/* origin: FreeBSD /usr/src/lib/msun/src/s_sinf.c */

/*

 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.

 * Optimized by Bruce D. Evans.

 */

/*

 * ====================================================

 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.

 *

 * Developed at SunPro, a Sun Microsystems, Inc. business.

 * Permission to use, copy, modify, and distribute this

 * software is freely granted, provided that this notice

 * is preserved.

 * ====================================================

 */

use super::{k_cosf, k_sinf, rem_pio2f};

/* Small multiples of pi/2 rounded to double precision. */

const PI_2: f64 = 0.5 * 3.1415926535897931160E+00;

const S1PIO2: f64 = 1.0 * PI_2; /* 0x3FF921FB, 0x54442D18 */

const S2PIO2: f64 = 2.0 * PI_2; /* 0x400921FB, 0x54442D18 */

const S3PIO2: f64 = 3.0 * PI_2; /* 0x4012D97C, 0x7F3321D2 */

const S4PIO2: f64 = 4.0 * PI_2; /* 0x401921FB, 0x54442D18 */

/// Both the sine and cosine of `x` (f32).

///

/// `x` is specified in radians and the return value is (sin(x), cos(x)).

#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]

pub fn sincosf(x: f32) -> (f32, f32) {

    let s: f32;

    let c: f32;

    let mut ix: u32;

    let sign: bool;

    ix = x.to_bits();

    sign = (ix >> 31) != 0;

    ix &= 0x7fffffff;

    /* |x| ~<= pi/4 */

    if ix <= 0x3f490fda {

        /* |x| < 2**-12 */

        if ix < 0x39800000 {

            /* raise inexact if x!=0 and underflow if subnormal */

            let x1p120 = f32::from_bits(0x7b800000); // 0x1p120 == 2^120

            if ix < 0x00100000 {

                force_eval!(x / x1p120);

            } else {

                force_eval!(x + x1p120);

            }

            return (x, 1.0);

        }

        return (k_sinf(x as f64), k_cosf(x as f64));

    }

    /* |x| ~<= 5*pi/4 */

    if ix <= 0x407b53d1 {

        if ix <= 0x4016cbe3 {

            /* |x| ~<= 3pi/4 */

            if sign {

                s = -k_cosf(x as f64 + S1PIO2);

                c = k_sinf(x as f64 + S1PIO2);

            } else {

                s = k_cosf(S1PIO2 - x as f64);

                c = k_sinf(S1PIO2 - x as f64);

            }

        }

        /* -sin(x+c) is not correct if x+c could be 0: -0 vs +0 */

        else {

            if sign {

                s = -k_sinf(x as f64 + S2PIO2);

                c = -k_cosf(x as f64 + S2PIO2);

            } else {

                s = -k_sinf(x as f64 - S2PIO2);

                c = -k_cosf(x as f64 - S2PIO2);

            }

        }

        return (s, c);

    }

    /* |x| ~<= 9*pi/4 */

    if ix <= 0x40e231d5 {

        if ix <= 0x40afeddf {

            /* |x| ~<= 7*pi/4 */

            if sign {

                s = k_cosf(x as f64 + S3PIO2);

                c = -k_sinf(x as f64 + S3PIO2);

            } else {

                s = -k_cosf(x as f64 - S3PIO2);

                c = k_sinf(x as f64 - S3PIO2);

            }

        } else {

            if sign {

                s = k_sinf(x as f64 + S4PIO2);

                c = k_cosf(x as f64 + S4PIO2);

            } else {

                s = k_sinf(x as f64 - S4PIO2);

                c = k_cosf(x as f64 - S4PIO2);

            }

        }

        return (s, c);

    }

    /* sin(Inf or NaN) is NaN */

    if ix >= 0x7f800000 {

        let rv = x - x;

        return (rv, rv);

    }

    /* general argument reduction needed */

    let (n, y) = rem_pio2f(x);

    s = k_sinf(y);

    c = k_cosf(y);

    match n & 3 {

        0 => (s, c),

        1 => (c, -s),

        2 => (-s, -c),

        3 => (-c, s),

        #[cfg(debug_assertions)]

        _ => unreachable!(),

        #[cfg(not(debug_assertions))]

        _ => (0.0, 1.0),

    }

}

// PowerPC tests are failing on LLVM 13: https://github.com/rust-lang/rust/issues/88520

#[cfg(not(target_arch = "powerpc64"))]

#[cfg(test)]

mod tests {

    use super::sincosf;

    #[test]

    fn rotational_symmetry() {

        use core::f32::consts::PI;

        const N: usize = 24;

        for n in 0..N {

            let theta = 2. * PI * (n as f32) / (N as f32);

            let (s, c) = sincosf(theta);

            let (s_plus, c_plus) = sincosf(theta + 2. * PI);

            let (s_minus, c_minus) = sincosf(theta - 2. * PI);

            const TOLERANCE: f32 = 1e-6;

            assert!(

                (s - s_plus).abs() < TOLERANCE,

                "|{} - {}| = {} >= {}",

                s,

                s_plus,

                (s - s_plus).abs(),

                TOLERANCE

            );

            assert!(

                (s - s_minus).abs() < TOLERANCE,

                "|{} - {}| = {} >= {}",

                s,

                s_minus,

                (s - s_minus).abs(),

                TOLERANCE

            );

            assert!(

                (c - c_plus).abs() < TOLERANCE,

                "|{} - {}| = {} >= {}",

                c,

                c_plus,

                (c - c_plus).abs(),

                TOLERANCE

            );

            assert!(

                (c - c_minus).abs() < TOLERANCE,

                "|{} - {}| = {} >= {}",

                c,

                c_minus,

                (c - c_minus).abs(),

                TOLERANCE

            );

        }

    }

}