Constellations/js/Share/Encoder.js

function Encoder() {
	this.buffer = '';
	this.stack = 0;
	this.size = 0;
}

Encoder.prototype.push = function(one) {
	if(this.size > 7) {
		this.flush();
	}
	this.stack = 2*this.stack + (one ? 1 : 0);
	this.size++;
};

Encoder.prototype.flush = function() {
	this.buffer = this.buffer + String.fromCharCode(this.stack);
	this.stack = 0;
	this.size = 0;
};

Encoder.prototype.output = function() {
	while(this.size < 8) {
		this.push(0);
	}
	this.flush();
	return btoa(this.buffer);
};

Encoder.prototype.variableLength3 = function(n) {
	if(n > 0) {
		this.push(1);
	}
	this.push(n > 1);
};

Encoder.prototype.variableLength6 = function(n) {
	if(n > 1) {
		this.push(1);
	}
	this.push(n > 3);
	this.push(n % 2);
};

Encoder.prototype.int = function(size) {
	var encoder = this;
	return function(n) {
		for(var i = 0; i < size; i++) {
			encoder.push(n > 3);
			n = (2*n) & 7;
		}
	}
};

return {
	make: function() {return new Encoder();}
};