zig/lib/std/math/isnormal.zig
Andrew Kelley ed36dbbd9c
mv std/ lib/
that's all this commit does. further commits will fix cli flags and
such.

see #2221
2019-09-25 23:35:41 -04:00

39 lines
1.1 KiB
Zig

const std = @import("../std.zig");
const math = std.math;
const expect = std.testing.expect;
const maxInt = std.math.maxInt;
// Returns whether x has a normalized representation (i.e. integer part of mantissa is 1).
pub fn isNormal(x: var) bool {
const T = @typeOf(x);
switch (T) {
f16 => {
const bits = @bitCast(u16, x);
return (bits + 1024) & 0x7FFF >= 2048;
},
f32 => {
const bits = @bitCast(u32, x);
return (bits + 0x00800000) & 0x7FFFFFFF >= 0x01000000;
},
f64 => {
const bits = @bitCast(u64, x);
return (bits + (1 << 52)) & (maxInt(u64) >> 1) >= (1 << 53);
},
else => {
@compileError("isNormal not implemented for " ++ @typeName(T));
},
}
}
test "math.isNormal" {
expect(!isNormal(math.nan(f16)));
expect(!isNormal(math.nan(f32)));
expect(!isNormal(math.nan(f64)));
expect(!isNormal(f16(0)));
expect(!isNormal(f32(0)));
expect(!isNormal(f64(0)));
expect(isNormal(f16(1.0)));
expect(isNormal(f32(1.0)));
expect(isNormal(f64(1.0)));
}