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const std = @import("../index.zig");
const math = std.math;
const assert = std.debug.assert;
pub fn copysign(comptime T: type, x: T, y: T) -> T {
return switch (T) {
f32 => copysign32(x, y),
f64 => 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);
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 & (@maxValue(u64) / 2);
const h2 = uy & (u64(1) << 63);
return @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);
}
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