package org.catacomb.movie.gif;
   
   import org.catacomb.report.E;
   
   
   public final class ByteAccumulator extends Object {
       int iin;
       byte[] ba;
   
      int ipend;
      int npend;
  
      int inxb;
      int iout;
  
      static int[] msk = {0, 1, 3, 7, 15, 31, 63, 127, 255, 511};
  
  
      public ByteAccumulator(int n) {
          ba = new byte[n];
          iin = 0;
      }
  
  
      public ByteAccumulator(byte[] ba) {
          this.ba = ba;
          iout = 0;
          inxb = 0;
      }
  
  
  
      public int getNextWritePosition() {
          return iin;
      }
  
      public void checkDoubleSpace() {
          if (iin > ba.length/2) {
              int n = ba.length;
              byte[] bb = new byte[2*n];
              for (int i = 0; i < n; i++) bb[i] = ba[i];
              ba = bb;
          }
      }
  
  
  
  
      public void trim() {
          byte[] ret = new byte[iin];
          System.arraycopy(ba, 0, ret, 0, ret.length);
          ba = ret;
      }
  
      public byte[] getData() {
          flush();
          trim();
          return ba;
      }
  
  
      public void setByte(int i, byte b) {
          ba[i] = b;
      }
  
      public void setByte(int i, int b) {
          ba[i] = (byte)b;
      }
  
  
  
      public void appendByte(byte b) {
          ba[iin++] = b;
      }
  
      public void appendByte(int i) {
          ba[iin++] = (byte)i;
      }
  
  
      public void appendBytes(byte[] b) {
          System.arraycopy(b, 0, ba, iin, b.length);
          iin += b.length;
      }
  
  
      public void appendBytes(byte[] b, int ioff, int nb) {
          System.arraycopy(b, ioff, ba, iin, nb);
          iin += nb;
      }
  
  
      public void appendString(String s) {
          appendBytes(s.getBytes());
      }
  
  
      public void appendInt2(int i) {
          /*
          byte[] bt = {(byte)((i >> 8) & 0xff),
            (byte) (i & 0xff)};
            */
         byte[] bt = {(byte)((i) & 0xff),
                      (byte)((i >> 8) & 0xff)
                     };
 
 
         appendBytes(bt);
     }
 
     public void appendInt4(int i) {
         byte[] bt = {(byte)((i >> 24) & 0xff),
                      (byte)((i >> 16) & 0xff),
                      (byte)((i >> 8) & 0xff),
                      (byte)(i & 0xff)
                     };
         appendBytes(bt);
 
     }
 
 
     public void append(int i, int p) {
         if (i < 0) {
             E.error("appending negeative no to byte stream");
         }
 
         // append last p bits of i to stream;
         ipend += (i << npend);
         npend += p;
         while (npend >= 8) {
             appendByte(ipend & 0xff);
             ipend = (ipend >> 8);
             npend -= 8;
         }
     }
 
 
     public void flush() {
         if (npend > 0) {
             appendByte(ipend & 0xff);
         }
     }
 
 
     public int nextElt(int p) {
         int ng = 0;
 
         int ir = 0;
 
         while (ng < p) {
             if (iout >= ba.length) {
                 return -1;
             }
 
             int ntk = p - ng;
             if (ntk > 8 - inxb) {
                 ntk = 8 - inxb;
             }
 
             ir += ((ba[iout] >> inxb) & msk[ntk]) << ng;
 
 
             inxb += ntk;
             if (inxb == 8) {
                 iout++;
                 inxb = 0;
             }
             ng += ntk;
         }
 
         return ir;
     }
 
 
 }