src/main/java/eu/svjatoslav/imagesqueeze/codec/BitOutputStream.java

   1 package eu.svjatoslav.imagesqueeze.codec;
   2
   3 /**
   4  * Write individual bits to the output stream.
   5  */
   6
   7 import java.io.IOException;
   8 import java.io.OutputStream;
   9
  10 public class BitOutputStream {
  11
  12         int currentByte;
  13         int currentBytePointer;
  14
  15         OutputStream outputStream;
  16
  17         public BitOutputStream(OutputStream outputStream){
  18                 currentByte = 0;
  19                 currentBytePointer = 0;
  20                 this.outputStream = outputStream;
  21         };
  22
  23
  24         public void storeBits(int data, int bitCount) throws IOException {
  25                 for (int i=bitCount-1; i >= 0; i--){
  26
  27                         int mask = 1;
  28                         mask = mask << i;
  29
  30                         int currentBit = data & mask;
  31                         currentByte = currentByte << 1;
  32
  33                         if (currentBit != 0){
  34                                 currentByte = currentByte | 1;
  35                         }
  36                         currentBytePointer++;
  37
  38                         if (currentBytePointer == 8){
  39                                 currentBytePointer = 0;
  40                                 outputStream.write(currentByte);
  41                                 currentByte = 0;
  42                         }
  43                 }
  44         }
  45
  46         public void storeIntegerCompressed8(int data) throws IOException{
  47                 if (data < 256){
  48                         storeBits(0, 1);
  49                         storeBits(data, 8);
  50                 } else {
  51                         storeBits(1, 1);
  52                         storeBits(data, 32);
  53                 }
  54         }
  55
  56         public void finishByte() throws IOException {
  57                 if (currentBytePointer != 0){
  58                         outputStream.write(currentByte);
  59                         currentBytePointer = 0;
  60                 }
  61         }
  62
  63 }