ALU.hdl

/* 
* An arithmetic logic unit!
* It has 6 input bits; combine them for operations.
*
* x and y represent 16 bit numerical inputs
* nx: negate x
* zx: zero x (set all bits in x to 0)
* ny: negate y
* zy: zero y
* f: if 1, x+y; else x&y
* no: negate output
*/

CHIP ALU {
	IN x[16], y[16], zx, nx, zy, ny, f, no;
	OUT out[16];
	PARTS:
	//zeroing x
	MUX16(a=x, b[0..15]=false, sel=zx, out=outx1);
	//negating x
	NOT16(a=outx1, out=notoutx1);
	MUX16(a=outx1, b=notoutx1, sel=nx, out=outx2);

	//zeroing y
	MUX16(a=y, b[0..15]=false, sel=zy, out=outy1);
	//negating y
	NOT16(a=outy1, out=notouty1);
	MUX16(a=outy1, b=notouty1, sel=ny, out=outy2);

	//f: add or and
	ADDER16(a=outx2, b=outy2, out=adderout);
	AND16(a=outx2, b=outy2, out=andout);
	MUX16(a=andout, b=adderout, sel=f, out=fout);

	//no: negate out or no
	NOT16(a=fout, out=notfout);
	MUX16(a=fout, b=notfout, sel=no, out=out);
}