zig/std/math/copysign.zig
Andrew Kelley c9fc8bd802 workaround for llvm bug
See #393 for details
2017-06-19 14:36:33 -04:00

51 lines
1.3 KiB
Zig

const math = @import("index.zig");
const assert = @import("../debug.zig").assert;
// TODO issue #393
pub const copysign = copysign_workaround;
pub fn copysign_workaround(comptime T: type, x: T, y: T) -> T {
switch (T) {
f32 => @inlineCall(copysign32, x, y),
f64 => @inlineCall(copysign64, x, y),
else => @compileError("copysign not implemented for " ++ @typeName(T)),
}
}
fn copysign32(x: f32, y: f32) -> f32 {
const ux = @bitCast(u32, x);
const uy = @bitCast(u32, y);
const h1 = ux & (@maxValue(u32) / 2);
const h2 = uy & (u32(1) << 31);
@bitCast(f32, h1 | h2)
}
fn copysign64(x: f64, y: f64) -> f64 {
const ux = @bitCast(u64, x);
const uy = @bitCast(u64, y);
const h1 = ux & (@maxValue(u64) / 2);
const h2 = uy & (u64(1) << 63);
@bitCast(f64, h1 | h2)
}
test "math.copysign" {
assert(copysign(f32, 1.0, 1.0) == copysign32(1.0, 1.0));
assert(copysign(f64, 1.0, 1.0) == copysign64(1.0, 1.0));
}
test "math.copysign32" {
assert(copysign32(5.0, 1.0) == 5.0);
assert(copysign32(5.0, -1.0) == -5.0);
assert(copysign32(-5.0, -1.0) == -5.0);
assert(copysign32(-5.0, 1.0) == 5.0);
}
test "math.copysign64" {
assert(copysign64(5.0, 1.0) == 5.0);
assert(copysign64(5.0, -1.0) == -5.0);
assert(copysign64(-5.0, -1.0) == -5.0);
assert(copysign64(-5.0, 1.0) == 5.0);
}