Implement is zero nondet hint + test

pkg/hints/hint_codes/secp_hint_codes.go

@@ -39,3 +39,5 @@ assert r == 0, f"verify_zero: Invalid input {ids.val.d0, ids.val.d1, ids.val.d2}
 ids.q = q % PRIME`
 
 const BIGINT_TO_UINT256 = "ids.low = (ids.x.d0 + ids.x.d1 * ids.BASE) & ((1 << 128) - 1)"
+
+const IS_ZERO_NONDET = "memory[ap] = to_felt_or_relocatable(x == 0)"

pkg/hints/hint_processor.go

@@ -223,6 +223,8 @@ func (p *CairoVmHintProcessor) ExecuteHint(vm *vm.VirtualMachine, hintData *any,
 		return verifyZero(data.Ids, vm, execScopes, hint_utils.SECP_P_V2())
 	case BIGINT_TO_UINT256:
 		return bigintToUint256(data.Ids, vm, constants)
+	case IS_ZERO_NONDET:
+		return isZeroNondet(data.Ids, vm)
 	default:
 		return errors.Errorf("Unknown Hint: %s", data.Code)
 	}

pkg/hints/secp_hints.go

@@ -82,3 +82,14 @@ func bigintToUint256(ids IdsManager, vm *VirtualMachine, constants *map[string]l
 	low := xD0.Add(xD1.Mul(base)).And((lambdaworks.FeltOne().Shl(128)).Sub(lambdaworks.FeltOne()))
 	return ids.Insert("low", memory.NewMaybeRelocatableFelt(low), vm)
 }
+
+func isZeroNondet(ids IdsManager, vm *VirtualMachine) error {
+	x, err := ids.GetFelt("x", vm)
+	if err != nil {
+		return err
+	}
+	if x.IsZero() {
+		return vm.Segments.Memory.Insert(vm.RunContext.Ap, memory.NewMaybeRelocatableFelt(lambdaworks.FeltOne()))
+	}
+	return vm.Segments.Memory.Insert(vm.RunContext.Ap, memory.NewMaybeRelocatableFelt(lambdaworks.FeltZero()))
+}

pkg/hints/secp_hints_test.go

@@ -250,3 +250,65 @@ func TestBigIntTo256(t *testing.T) {
 		t.Error("Wrong/No ids.low")
 	}
 }
+
+func TestIsZeroTrue(t *testing.T) {
+	vm := NewVirtualMachine()
+	vm.Segments.AddSegment()
+	idsManager := SetupIdsForTest(
+		map[string][]*MaybeRelocatable{
+			"x": {
+				NewMaybeRelocatableFelt(FeltZero()),
+			},
+		},
+		vm,
+	)
+	// Advance ap to avoid clashes
+	vm.RunContext.Ap.Offset += 1
+
+	hintProcessor := CairoVmHintProcessor{}
+	hintData := any(HintData{
+		Ids:  idsManager,
+		Code: IS_ZERO_NONDET,
+	})
+
+	err := hintProcessor.ExecuteHint(vm, &hintData, nil, nil)
+	if err != nil {
+		t.Errorf("IS_ZERO_NONDET hint failed with error %s", err)
+	}
+	// Check memory[ap]
+	val, err := vm.Segments.Memory.GetFelt(vm.RunContext.Ap)
+	if err != nil || val != FeltOne() {
+		t.Error("Wrong/No value inserted into ap")
+	}
+}
+
+func TestIsZeroFalse(t *testing.T) {
+	vm := NewVirtualMachine()
+	vm.Segments.AddSegment()
+	idsManager := SetupIdsForTest(
+		map[string][]*MaybeRelocatable{
+			"x": {
+				NewMaybeRelocatableFelt(FeltOne()),
+			},
+		},
+		vm,
+	)
+	// Advance ap to avoid clashes
+	vm.RunContext.Ap.Offset += 1
+
+	hintProcessor := CairoVmHintProcessor{}
+	hintData := any(HintData{
+		Ids:  idsManager,
+		Code: IS_ZERO_NONDET,
+	})
+
+	err := hintProcessor.ExecuteHint(vm, &hintData, nil, nil)
+	if err != nil {
+		t.Errorf("IS_ZERO_NONDET hint failed with error %s", err)
+	}
+	// Check memory[ap]
+	val, err := vm.Segments.Memory.GetFelt(vm.RunContext.Ap)
+	if err != nil || val != FeltZero() {
+		t.Error("Wrong/No value inserted into ap")
+	}
+}