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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);
return switch (T) {
f16 => signbit16(x),
f32 => signbit32(x),
f64 => signbit64(x),
f128 => signbit128(x),
else => @compileError("signbit not implemented for " ++ @typeName(T)),
};
}
fn signbit16(x: f16) bool {
const bits = @bitCast(u16, x);
return bits >> 15 != 0;
}
fn signbit32(x: f32) bool {
const bits = @bitCast(u32, x);
return bits >> 31 != 0;
}
fn signbit64(x: f64) bool {
const bits = @bitCast(u64, x);
return bits >> 63 != 0;
}
fn signbit128(x: f128) bool {
const bits = @bitCast(u128, x);
return bits >> 127 != 0;
}
test "math.signbit" {
try expect(signbit(@as(f16, 4.0)) == signbit16(4.0));
try expect(signbit(@as(f32, 4.0)) == signbit32(4.0));
try expect(signbit(@as(f64, 4.0)) == signbit64(4.0));
try expect(signbit(@as(f128, 4.0)) == signbit128(4.0));
}
test "math.signbit16" {
try expect(!signbit16(4.0));
try expect(signbit16(-3.0));
}
test "math.signbit32" {
try expect(!signbit32(4.0));
try expect(signbit32(-3.0));
}
test "math.signbit64" {
try expect(!signbit64(4.0));
try expect(signbit64(-3.0));
}
test "math.signbit128" {
try expect(!signbit128(4.0));
try expect(signbit128(-3.0));
}
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