }

  // unpacks a codebook from the packet buffer into the codebook struct,
  // readies the codebook auxiliary structures for decode
  int unpack(Buffer opb){
    int i;
    //memset(s,0,sizeof(static_codebook));

    // make sure alignment is correct
    if(opb.read(24)!=0x564342){
      //    goto _eofout;
      clear();
      return (-1);
    }

    // first the basic parameters
    dim=opb.read(16);
    entries=opb.read(24);
    if(entries==-1){
      //    goto _eofout;
      clear();
      return (-1);
    }

    // codeword ordering.... length ordered or unordered?
    switch(opb.read(1)){
      case 0:
        // unordered
        lengthlist=new int[entries];

        // allocated but unused entries?
        if(opb.read(1)!=0){
          // yes, unused entries

          for(i=0; i<entries; i++){
            if(opb.read(1)!=0){
              int num=opb.read(5);
              if(num==-1){
                //            goto _eofout;
                clear();
                return (-1);
              }
              lengthlist[i]=num+1;
            }
            else{
              lengthlist[i]=0;
            }
          }
        }
        else{
          // all entries used; no tagging
          for(i=0; i<entries; i++){
            int num=opb.read(5);
            if(num==-1){
              //          goto _eofout;
              clear();
              return (-1);
            }
            lengthlist[i]=num+1;
          }
        }
        break;
      case 1:
        // ordered
      {
        int length=opb.read(5)+1;
        lengthlist=new int[entries];

        for(i=0; i<entries;){
          int num=opb.read(Util.ilog(entries-i));
          if(num==-1){
            //          goto _eofout;
            clear();
            return (-1);
          }
          for(int j=0; j<num; j++, i++){
            lengthlist[i]=length;
          }
          length++;
        }
      }
        break;
      default:
        // EOF
        return (-1);
    }

    // Do we have a mapping to unpack?
    switch((maptype=opb.read(4))){
      case 0:
        // no mapping
        break;
      case 1:
      case 2:
        // implicitly populated value mapping
        // explicitly populated value mapping
        q_min=opb.read(32);
        q_delta=opb.read(32);
        q_quant=opb.read(4)+1;
        q_sequencep=opb.read(1);

        {
          int quantvals=0;
          switch(maptype){
            case 1:
              quantvals=maptype1_quantvals();
              break;
            case 2:
              quantvals=entries*dim;
              break;
          }

          // quantized values
          quantlist=new int[quantvals];
          for(i=0; i<quantvals; i++){
            quantlist[i]=opb.read(q_quant);
          }
          if(quantlist[quantvals-1]==-1){
            //        goto _eofout;
            clear();
            return (-1);
          }
        }
        break;
      default:
        //    goto _eofout;
        clear();
        return (-1);
    }
    // all set
    return (0);
    //    _errout:
    //    _eofout:
    //    vorbis_staticbook_clear(s);
    //    return(-1); 
  }

  // there might be a straightforward one-line way to do the below
  // that's portable and totally safe against roundoff, but I haven't
  // thought of it.  Therefore, we opt on the side of caution
  private int maptype1_quantvals(){
    int vals=(int)(Math.floor(Math.pow(entries, 1./dim)));

    // the above *should* be reliable, but we'll not assume that FP is
    // ever reliable when bitstream sync is at stake; verify via integer
    // means that vals really is the greatest value of dim for which
    // vals^b->bim <= b->entries
    // treat the above as an initial guess
    while(true){
      int acc=1;
      int acc1=1;
      for(int i=0; i<dim; i++){
        acc*=vals;
        acc1*=vals+1;
      }
      if(acc<=entries&&acc1>entries){
        return (vals);
      }
      else{
        if(acc>entries){
          vals--;
        }
        else{
          vals++;
        }
      }
    }
  }

  void clear(){
  }

  // unpack the quantized list of values for encode/decode
  // we need to deal with two map types: in map type 1, the values are
  // generated algorithmically (each column of the vector counts through
  // the values in the quant vector). in map type 2, all the values came
  // in in an explicit list.  Both value lists must be unpacked
  float[] unquantize(){

    if(maptype==1||maptype==2){
      int quantvals;
      float mindel=float32_unpack(q_min);
      float delta=float32_unpack(q_delta);
      float[] r=new float[entries*dim];

      // maptype 1 and 2 both use a quantized value vector, but
      // different sizes
      switch(maptype){
        case 1:
          // most of the time, entries%dimensions == 0, but we need to be
          // well defined.  We define that the possible vales at each
          // scalar is values == entries/dim.  If entries%dim != 0, we'll
          // have 'too few' values (values*dim<entries), which means that
          // we'll have 'left over' entries; left over entries use zeroed
          // values (and are wasted).  So don't generate codebooks like that
          quantvals=maptype1_quantvals();
          for(int j=0; j<entries; j++){
            float last=0.f;
            int indexdiv=1;
            for(int k=0; k<dim; k++){
              int index=(j/indexdiv)%quantvals;
              float val=quantlist[index];
              val=Math.abs(val)*delta+mindel+last;
              if(q_sequencep!=0)
                last=val;
              r[j*dim+k]=val;
              indexdiv*=quantvals;
            }
          }
          break;
        case 2:
          for(int j=0; j<entries; j++){
            float last=0.f;
            for(int k=0; k<dim; k++){
              float val=quantlist[j*dim+k];
              //if((j*dim+k)==0){System.err.println(" | 0 -> "+val+" | ");}
              val=Math.abs(val)*delta+mindel+last;
              if(q_sequencep!=0)
                last=val;
              r[j*dim+k]=val;
              //if((j*dim+k)==0){System.err.println(" $ r[0] -> "+r[0]+" | ");}
            }
          }
          //System.err.println("\nr[0]="+r[0]);
      }
      return (r);
    }
    return (null);
  }

  // 32 bit float (not IEEE; nonnormalized mantissa +
  // biased exponent) : neeeeeee eeemmmmm mmmmmmmm mmmmmmmm 
  // Why not IEEE?  It's just not that important here.

  static final int VQ_FEXP=10;
  static final int VQ_FMAN=21;
  static final int VQ_FEXP_BIAS=768; // bias toward values smaller than 1.

  // doesn't currently guard under/overflow 
  static long float32_pack(float val){
    int sign=0;
    int exp;
    int mant;
    if(val<0){
      sign=0x80000000;
      val=-val;
    }
    exp=(int)Math.floor(Math.log(val)/Math.log(2));
    mant=(int)Math.rint(Math.pow(val, (VQ_FMAN-1)-exp));
    exp=(exp+VQ_FEXP_BIAS)<<VQ_FMAN;
    return (sign|exp|mant);
  }

  static float float32_unpack(int val){
    float mant=val&0x1fffff;
    float exp=(val&0x7fe00000)>>>VQ_FMAN;
    if((val&0x80000000)!=0)
      mant=-mant;
    return (ldexp(mant, ((int)exp)-(VQ_FMAN-1)-VQ_FEXP_BIAS));
  }

  static float ldexp(float foo, int e){
    return (float)(foo*Math.pow(2, e));
  }
}

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