Mux4Way16

4對16 Mux，a,b,c,d 4組資料線(一組16條)，3條選擇線，16條輸出線。

   |        a         |        b         |        c         |        d         | sel  |       out        |
   | 0000000000000000 | 0000000000000000 | 0000000000000000 | 0000000000000000 |  00  | 0000000000000000 |
   | 0000000000000000 | 0000000000000000 | 0000000000000000 | 0000000000000000 |  01  | 0000000000000000 |
   | 0000000000000000 | 0000000000000000 | 0000000000000000 | 0000000000000000 |  10  | 0000000000000000 |
   | 0000000000000000 | 0000000000000000 | 0000000000000000 | 0000000000000000 |  11  | 0000000000000000 |
   | 0001001000110100 | 1001100001110110 | 1010101010101010 | 0101010101010101 |  00  | 0001001000110100 |
   | 0001001000110100 | 1001100001110110 | 1010101010101010 | 0101010101010101 |  01  | 1001100001110110 |
   | 0001001000110100 | 1001100001110110 | 1010101010101010 | 0101010101010101 |  10  | 1010101010101010 |
   | 0001001000110100 | 1001100001110110 | 1010101010101010 | 0101010101010101 |  11  | 0101010101010101 |

   /**
     * 4-way 16-bit multiplexor:
     * out = a if sel == 00
     *       b if sel == 01
     *       c if sel == 10
     *       d if sel == 11
     */

CHIP Mux4Way16 
       {
              IN a[16], b[16], c[16], d[16], sel[2];
              OUT out[16];

              PARTS:
              Mux16(a=a, b=b, sel=sel[0], out=outab);
              Mux16(a=c, b=d, sel=sel[0], out=outcd);
              Mux16(a=outab, b=outcd, sel=sel[1], out=out);
        }