Zig 0.17.0-dev (Split by item)

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round

round.round

pub fn round(x_: f64) callconv(.c) f64

File

lib/compiler_rt/round.zig:68

Code

pub fn round(x_: f64) callconv(.c) f64 {
    const f64_toint = 1.0 / math.floatEps(f64);

    var x = x_;
    const u: u64 = @bitCast(x);
    const e = (u >> 52) & 0x7FF;
    var y: f64 = undefined;

    if (e >= 0x3FF + 52) {
        return x;
    }
    if (u >> 63 != 0) {
        x = -x;
    }
    if (e < 0x3ff - 1) {
        if (compiler_rt.want_float_exceptions) mem.doNotOptimizeAway(x + f64_toint);
        return 0 * @as(f64, @bitCast(u));
    }

    y = x + f64_toint - f64_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 >> 63 != 0) {
        return -y;
    } else {
        return y;
    }
}