git.pond.sub.org Git - eow/blob - static/dojo-release-1.1.1/dojox/encoding/bits.js

   1 if(!dojo._hasResource["dojox.encoding.bits"]){ //_hasResource checks added by build. Do not use _hasResource directly in your code.
   2 dojo._hasResource["dojox.encoding.bits"] = true;
   3 dojo.provide("dojox.encoding.bits");
   4
   5 dojox.encoding.bits.OutputStream = function(){
   6         this.reset();
   7 };
   8
   9 dojo.extend(dojox.encoding.bits.OutputStream, {
  10         reset: function(){
  11                 this.buffer = [];
  12                 this.accumulator = 0;
  13                 this.available = 8;
  14         },
  15         putBits: function(value, width){
  16                 while(width){
  17                         var w = Math.min(width, this.available);
  18                         var v = (w <= width ? value >>> (width - w) : value) << (this.available - w);
  19                         this.accumulator |= v & (255 >>> (8 - this.available));
  20                         this.available -= w;
  21                         if(!this.available){
  22                                 this.buffer.push(this.accumulator);
  23                                 this.accumulator = 0;
  24                                 this.available = 8;
  25                         }
  26                         width -= w;
  27                 }
  28         },
  29         getWidth: function(){
  30                 return this.buffer.length * 8 + (8 - this.available);
  31         },
  32         getBuffer: function(){
  33                 var b = this.buffer;
  34                 if(this.available < 8){ b.push(this.accumulator & (255 << this.available)); }
  35                 this.reset();
  36                 return b;
  37         }
  38 });
  39
  40 dojox.encoding.bits.InputStream = function(buffer, width){
  41         this.buffer = buffer;
  42         this.width = width;
  43         this.bbyte = this.bit = 0;
  44 };
  45
  46 dojo.extend(dojox.encoding.bits.InputStream, {
  47         getBits: function(width){
  48                 var r = 0;
  49                 while(width){
  50                         var w = Math.min(width, 8 - this.bit);
  51                         var v = this.buffer[this.bbyte] >>> (8 - this.bit - w);
  52                         r <<= w;
  53                         r |= v & ~(~0 << w);
  54                         this.bit += w;
  55                         if(this.bit == 8){
  56                                 ++this.bbyte;
  57                                 this.bit = 0;
  58                         }
  59                         width -= w;
  60                 }
  61                 return r;
  62         },
  63         getWidth: function(){
  64                 return this.width - this.bbyte * 8 - this.bit;
  65         }
  66 });
  67
  68 }