56 lines
928 B
JavaScript
56 lines
928 B
JavaScript
function Encoder() {
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this.buffer = '';
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this.stack = 0;
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this.size = 0;
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}
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Encoder.prototype.push = function(one) {
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if(this.size > 7) {
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this.flush();
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}
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this.stack = 2*this.stack + (one ? 1 : 0);
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this.size++;
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};
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Encoder.prototype.flush = function() {
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this.buffer = this.buffer + String.fromCharCode(this.stack);
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this.stack = 0;
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this.size = 0;
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};
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Encoder.prototype.output = function() {
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while(this.size < 8) {
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this.push(0);
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}
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this.flush();
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return btoa(this.buffer);
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};
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Encoder.prototype.variableLength3 = function(n) {
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if(n > 0) {
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this.push(1);
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}
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this.push(n > 1);
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};
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Encoder.prototype.variableLength6 = function(n) {
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if(n > 1) {
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this.push(1);
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}
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this.push(n > 3);
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this.push(n % 2);
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};
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Encoder.prototype.int = function(size) {
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return function(n) {
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for(var i = 0; i < size; i++) {
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this.push(n > 3);
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n = (2*n) & 7;
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}
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}.bind(this);
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};
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return {
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make: function() {return new Encoder();}
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};
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