nand2tetris Mux8Way16.hdl

Mux8Way16.hdl

// 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/01/Mux8Way16.hdl

/**
 * 8-way 16-bit multiplexor:
 * out = a if sel == 000
 *       b if sel == 001
 *       etc.
 *       h if sel == 111
 */

CHIP Mux8Way16 {
    IN a[16], b[16], c[16], d[16],
       e[16], f[16], g[16], h[16],
       sel[3];
    OUT out[16];

    PARTS:

    // make sel selector
    Not(in=sel[2], out=sel2n);
    Not(in=sel[1], out=sel1n);
    Not(in=sel[0], out=sel0n);

    // 000
    And(a=sel2n, b=sel1n, out=sel000tmp);
    And(a=sel000tmp, b=sel0n, out=sel000);
    And16(a=a, b[0]=sel000, b[1]=sel000, b[2]=sel000, b[3]=sel000, b[4]=sel000, b[5]=sel000, b[6]=sel000, b[7]=sel000, b[8]=sel000, b[9]=sel000, b[10]=sel000, b[11]=sel000, b[12]=sel000, b[13]=sel000, b[14]=sel000, b[15]=sel000, out=aOut);

    // 001
    And(a=sel2n, b=sel1n, out=sel001tmp);
    And(a=sel001tmp, b=sel[0], out=sel001);
    And16(a=b, b[0]=sel001, b[1]=sel001, b[2]=sel001, b[3]=sel001, b[4]=sel001, b[5]=sel001, b[6]=sel001, b[7]=sel001, b[8]=sel001, b[9]=sel001, b[10]=sel001, b[11]=sel001, b[12]=sel001, b[13]=sel001, b[14]=sel001, b[15]=sel001, out=bOut);

    // 010
    And(a=sel2n, b=sel[1], out=sel010tmp);
    And(a=sel010tmp, b=sel0n, out=sel010);
    And16(a=c, b[0]=sel010, b[1]=sel010, b[2]=sel010, b[3]=sel010, b[4]=sel010, b[5]=sel010, b[6]=sel010, b[7]=sel010, b[8]=sel010, b[9]=sel010, b[10]=sel010, b[11]=sel010, b[12]=sel010, b[13]=sel010, b[14]=sel010, b[15]=sel010, out=cOut);

    // 011
    And(a=sel2n, b=sel[1], out=sel011tmp);
    And(a=sel011tmp, b=sel[0], out=sel011);
    And16(a=d, b[0]=sel011, b[1]=sel011, b[2]=sel011, b[3]=sel011, b[4]=sel011, b[5]=sel011, b[6]=sel011, b[7]=sel011, b[8]=sel011, b[9]=sel011, b[10]=sel011, b[11]=sel011, b[12]=sel011, b[13]=sel011, b[14]=sel011, b[15]=sel011, out=dOut);

    ////
    // 100
    And(a=sel[2], b=sel1n, out=sel100tmp);
    And(a=sel100tmp, b=sel0n, out=sel100);
    And16(a=e, b[0]=sel100, b[1]=sel100, b[2]=sel100, b[3]=sel100, b[4]=sel100, b[5]=sel100, b[6]=sel100, b[7]=sel100, b[8]=sel100, b[9]=sel100, b[10]=sel100, b[11]=sel100, b[12]=sel100, b[13]=sel100, b[14]=sel100, b[15]=sel100, out=eOut);

    // 101
    And(a=sel[2], b=sel1n, out=sel101tmp);
    And(a=sel101tmp, b=sel[0], out=sel101);
    And16(a=f, b[0]=sel101, b[1]=sel101, b[2]=sel101, b[3]=sel101, b[4]=sel101, b[5]=sel101, b[6]=sel101, b[7]=sel101, b[8]=sel101, b[9]=sel101, b[10]=sel101, b[11]=sel101, b[12]=sel101, b[13]=sel101, b[14]=sel101, b[15]=sel101, out=fOut);

    // 110
    And(a=sel[2], b=sel[1], out=sel110tmp);
    And(a=sel110tmp, b=sel0n, out=sel110);
    And16(a=g, b[0]=sel110, b[1]=sel110, b[2]=sel110, b[3]=sel110, b[4]=sel110, b[5]=sel110, b[6]=sel110, b[7]=sel110, b[8]=sel110, b[9]=sel110, b[10]=sel110, b[11]=sel110, b[12]=sel110, b[13]=sel110, b[14]=sel110, b[15]=sel110, out=gOut);
    // 111
    And(a=sel[2], b=sel[1], out=sel111tmp);
    And(a=sel111tmp, b=sel[0], out=sel111);
    And16(a=h, b[0]=sel111, b[1]=sel111, b[2]=sel111, b[3]=sel111, b[4]=sel111, b[5]=sel111, b[6]=sel111, b[7]=sel111, b[8]=sel111, b[9]=sel111, b[10]=sel111, b[11]=sel111, b[12]=sel111, b[13]=sel111, b[14]=sel111, b[15]=sel111, out=hOut);

    Or16(a=aOut, b=bOut, out=abOut);
    Or16(a=cOut, b=dOut, out=cdOut);
    Or16(a=eOut, b=fOut, out=efOut);
    Or16(a=gOut, b=hOut, out=ghOut);

    Or16(a=abOut, b=cdOut, out=abcdOut);
    Or16(a=efOut, b=ghOut, out=efghOut);

    Or16(a=abcdOut, b=efghOut, out=out);
}