1  const path = require("path");
 2  const F1Field = require("ffjavascript").F1Field;
 3  const Scalar = require("ffjavascript").Scalar;
 4  exports.p = Scalar.fromString("21888242871839275222246405745257275088548364400416034343698204186575808495617");
 5  const Fr = new F1Field(exports.p);
 6  const wasm_tester = require("circom_tester").wasm;
 7  
 8  function print(circuit, w, s) {
 9      console.log(s + ": " + w[circuit.getSignalIdx(s)]);
10  }
11  
12  function getBits(v, n) {
13      const res = [];
14      for (let i=0; i<n; i++) {
15          if (Scalar.isOdd(Scalar.shr(v, i))) {
16              res.push(Fr.one);
17          } else {
18              res.push(Fr.zero);
19          }
20      }
21      return res;
22  }
23  
24  const q = Scalar.fromString("21888242871839275222246405745257275088548364400416034343698204186575808495617");
25  
26  describe("Sign test", function() {
27      let circuit;
28      this.timeout(100000);
29  
30      before( async() => {
31          circuit = await wasm_tester(path.join(__dirname, "circuits", "sign_test.circom"));
32      });
33  
34      it("Sign of 0", async () => {
35          const inp = getBits(Scalar.e(0), 254);
36          const w = await circuit.calculateWitness({in: inp}, true);
37  
38          await circuit.assertOut(w, {sign: 0});
39      });
40  
41      it("Sign of 3", async () => {
42          const inp = getBits(Scalar.e(3), 254);
43          const w = await circuit.calculateWitness({in: inp}, true);
44  
45          await circuit.assertOut(w, {sign: 0});
46      });
47  
48      it("Sign of q/2", async () => {
49          const inp = getBits(Scalar.shr(q, 1), 254);
50          const w = await circuit.calculateWitness({in: inp}, true);
51  
52          await circuit.assertOut(w, {sign: 0});
53      });
54  
55      it("Sign of q/2+1", async () => {
56          const inp = getBits(Scalar.add(Scalar.shr(q, 1), 1) , 254);
57          const w = await circuit.calculateWitness({in: inp}, true);
58  
59          await circuit.assertOut(w, {sign: 1});
60      });
61  
62      it("Sign of q-1", async () => {
63          const inp = getBits(Scalar.sub(q, 1), 254);
64          const w = await circuit.calculateWitness({in: inp}, true);
65  
66          await circuit.assertOut(w, {sign: 1});
67      });
68  
69      it("Sign of q", async () => {
70          const inp = getBits(q, 254);
71          const w = await circuit.calculateWitness({in: inp}, true);
72  
73          await circuit.assertOut(w, {sign: 1});
74      });
75  
76      it("Sign of all ones", async () => {
77          const inp = getBits(Scalar.sub(Scalar.shl(1,254),1), 254);
78          const w = await circuit.calculateWitness({in: inp}, true);
79  
80          await circuit.assertOut(w, {sign: 1});
81      });
82  });