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Buffer.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.jogg;

public class Buffer{
  private static final int BUFFER_INCREMENT=256;

  private static final int[] mask= {0x00000000, 0x00000001, 0x00000003,
      0x00000007, 0x0000000f, 0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff,
      0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff, 0x00001fff, 0x00003fff,
      0x00007fff, 0x0000ffff, 0x0001ffff, 0x0003ffff, 0x0007ffff, 0x000fffff,
      0x001fffff, 0x003fffff, 0x007fffff, 0x00ffffff, 0x01ffffff, 0x03ffffff,
      0x07ffffff, 0x0fffffff, 0x1fffffff, 0x3fffffff, 0x7fffffff, 0xffffffff};

  int ptr=0;
  byte[] buffer=null;
  int endbit=0;
  int endbyte=0;
  int storage=0;

  public void writeinit(){
    buffer=new byte[BUFFER_INCREMENT];
    ptr=0;
    buffer[0]=(byte)'\0';
    storage=BUFFER_INCREMENT;
  }

  public void write(byte[] s){
    for(int i=0; i<s.length; i++){
      if(s[i]==0)
        break;
      write(s[i], 8);
    }
  }

  public void read(byte[] s, int bytes){
    int i=0;
    while(bytes--!=0){
      s[i++]=(byte)(read(8));
    }
  }

  void reset(){
    ptr=0;
    buffer[0]=(byte)'\0';
    endbit=endbyte=0;
  }

  public void writeclear(){
    buffer=null;
  }

  public void readinit(byte[] buf, int bytes){
    readinit(buf, 0, bytes);
  }

  public void readinit(byte[] buf, int start, int bytes){
    ptr=start;
    buffer=buf;
    endbit=endbyte=0;
    storage=bytes;
  }

  public void write(int value, int bits){
    if(endbyte+4>=storage){
      byte[] foo=new byte[storage+BUFFER_INCREMENT];
      System.arraycopy(buffer, 0, foo, 0, storage);
      buffer=foo;
      storage+=BUFFER_INCREMENT;
    }

    value&=mask[bits];
    bits+=endbit;
    buffer[ptr]|=(byte)(value<<endbit);

    if(bits>=8){
      buffer[ptr+1]=(byte)(value>>>(8-endbit));
      if(bits>=16){
        buffer[ptr+2]=(byte)(value>>>(16-endbit));
        if(bits>=24){
          buffer[ptr+3]=(byte)(value>>>(24-endbit));
          if(bits>=32){
            if(endbit>0)
              buffer[ptr+4]=(byte)(value>>>(32-endbit));
            else
              buffer[ptr+4]=0;
          }
        }
      }
    }

    endbyte+=bits/8;
    ptr+=bits/8;
    endbit=bits&7;
  }

  public int look(int bits){
    int ret;
    int m=mask[bits];

    bits+=endbit;

    if(endbyte+4>=storage){
      if(endbyte+(bits-1)/8>=storage)
        return (-1);
    }

    ret=((buffer[ptr])&0xff)>>>endbit;
    if(bits>8){
      ret|=((buffer[ptr+1])&0xff)<<(8-endbit);
      if(bits>16){
        ret|=((buffer[ptr+2])&0xff)<<(16-endbit);
        if(bits>24){
          ret|=((buffer[ptr+3])&0xff)<<(24-endbit);
          if(bits>32&&endbit!=0){
            ret|=((buffer[ptr+4])&0xff)<<(32-endbit);
          }
        }
      }
    }
    return (m&ret);
  }

  public int look1(){
    if(endbyte>=storage)
      return (-1);
    return ((buffer[ptr]>>endbit)&1);
  }

  public void adv(int bits){
    bits+=endbit;
    ptr+=bits/8;
    endbyte+=bits/8;
    endbit=bits&7;
  }

  public void adv1(){
    ++endbit;
    if(endbit>7){
      endbit=0;
      ptr++;
      endbyte++;
    }
  }

  public int read(int bits){
    int ret;
    int m=mask[bits];

    bits+=endbit;

    if(endbyte+4>=storage){
      ret=-1;
      if(endbyte+(bits-1)/8>=storage){
        ptr+=bits/8;
        endbyte+=bits/8;
        endbit=bits&7;
        return (ret);
      }
    }

    ret=((buffer[ptr])&0xff)>>>endbit;
    if(bits>8){
      ret|=((buffer[ptr+1])&0xff)<<(8-endbit);
      if(bits>16){
        ret|=((buffer[ptr+2])&0xff)<<(16-endbit);
        if(bits>24){
          ret|=((buffer[ptr+3])&0xff)<<(24-endbit);
          if(bits>32&&endbit!=0){
            ret|=((buffer[ptr+4])&0xff)<<(32-endbit);
          }
        }
      }
    }

    ret&=m;

    ptr+=bits/8;
    endbyte+=bits/8;
    endbit=bits&7;
    return (ret);
  }

  public int readB(int bits){
    int ret;
    int m=32-bits;

    bits+=endbit;

    if(endbyte+4>=storage){
      /* not the main path */
      ret=-1;
      if(endbyte*8+bits>storage*8){
        ptr+=bits/8;
        endbyte+=bits/8;
        endbit=bits&7;
        return (ret);
      }
    }

    ret=(buffer[ptr]&0xff)<<(24+endbit);
    if(bits>8){
      ret|=(buffer[ptr+1]&0xff)<<(16+endbit);
      if(bits>16){
        ret|=(buffer[ptr+2]&0xff)<<(8+endbit);
        if(bits>24){
          ret|=(buffer[ptr+3]&0xff)<<(endbit);
          if(bits>32&&(endbit!=0))
            ret|=(buffer[ptr+4]&0xff)>>(8-endbit);
        }
      }
    }
    ret=(ret>>>(m>>1))>>>((m+1)>>1);

    ptr+=bits/8;
    endbyte+=bits/8;
    endbit=bits&7;
    return (ret);
  }

  public int read1(){
    int ret;
    if(endbyte>=storage){
      ret=-1;
      endbit++;
      if(endbit>7){
        endbit=0;
        ptr++;
        endbyte++;
      }
      return (ret);
    }

    ret=(buffer[ptr]>>endbit)&1;

    endbit++;
    if(endbit>7){
      endbit=0;
      ptr++;
      endbyte++;
    }
    return (ret);
  }

  public int bytes(){
    return (endbyte+(endbit+7)/8);
  }

  public int bits(){
    return (endbyte*8+endbit);
  }

  public byte[] buffer(){
    return (buffer);
  }

  public static int ilog(int v){
    int ret=0;
    while(v>0){
      ret++;
      v>>>=1;
    }
    return (ret);
  }

  public static void report(String in){
    System.err.println(in);
    System.exit(1);
  }
}

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