/*-
 * Copyright (c) 2017, 2023 Steven G. Kargl
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * See ../src/s_sinpi.c for implementation details.
 */

#ifdef __i386__
#include <ieeefp.h>
#endif
#include <stdint.h>

#include "fpmath.h"
#include "math.h"
#include "math_private.h"

static const union IEEEl2bits
pi_hi_u = LD80C(0xc90fdaa200000000,   1, 3.14159265346825122833e+00L),
pi_lo_u = LD80C(0x85a308d313198a2e, -33, 1.21542010130123852029e-10L);
#define pi_hi   (pi_hi_u.e)
#define pi_lo   (pi_lo_u.e)

#include "k_cospil.h"
#include "k_sinpil.h"

volatile static const double vzero = 0;

long double
sinpil(long double x)
{
        long double ax, hi, lo, s;
        uint64_t lx, m;
        uint32_t j0;
        uint16_t hx, ix;

        EXTRACT_LDBL80_WORDS(hx, lx, x);
        ix = hx & 0x7fff;
        INSERT_LDBL80_WORDS(ax, ix, lx);

        ENTERI();

        if (ix < 0x3fff) {                      /* |x| < 1 */
                if (ix < 0x3ffd) {              /* |x| < 0.25 */
                        if (ix < 0x3fdd) {      /* |x| < 0x1p-34 */
                                if (x == 0)
                                        RETURNI(x);
                                INSERT_LDBL80_WORDS(hi, hx,
                                    lx & 0xffffffff00000000ull);
                                hi *= 0x1p63L;
                                lo = x * 0x1p63L - hi;
                                s = (pi_lo + pi_hi) * lo + pi_lo * hi +
                                    pi_hi * hi;
                                RETURNI(s * 0x1p-63L);
                        }
                        s = __kernel_sinpil(ax);
                        RETURNI((hx & 0x8000) ? -s : s);
                }

                if (ix < 0x3ffe)                        /* |x| < 0.5 */
                        s = __kernel_cospil(0.5 - ax);
                else if (lx < 0xc000000000000000ull)    /* |x| < 0.75 */
                        s = __kernel_cospil(ax - 0.5);
                else
                        s = __kernel_sinpil(1 - ax);
                RETURNI((hx & 0x8000) ? -s : s);
        }

        if (ix < 0x403e) {                      /* 1 <= |x| < 0x1p63 */
                FFLOORL80(x, j0, ix, lx);       /* Integer part of ax. */
                ax -= x;
                EXTRACT_LDBL80_WORDS(ix, lx, ax);

                if (ix == 0) {
                        s = 0;
                } else {
                        if (ix < 0x3ffe) {              /* |x| < 0.5 */
                                if (ix < 0x3ffd)        /* |x| < 0.25 */
                                        s = __kernel_sinpil(ax);
                                else 
                                        s = __kernel_cospil(0.5 - ax);
                        } else {
                                                        /* |x| < 0.75 */
                                if (lx < 0xc000000000000000ull)
                                        s = __kernel_cospil(ax - 0.5);
                                else
                                        s = __kernel_sinpil(1 - ax);
                        }

                        if (j0 > 40)
                                x -= 0x1p40;
                        if (j0 > 30)
                                x -= 0x1p30;
                        j0 = (uint32_t)x;
                        if (j0 & 1) s = -s;
                }
                RETURNI((hx & 0x8000) ? -s : s);
        }

        /* x = +-inf or nan. */
        if (ix >= 0x7fff)
                RETURNI(vzero / vzero);

        /*
         * |x| >= 0x1p63 is always an integer, so return +-0.
         */
        RETURNI(copysignl(0, x));
}