//===========================================================================
//
//      ef_fmod.c
//
//      Part of the standard mathematical function library
//
//===========================================================================
// ####ECOSGPLCOPYRIGHTBEGIN####
// -------------------------------------------
// This file is part of eCos, the Embedded Configurable Operating System.
// Copyright (C) 2012 Free Software Foundation, 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.,
// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 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 v2.
//
// This exception does not invalidate any other reasons why a work based
// on this file might be covered by the GNU General Public License.
// -------------------------------------------
// ####ECOSGPLCOPYRIGHTEND####
//===========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):
// Contributors: visar, ilijak
// Date:        2012-03-08
// 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


/* ef_fmod.c -- float version of e_fmod.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 */

/*
 * ====================================================
 * 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.
 * ====================================================
 */

/*
 * __ieee754_fmodf(x,y)
 * Return x mod y in exact arithmetic
 * Method: shift and subtract
 */


#include "mathincl/fdlibm.h"

#ifdef __STDC__
static const float one = 1.0, Zero[] = {0.0, -0.0,};
#else
static float one = 1.0, Zero[] = {0.0, -0.0,};
#endif

#ifdef __STDC__
	float __ieee754_fmodf(float x, float y)
#else
	float __ieee754_fmodf(x,y)
	float x,y ;
#endif
{
	__int32_t n,hx,hy,hz,ix,iy,sx,i;

	hx = CYG_LIBM_WORD(x);
	hy = CYG_LIBM_WORD(y);
	sx = hx&0x80000000;		/* sign of x */
	hx ^=sx;		/* |x| */
	hy &= 0x7fffffff;	/* |y| */

    /* purge off exception values */
	if(FLT_UWORD_IS_ZERO(hy)||
	   !FLT_UWORD_IS_FINITE(hx)||
	   FLT_UWORD_IS_NAN(hy))
	    return (x*y)/(x*y);
	if(hx<hy) return x;			/* |x|<|y| return x */
	if(hx==hy)
	    return Zero[(__uint32_t)sx>>31];	/* |x|=|y| return x*0*/

    /* Note: y cannot be zero if we reach here. */

    /* determine ix = ilogb(x) */
	if(FLT_UWORD_IS_SUBNORMAL(hx)) {	/* subnormal x */
	    for (ix = -126,i=(hx<<8); i>0; i<<=1) ix -=1;
	} else ix = (hx>>23)-127;

    /* determine iy = ilogb(y) */
	if(FLT_UWORD_IS_SUBNORMAL(hy)) {	/* subnormal y */
	    for (iy = -126,i=(hy<<8); i>=0; i<<=1) iy -=1;
	} else iy = (hy>>23)-127;

    /* set up {hx,lx}, {hy,ly} and align y to x */
	if(ix >= -126)
	    hx = 0x00800000|(0x007fffff&hx);
	else {		/* subnormal x, shift x to normal */
	    n = -126-ix;
	    hx = hx<<n;
	}
	if(iy >= -126)
	    hy = 0x00800000|(0x007fffff&hy);
	else {		/* subnormal y, shift y to normal */
	    n = -126-iy;
	    hy = hy<<n;
	}

    /* fix point fmod */
	n = ix - iy;
	while(n--) {
	    hz=hx-hy;
	    if(hz<0){hx = hx+hx;}
	    else {
		if(hz==0)		/* return sign(x)*0 */
		    return Zero[(__uint32_t)sx>>31];
		hx = hz+hz;
	    }
	}
	hz=hx-hy;
	if(hz>=0) {hx=hz;}

    /* convert back to floating value and restore the sign */
	if(hx==0)			/* return sign(x)*0 */
	    return Zero[(__uint32_t)sx>>31];
	while(hx<0x00800000) {		/* normalize x */
	    hx = hx+hx;
	    iy -= 1;
	}
	if(iy>= -126) {		/* normalize output */
	    hx = ((hx-0x00800000)|((iy+127)<<23));
	    SET_FLOAT_WORD(x,hx|sx);
	} else {		/* subnormal output */
	    /* If denormals are not supported, this code will generate a
	       zero representation.  */
	    n = -126 - iy;
	    hx >>= n;
	    SET_FLOAT_WORD(x,hx|sx);
	    x *= one;		/* create necessary signal */
	}
	return x;		/* exact output */
}

#endif // ifdef CYGPKG_LIBM

// EOF ef_fmod.c
