zig/std/math/isnan.zig

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const std = @import("../index.zig");
const math = std.math;
const assert = std.debug.assert;
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 & (@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 {
return isNan(x);
}
test "math.isNan" {
assert(isNan(math.nan(f16)));
assert(isNan(math.nan(f32)));
assert(isNan(math.nan(f64)));
assert(!isNan(f16(1.0)));
assert(!isNan(f32(1.0)));
assert(!isNan(f64(1.0)));
}