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//===========================================================================

//

//      s_sin.c

//

//      Part of the standard mathematical function library

//

//===========================================================================

//####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

// This file is part of eCos, the Embedded Configurable Operating System.

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.

//

// eCos is free software; you can redistribute it and/or modify it under

// the terms of the GNU General Public License as published by the Free

// Software Foundation; either version 2 or (at your option) any later version.

//

// eCos is distributed in the hope that it will be useful, but WITHOUT ANY

// WARRANTY; without even the implied warranty of MERCHANTABILITY or

// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

// for more details.

//

// You should have received a copy of the GNU General Public License along

// with eCos; if not, write to the Free Software Foundation, Inc.,

// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

//

// As a special exception, if other files instantiate templates or use macros

// or inline functions from this file, or you compile this file and link it

// with other works to produce a work based on this file, this file does not

// by itself cause the resulting work to be covered by the GNU General Public

// License. However the source code for this file must still be made available

// in accordance with section (3) of the GNU General Public License.

//

// This exception does not invalidate any other reasons why a work based on

// this file might be covered by the GNU General Public License.

//

// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.

// at http://sources.redhat.com/ecos/ecos-license/

// -------------------------------------------

//####ECOSGPLCOPYRIGHTEND####

//===========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):   jlarmour

// Contributors:  jlarmour

// Date:        1998-02-13

// Purpose:     

// Description: 

// Usage:       

//

//####DESCRIPTIONEND####

//

//===========================================================================

// CONFIGURATION

#include <pkgconf/libm.h>   // Configuration header

// Include the Math library?

#ifdef CYGPKG_LIBM     

// Derived from code with the following copyright

/* @(#)s_sin.c 1.3 95/01/18 */

/*

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

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

 *

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

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

 * software is freely granted, provided that this notice

 * is preserved.

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

 */

/* sin(x)

 * Return sine function of x.

 *

 * kernel function:

 *      __kernel_sin            ... sine function on [-pi/4,pi/4]

 *      __kernel_cos            ... cose function on [-pi/4,pi/4]

 *      __ieee754_rem_pio2      ... argument reduction routine

 *

 * Method.

 *      Let S,C and T denote the sin, cos and tan respectively on

 *      [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2

 *      in [-pi/4 , +pi/4], and let n = k mod 4.

 *      We have

 *

 *          n        sin(x)      cos(x)        tan(x)

 *     ----------------------------------------------------------

 *          0          S           C             T

 *          1          C          -S            -1/T

 *          2         -S          -C             T

 *          3         -C           S            -1/T

 *     ----------------------------------------------------------

 *

 * Special cases:

 *      Let trig be any of sin, cos, or tan.

 *      trig(+-INF)  is NaN, with signals;

 *      trig(NaN)    is that NaN;

 *

 * Accuracy:

 *      TRIG(x) returns trig(x) nearly rounded

 */

#include "mathincl/fdlibm.h"

        double sin(double x)

{

        double y[2],z=0.0;

        int n, ix;

    /* High word of x. */

        ix = CYG_LIBM_HI(x);

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

        ix &= 0x7fffffff;

        if(ix <= 0x3fe921fb) return __kernel_sin(x,z,0);

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

        else if (ix>=0x7ff00000) return x-x;

    /* argument reduction needed */

        else {

            n = __ieee754_rem_pio2(x,y);

            switch(n&3) {

                case 0: return  __kernel_sin(y[0],y[1],1);

                case 1: return  __kernel_cos(y[0],y[1]);

                case 2: return -__kernel_sin(y[0],y[1],1);

                default:

                        return -__kernel_cos(y[0],y[1]);

            }

        }

}

#endif // ifdef CYGPKG_LIBM     

// EOF s_sin.c