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c: Implement fmax and fmaxf

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LemonBoy 2021-04-20 15:44:21 +02:00
parent fcfe25710b
commit a4e2539b09
1 changed files with 29 additions and 0 deletions
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29
lib/std/special/c.zig
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@ -909,6 +909,35 @@ test "fmin, fminf" {
}
}
fn generic_fmax(comptime T: type, x: T, y: T) T {
if (isNan(x))
return y;
if (isNan(y))
return x;
return if (x < y) y else x;
}
export fn fmaxf(x: f32, y: f32) callconv(.C) f32 {
return generic_fmax(f32, x, y);
}
export fn fmax(x: f64, y: f64) callconv(.C) f64 {
return generic_fmax(f64, x, y);
}
test "fmax, fmaxf" {
inline for ([_]type{ f32, f64 }) |T| {
const nan_val = math.nan(T);
std.testing.expect(isNan(generic_fmax(T, nan_val, nan_val)));
std.testing.expectEqual(@as(T, 1.0), generic_fmax(T, nan_val, 1.0));
std.testing.expectEqual(@as(T, 1.0), generic_fmax(T, 1.0, nan_val));
std.testing.expectEqual(@as(T, 10.0), generic_fmax(T, 1.0, 10.0));
std.testing.expectEqual(@as(T, 1.0), generic_fmax(T, 1.0, -1.0));
}
}
// NOTE: The original code is full of implicit signed -> unsigned assumptions and u32 wraparound
// behaviour. Most intermediate i32 values are changed to u32 where appropriate but there are
// potentially some edge cases remaining that are not handled in the same way.