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// RUN: %dafny /compile:0 "%s" > "%t"
// RUN: %diff "%s.expect" "%t"
// Spec# and Boogie and Chalice: The program will be
// the same, except that these languages do not check
// for any kind of termination. Also, in Spec#, there
// is an issue of potential overflows.
// Benchmark1
method Add(x: int, y: int) returns (r: int)
ensures r == x+y;
{
r := x;
if (y < 0) {
var n := y;
while (n != 0)
invariant r == x+y-n && 0 <= -n;
{
r := r - 1;
n := n + 1;
}
} else {
var n := y;
while (n != 0)
invariant r == x+y-n && 0 <= n;
{
r := r + 1;
n := n - 1;
}
}
}
method Mul(x: int, y: int) returns (r: int)
ensures r == x*y;
decreases x < 0, x;
{
if (x == 0) {
r := 0;
} else if (x < 0) {
r := Mul(-x, y);
r := -r;
} else {
r := Mul(x-1, y);
r := Add(r, y);
}
}
// ---------------------------
method Main() {
TestAdd(3, 180);
TestAdd(3, -180);
TestAdd(0, 1);
TestMul(3, 180);
TestMul(3, -180);
TestMul(180, 3);
TestMul(-180, 3);
TestMul(0, 1);
TestMul(1, 0);
}
method TestAdd(x: int, y: int) {
print x, " + ", y, " = ";
var z := Add(x, y);
print z, "\n";
}
method TestMul(x: int, y: int) {
print x, " * ", y, " = ";
var z := Mul(x, y);
print z, "\n";
}
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