Zig 0.17.0-dev (Split by item)

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tanf

tan.tanf
pub fn tanf(x: f32) callconv(.c) f32

File

lib/compiler_rt/tan.zig:43

Code

pub fn tanf(x: f32) callconv(.c) f32 {
    // Small multiples of pi/2 rounded to double precision.
    const t1pio2: f64 = 1.0 * math.pi / 2.0; // 0x3FF921FB, 0x54442D18
    const t2pio2: f64 = 2.0 * math.pi / 2.0; // 0x400921FB, 0x54442D18
    const t3pio2: f64 = 3.0 * math.pi / 2.0; // 0x4012D97C, 0x7F3321D2
    const t4pio2: f64 = 4.0 * math.pi / 2.0; // 0x401921FB, 0x54442D18

    var ix: u32 = @bitCast(x);
    const sign = ix >> 31 != 0;
    ix &= 0x7fffffff;

    if (ix <= 0x3f490fda) { // |x| ~<= pi/4
        if (ix < 0x39800000) { // |x| < 2**-12
            // raise inexact if x!=0 and underflow if subnormal
            if (compiler_rt.want_float_exceptions) {
                if (ix < 0x00800000) {
                    mem.doNotOptimizeAway(x / 0x1p120);
                } else {
                    mem.doNotOptimizeAway(x + 0x1p120);
                }
            }
            return x;
        }
        return kernel.tandf(x, false);
    }
    if (ix <= 0x407b53d1) { // |x| ~<= 5*pi/4
        if (ix <= 0x4016cbe3) { // |x| ~<= 3pi/4
            return kernel.tandf((if (sign) x + t1pio2 else x - t1pio2), true);
        } else {
            return kernel.tandf((if (sign) x + t2pio2 else x - t2pio2), false);
        }
    }
    if (ix <= 0x40e231d5) { // |x| ~<= 9*pi/4
        if (ix <= 0x40afeddf) { // |x| ~<= 7*pi/4
            return kernel.tandf((if (sign) x + t3pio2 else x - t3pio2), true);
        } else {
            return kernel.tandf((if (sign) x + t4pio2 else x - t4pio2), false);
        }
    }

    // tan(Inf or NaN) is NaN
    if (ix >= 0x7f800000) {
        return x - x;
    }

    var y: f64 = undefined;
    const n = rem_pio2f(x, &y);
    return kernel.tandf(y, n & 1 != 0);
}