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// Ported from musl, which is licensed under the MIT license:
// https://git.musl-libc.org/cgit/musl/tree/COPYRIGHT
//
// https://git.musl-libc.org/cgit/musl/tree/src/math/copysignf.c
// https://git.musl-libc.org/cgit/musl/tree/src/math/copysign.c
const std = @import("../std.zig");
const math = std.math;
const expect = std.testing.expect;
const maxInt = std.math.maxInt;
/// Returns a value with the magnitude of x and the sign of y.
pub fn copysign(comptime T: type, x: T, y: T) T {
return switch (T) {
f16 => copysign16(x, y),
f32 => copysign32(x, y),
f64 => copysign64(x, y),
else => @compileError("copysign not implemented for " ++ @typeName(T)),
};
}
fn copysign16(x: f16, y: f16) f16 {
const ux = @bitCast(u16, x);
const uy = @bitCast(u16, y);
const h1 = ux & (maxInt(u16) / 2);
const h2 = uy & (u16(1) << 15);
return @bitCast(f16, h1 | h2);
}
fn copysign32(x: f32, y: f32) f32 {
const ux = @bitCast(u32, x);
const uy = @bitCast(u32, y);
const h1 = ux & (maxInt(u32) / 2);
const h2 = uy & (u32(1) << 31);
return @bitCast(f32, h1 | h2);
}
fn copysign64(x: f64, y: f64) f64 {
const ux = @bitCast(u64, x);
const uy = @bitCast(u64, y);
const h1 = ux & (maxInt(u64) / 2);
const h2 = uy & (u64(1) << 63);
return @bitCast(f64, h1 | h2);
}
test "math.copysign" {
expect(copysign(f16, 1.0, 1.0) == copysign16(1.0, 1.0));
expect(copysign(f32, 1.0, 1.0) == copysign32(1.0, 1.0));
expect(copysign(f64, 1.0, 1.0) == copysign64(1.0, 1.0));
}
test "math.copysign16" {
expect(copysign16(5.0, 1.0) == 5.0);
expect(copysign16(5.0, -1.0) == -5.0);
expect(copysign16(-5.0, -1.0) == -5.0);
expect(copysign16(-5.0, 1.0) == 5.0);
}
test "math.copysign32" {
expect(copysign32(5.0, 1.0) == 5.0);
expect(copysign32(5.0, -1.0) == -5.0);
expect(copysign32(-5.0, -1.0) == -5.0);
expect(copysign32(-5.0, 1.0) == 5.0);
}
test "math.copysign64" {
expect(copysign64(5.0, 1.0) == 5.0);
expect(copysign64(5.0, -1.0) == -5.0);
expect(copysign64(-5.0, -1.0) == -5.0);
expect(copysign64(-5.0, 1.0) == 5.0);
}
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