code: function forloop (a, sbx) {
  		var step = this._register.getItem(a + 2),
  			limit = this._register.getItem(a + 1),
  			index = this._register.getItem(a) + step,
  			parity = step / Math.abs(step);
  		
  		this._register.setItem(a, index);
  		
  		if ((parity === 1 && index <= limit) || (parity !== 1 && index >= limit)) {
  			this._register.setItem(a + 3, index);
  			this._pc += sbx;
  		}
  	}
docs: *************************************************************** forloop