zig/lib/std/math/signbit.zig
mlugg 0fe3fd01dd
std: update std.builtin.Type fields to follow naming conventions
The compiler actually doesn't need any functional changes for this: Sema
does reification based on the tag indices of `std.builtin.Type` already!
So, no zig1.wasm update is necessary.

This change is necessary to disallow name clashes between fields and
decls on a type, which is a prerequisite of #9938.
2024-08-28 08:39:59 +01:00

24 lines
764 B
Zig

const std = @import("../std.zig");
const math = std.math;
const expect = std.testing.expect;
/// Returns whether x is negative or negative 0.
pub fn signbit(x: anytype) bool {
const T = @TypeOf(x);
const TBits = std.meta.Int(.unsigned, @typeInfo(T).float.bits);
return @as(TBits, @bitCast(x)) >> (@bitSizeOf(T) - 1) != 0;
}
test signbit {
inline for ([_]type{ f16, f32, f64, f80, f128 }) |T| {
try expect(!signbit(@as(T, 0.0)));
try expect(!signbit(@as(T, 1.0)));
try expect(signbit(@as(T, -2.0)));
try expect(signbit(@as(T, -0.0)));
try expect(!signbit(math.inf(T)));
try expect(signbit(-math.inf(T)));
try expect(!signbit(math.nan(T)));
try expect(signbit(-math.nan(T)));
}
}