zig/std/math/isfinite.zig
2018-10-26 15:01:51 -04:00

41 lines
1.1 KiB
Zig

const std = @import("../index.zig");
const math = std.math;
const assert = std.debug.assert;
const maxInt = std.math.maxInt;
pub fn isFinite(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) < (0x7FF << 52);
},
else => {
@compileError("isFinite not implemented for " ++ @typeName(T));
},
}
}
test "math.isFinite" {
assert(isFinite(f16(0.0)));
assert(isFinite(f16(-0.0)));
assert(isFinite(f32(0.0)));
assert(isFinite(f32(-0.0)));
assert(isFinite(f64(0.0)));
assert(isFinite(f64(-0.0)));
assert(!isFinite(math.inf(f16)));
assert(!isFinite(-math.inf(f16)));
assert(!isFinite(math.inf(f32)));
assert(!isFinite(-math.inf(f32)));
assert(!isFinite(math.inf(f64)));
assert(!isFinite(-math.inf(f64)));
}