Zig 0.17.0-dev (Split by item)

This is an example of documentation generated by ZigDoc, an alternative to Zig's built-in Auto Doc feature. See also examples in other modes/formats. The project being documented here (as the example) is the Zig library itself.

roundq

round.roundq
pub fn roundq(x_: f128) callconv(.c) f128

File

lib/compiler_rt/round.zig:108

Code

pub fn roundq(x_: f128) callconv(.c) f128 {
    const f128_toint = 1.0 / math.floatEps(f128);

    var x = x_;
    const u: u128 = @bitCast(x);
    const e = (u >> 112) & 0x7FFF;
    var y: f128 = undefined;

    if (e >= 0x3FFF + 112) {
        return x;
    }
    if (u >> 127 != 0) {
        x = -x;
    }
    if (e < 0x3FFF - 1) {
        if (compiler_rt.want_float_exceptions) mem.doNotOptimizeAway(x + f128_toint);
        return 0 * @as(f128, @bitCast(u));
    }

    y = x + f128_toint - f128_toint - x;
    if (y > 0.5) {
        y = y + x - 1;
    } else if (y <= -0.5) {
        y = y + x + 1;
    } else {
        y = y + x;
    }

    if (u >> 127 != 0) {
        return -y;
    } else {
        return y;
    }
}