26 lines
850 B
Zig
26 lines
850 B
Zig
const compiler_rt = @import("../compiler_rt.zig");
|
|
const symbol = compiler_rt.symbol;
|
|
const testing = @import("std").testing;
|
|
|
|
comptime {
|
|
symbol(&__subvsi3, "__subvsi3");
|
|
}
|
|
|
|
pub fn __subvsi3(a: i32, b: i32) callconv(.c) i32 {
|
|
const sum = a -% b;
|
|
// Overflow occurred iff the operands have opposite signs, and the sign of the
|
|
// sum is the opposite of the lhs sign.
|
|
if (((a ^ b) & (sum ^ a)) < 0) @panic("compiler-rt: integer overflow");
|
|
return sum;
|
|
}
|
|
|
|
test "subvsi3" {
|
|
// min i32 = -2147483648
|
|
// max i32 = 2147483647
|
|
// TODO write panic handler for testing panics
|
|
// try test__subvsi3(-2147483648, -1, -1); // panic
|
|
// try test__subvsi3(2147483647, 1, 1); // panic
|
|
try testing.expectEqual(-2147483648, __subvsi3(-2147483647, 1));
|
|
try testing.expectEqual(2147483647, __subvsi3(2147483646, -1));
|
|
}
|