// This file is part of www.nand2tetris.org

// and the book "The Elements of Computing Systems"

// by Nisan and Schocken, MIT Press.

// File name: projects/03/a/PC.hdl



/**

 * 16-bit counter with load and reset controls.

 *

 * If reset(t-1) then out(t) = 0

 *    else if load(t-1) then out(t) = in(t-1)

 *         else if inc(t-1) then out(t) = out(t-1) + 1 (integer addition)

 *              else out(t) = out(t-1)

 */



CHIP PC {

    IN in[16],load,inc,reset;

    OUT out[16];



    PARTS:

    Inc16(in=outReg,out=outInc);

    Mux16(a=outReg,b=outInc,sel=inc,out=doneInc);

    Mux16(a=doneInc,b=in,sel=load,out=loadOut);

    Mux16(a=loadOut,b=false,sel=reset,out=outRes);

    Register(in=outRes,load=true,out=outReg,out=out);

}