zig/std/math/isnan.zig
Marc Tiehuis 5bbec42a4e Add math special case tests and general fixes
- Should cover special case inputs for most functions
 - Fixed a number of runtime panicking behaviour reliant on shift
   overflow/division by zero etc.
2017-06-20 23:10:22 +12:00

33 lines
858 B
Zig

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