    // 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/__expo2f.c

    // https://git.musl-libc.org/cgit/musl/tree/src/math/__expo2.c

    const math = @import("../math.zig");

    /// Returns exp(x) / 2 for x >= log(maxFloat(T)).
    pub fn expo2(x: anytype) @TypeOf(x) {
        const T = @TypeOf(x);
        return switch (T) {
            f32 => expo2f(x),
            f64 => expo2d(x),
            else => @compileError("expo2 not implemented for " ++ @typeName(T)),
        };
    }

    fn expo2f(x: f32) f32 {
        const k: u32 = 235;
        const kln2 = 0x1.45C778p+7;

        const u = (0x7F + k / 2) << 23;
        const scale = @as(f32, @bitCast(u));
        return @exp(x - kln2) * scale * scale;
    }

    fn expo2d(x: f64) f64 {
        const k: u32 = 2043;
        const kln2 = 0x1.62066151ADD8BP+10;

        const u = (0x3FF + k / 2) << 20;
        const scale = @as(f64, @bitCast(@as(u64, u) << 32));
        return @exp(x - kln2) * scale * scale;
    }