zig/std/math/isnan.zig
Andrew Kelley c2db077574
std.debug.assert: remove special case for test builds
Previously, std.debug.assert would `@panic` in test builds,
if the assertion failed. Now, it's always `unreachable`.

This makes release mode test builds more accurately test
the actual code that will be run.

However this requires tests to call `std.testing.expect`
rather than `std.debug.assert` to make sure output is correct.

Here is the explanation of when to use either one, copied from
the assert doc comments:

Inside a test block, it is best to use the `std.testing` module
rather than assert, because assert may not detect a test failure
in ReleaseFast and ReleaseSafe mode. Outside of a test block, assert
is the correct function to use.

closes #1304
2019-02-08 18:23:38 -05:00

41 lines
1.1 KiB
Zig

const std = @import("../index.zig");
const math = std.math;
const expect = std.testing.expect;
const maxInt = std.math.maxInt;
pub fn isNan(x: var) bool {
const T = @typeOf(x);
switch (T) {
f16 => {
const bits = @bitCast(u16, x);
return (bits & 0x7fff) > 0x7c00;
},
f32 => {
const bits = @bitCast(u32, x);
return bits & 0x7FFFFFFF > 0x7F800000;
},
f64 => {
const bits = @bitCast(u64, x);
return (bits & (maxInt(u64) >> 1)) > (u64(0x7FF) << 52);
},
else => {
@compileError("isNan not implemented for " ++ @typeName(T));
},
}
}
/// Note: A signalling nan is identical to a standard nan right now but may have a different bit
/// representation in the future when required.
pub fn isSignalNan(x: var) bool {
return isNan(x);
}
test "math.isNan" {
expect(isNan(math.nan(f16)));
expect(isNan(math.nan(f32)));
expect(isNan(math.nan(f64)));
expect(!isNan(f16(1.0)));
expect(!isNan(f32(1.0)));
expect(!isNan(f64(1.0)));
}