root / trunk / web / dojo / dojox / encoding / compression / splay.js
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| 1 | 9 | andrej.cim | /*
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| 2 | Copyright (c) 2004-2010, The Dojo Foundation All Rights Reserved.
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| 3 | Available via Academic Free License >= 2.1 OR the modified BSD license.
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| 4 | see: http://dojotoolkit.org/license for details
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| 5 | */
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| 6 | |||
| 7 | |||
| 8 | if(!dojo._hasResource["dojox.encoding.compression.splay"]){ |
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| 9 | dojo._hasResource["dojox.encoding.compression.splay"]=true; |
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| 10 | dojo.provide("dojox.encoding.compression.splay");
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| 11 | dojo.require("dojox.encoding.bits");
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| 12 | dojox.encoding.compression.Splay=function(n){ |
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| 13 | this.up=new Array(2*n+1); |
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| 14 | this.left=new Array(n); |
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| 15 | this.right=new Array(n); |
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| 16 | this.reset();
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| 17 | }; |
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| 18 | dojo.extend(dojox.encoding.compression.Splay,{reset:function(){
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| 19 | for(var i=1;i<this.up.length;this.up[i]=Math.floor((i-1)/2),++i){ |
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| 20 | } |
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| 21 | for(var i=0;i<this.left.length;this.left[i]=2*i+1,this.right[i]=2*i+2,++i){ |
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| 22 | } |
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| 23 | },splay:function(i){ |
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| 24 | var a=i+this.left.length; |
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| 25 | do{
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| 26 | var c=this.up[a]; |
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| 27 | if(c){
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| 28 | var d=this.up[c]; |
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| 29 | var b=this.left[d]; |
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| 30 | if(c==b){
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| 31 | b=this.right[d];
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| 32 | this.right[d]=a;
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| 33 | }else{
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| 34 | this.left[d]=a;
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| 35 | } |
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| 36 | this[a==this.left[c]?"left":"right"][c]=b; |
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| 37 | this.up[a]=d;
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| 38 | this.up[b]=c;
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| 39 | a=d; |
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| 40 | }else{
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| 41 | a=c; |
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| 42 | } |
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| 43 | }while(a);
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| 44 | },encode:function(_1,_2){ |
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| 45 | var s=[],a=_1+this.left.length; |
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| 46 | do{
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| 47 | s.push(this.right[this.up[a]]==a); |
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| 48 | a=this.up[a];
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| 49 | }while(a);
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| 50 | this.splay(_1);
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| 51 | var l=s.length;
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| 52 | while(s.length){
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| 53 | _2.putBits(s.pop()?1:0,1); |
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| 54 | } |
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| 55 | return l;
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| 56 | },decode:function(_3){ |
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| 57 | var a=0; |
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| 58 | do{
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| 59 | a=this[_3.getBits(1)?"right":"left"][a]; |
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| 60 | }while(a<this.left.length); |
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| 61 | a-=this.left.length;
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| 62 | this.splay(a);
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| 63 | return a;
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| 64 | }}); |
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| 65 | } |