1/*
 2    Copyright 2018 0KIMS association.
 3
 4    This file is part of circom (Zero Knowledge Circuit Compiler).
 5
 6    circom is a free software: you can redistribute it and/or modify it
 7    under the terms of the GNU General Public License as published by
 8    the Free Software Foundation, either version 3 of the License, or
 9    (at your option) any later version.
10
11    circom is distributed in the hope that it will be useful, but WITHOUT
12    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13    or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14    License for more details.
15
16    You should have received a copy of the GNU General Public License
17    along with circom. If not, see <https://www.gnu.org/licenses/>.
18*/
19pragma circom 2.0.0;
20
21include "bitify.circom";
22
23// Returns 1 if in (in binary) > ct
24
25template CompConstant(ct) {
26    signal input in[254];
27    signal output out;
28
29    signal parts[127];
30    signal sout;
31
32    var clsb;
33    var cmsb;
34    var slsb;
35    var smsb;
36
37    var sum=0;
38
39    var b = (1 << 128) -1;
40    var a = 1;
41    var e = 1;
42    var i;
43
44    for (i=0;i<127; i++) {
45        clsb = (ct >> (i*2)) & 1;
46        cmsb = (ct >> (i*2+1)) & 1;
47        slsb = in[i*2];
48        smsb = in[i*2+1];
49
50        if ((cmsb==0)&&(clsb==0)) {
51            parts[i] <== -b*smsb*slsb + b*smsb + b*slsb;
52        } else if ((cmsb==0)&&(clsb==1)) {
53            parts[i] <== a*smsb*slsb - a*slsb + b*smsb - a*smsb + a;
54        } else if ((cmsb==1)&&(clsb==0)) {
55            parts[i] <== b*smsb*slsb - a*smsb + a;
56        } else {
57            parts[i] <== -a*smsb*slsb + a;
58        }
59
60        sum = sum + parts[i];
61
62        b = b -e;
63        a = a +e;
64        e = e*2;
65    }
66
67    sout <== sum;
68
69    component num2bits = Num2Bits(135);
70
71    num2bits.in <== sout;
72
73    out <== num2bits.out[127];
74}