75 lines
1.4 KiB
JavaScript
75 lines
1.4 KiB
JavaScript
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//>>built
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define("dojox/encoding/compression/lzw",["dojo/_base/lang","../bits"],function(_1,_2){
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var _3=_1.getObject("dojox.encoding.compression.lzw",true);
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var _4=function(x){
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var w=1;
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for(var v=2;x>=v;v<<=1,++w){
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}
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return w;
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};
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_3.Encoder=function(n){
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this.size=n;
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this.init();
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};
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_1.extend(_3.Encoder,{init:function(){
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this.dict={};
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for(var i=0;i<this.size;++i){
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this.dict[String.fromCharCode(i)]=i;
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}
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this.width=_4(this.code=this.size);
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this.p="";
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},encode:function(_5,_6){
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var c=String.fromCharCode(_5),p=this.p+c,r=0;
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if(p in this.dict){
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this.p=p;
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return r;
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}
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_6.putBits(this.dict[this.p],this.width);
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if((this.code&(this.code+1))==0){
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_6.putBits(this.code++,r=this.width++);
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}
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this.dict[p]=this.code++;
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this.p=c;
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return r+this.width;
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},flush:function(_7){
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if(this.p.length==0){
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return 0;
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}
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_7.putBits(this.dict[this.p],this.width);
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this.p="";
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return this.width;
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}});
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_3.Decoder=function(n){
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this.size=n;
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this.init();
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};
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_1.extend(_3.Decoder,{init:function(){
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this.codes=new Array(this.size);
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for(var i=0;i<this.size;++i){
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this.codes[i]=String.fromCharCode(i);
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}
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this.width=_4(this.size);
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this.p=-1;
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},decode:function(_8){
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var c=_8.getBits(this.width),v;
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if(c<this.codes.length){
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v=this.codes[c];
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if(this.p>=0){
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this.codes.push(this.codes[this.p]+v.substr(0,1));
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}
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}else{
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if((c&(c+1))==0){
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this.codes.push("");
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++this.width;
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return "";
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}
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var x=this.codes[this.p];
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v=x+x.substr(0,1);
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this.codes.push(v);
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}
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this.p=c;
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return v;
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}});
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return _3;
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});
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