Built the ALU and tested as working.

2021-02-12 17:00:52 -06:00
parent e0703c9f60
commit 731818ea92
2 changed files with 60 additions and 1 deletions
@@ -42,5 +42,27 @@ CHIP ALU {
        ng; // 1 if (out < 0),  0 otherwise

    PARTS:
-   // Put you code here:
+	// Zero out X / Y?
+    Mux16(a=x, b=false, sel=zx, out=x1);
+	Mux16(a=y, b=false, sel=zy, out=y1);
+	
+	// Handle negating the input
+	Not16(in=x1, out=negatedX);
+	Mux16(a=x1, b=negatedX, sel=nx, out=x2);
+	Not16(in=y1, out=negatedY);
+	Mux16(a=y1, b=negatedY, sel=ny, out=y2);
+	
+	// 2's compliment
+	And16(a=x2, b=y2, out=xAndy);
+	Add16(a=x2, b=y2, out=xPlusy);
+	Mux16(a=xAndy, b=xPlusy, sel=f, out=xy);
+	
+	// Negate
+	Not16(in=xy, out=notXY);
+	Mux16(a=xy, b=notXY, sel=no, out[15]=ng, out[8..15]=msb, out[0..7]=lsb, out=out);
+	// Is zero?
+	Or8Way(in=msb, out=msbResult);
+	Or8Way(in=lsb, out=lsbResult);
+	Or(a=msbResult, b=lsbResult, out=result);
+	Not(in=result, out=zr);
 }