1template MultiMux3(n) {
 2    signal input c[n][8];  // Constants
 3    signal input s[3];   // Selector
 4    signal output out[n];
 5
 6    signal a210[n];
 7    signal a21[n];
 8    signal a20[n];
 9    signal a2[n];
10
11    signal a10[n];
12    signal a1[n];
13    signal a0[n];
14    signal a[n];
15
16    // 4 constrains for the intermediary variables
17    signal  s10;
18    s10 <== s[1] * s[0];
19
20    for (var i=0; i<n; i++) {
21
22         a210[i] <==  ( c[i][ 7]-c[i][ 6]-c[i][ 5]+c[i][ 4] - c[i][ 3]+c[i][ 2]+c[i][ 1]-c[i][ 0] ) * s10;
23          a21[i] <==  ( c[i][ 6]-c[i][ 4]-c[i][ 2]+c[i][ 0] ) * s[1];
24          a20[i] <==  ( c[i][ 5]-c[i][ 4]-c[i][ 1]+c[i][ 0] ) * s[0];
25           a2[i] <==  ( c[i][ 4]-c[i][ 0] );
26
27          a10[i] <==  ( c[i][ 3]-c[i][ 2]-c[i][ 1]+c[i][ 0] ) * s10;
28           a1[i] <==  ( c[i][ 2]-c[i][ 0] ) * s[1];
29           a0[i] <==  ( c[i][ 1]-c[i][ 0] ) * s[0];
30            a[i] <==  ( c[i][ 0] )
31
32          out[i] <== ( a210[i] + a21[i] + a20[i] + a2[i] ) * s[2] +
33                     (  a10[i] +  a1[i] +  a0[i] +  a[i] );
34
35    }
36}
37
38template Mux3() {
39    var i;
40    signal input c[8];  // Constants
41    signal input s[3];   // Selector
42    signal output out;
43
44    component mux = MultiMux3(1);
45
46    for (i=0; i<8; i++) {
47        mux.c[0][i] <== c[i];
48    }
49
50    for (i=0; i<3; i++) {
51      s[i] ==> mux.s[i];
52    }
53
54    mux.out[0] ==> out;
55}