source: Dev/trunk/src/client/dojox/encoding/bits.js @ 536

define([
        "dojo/_base/lang"       // dojo.extend
], function(lang) {
        var bits = lang.getObject("dojox.encoding.bits", true);

        bits.OutputStream = function(){
                this.reset();
        };

        lang.extend(bits.OutputStream, {
                reset: function(){
                        this.buffer = [];
                        this.accumulator = 0;
                        this.available = 8;
                },
                putBits: function(value, width){
                        while(width){
                                var w = Math.min(width, this.available);
                                var v = (w <= width ? value >>> (width - w) : value) << (this.available - w);
                                this.accumulator |= v & (255 >>> (8 - this.available));
                                this.available -= w;
                                if(!this.available){
                                        this.buffer.push(this.accumulator);
                                        this.accumulator = 0;
                                        this.available = 8;
                                }
                                width -= w;
                        }
                },
                getWidth: function(){
                        return this.buffer.length * 8 + (8 - this.available);
                },
                getBuffer: function(){
                        var b = this.buffer;
                        if(this.available < 8){ b.push(this.accumulator & (255 << this.available)); }
                        this.reset();
                        return b;
                }
        });

        bits.InputStream = function(buffer, width){
                this.buffer = buffer;
                this.width = width;
                this.bbyte = this.bit = 0;
        };

        lang.extend(bits.InputStream, {
                getBits: function(width){
                        var r = 0;
                        while(width){
                                var w = Math.min(width, 8 - this.bit);
                                var v = this.buffer[this.bbyte] >>> (8 - this.bit - w);
                                r <<= w;
                                r |= v & ~(~0 << w);
                                this.bit += w;
                                if(this.bit == 8){
                                        ++this.bbyte;
                                        this.bit = 0;
                                }
                                width -= w;
                        }
                        return r;
                },
                getWidth: function(){
                        return this.width - this.bbyte * 8 - this.bit;
                }
        });


        return bits;
});