/*
 * $Id: math_kernel_scalbn.c,v 1.3 2005-02-25 10:14:21 obarthel Exp $
 *
 * :ts=4
 *
 * Portable ISO 'C' (1994) runtime library for the Amiga computer
 * Copyright (c) 2002-2005 by Olaf Barthel <olsen@sourcery.han.de>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Neither the name of Olaf Barthel nor the names of contributors
 *     may be used to endorse or promote products derived from this
 *     software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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.
 *
 *
 * PowerPC math library based in part on work by Sun Microsystems
 * 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.
 */

#ifndef _MATH_HEADERS_H
#include "math_headers.h"
#endif /* _MATH_HEADERS_H */

/****************************************************************************/

#if defined(FLOATING_POINT_SUPPORT) && defined(PPC_FLOATING_POINT_SUPPORT)

/****************************************************************************/

INLINE STATIC double copysign(double x, double y)
{
	unsigned int hx,hy;

	GET_HIGH_WORD(hx,x);
	GET_HIGH_WORD(hy,y);
	SET_HIGH_WORD(x,(hx&0x7fffffff)|(hy&0x80000000));

	return x;
}

static const double
huge	= 1.0e+300,
tiny	= 1.0e-300,
two54   = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
twom54  = 5.55111512312578270212e-17; /* 0x3C900000, 0x00000000 */

double __scalbn (double x, int n)
{
	int  k,hx,lx;
	EXTRACT_WORDS(hx,lx,x);
	k = (hx&0x7ff00000)>>20;		/* extract exponent */
	if (k==0) {				/* 0 or subnormal x */
		if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
	    x *= two54; 
	    GET_HIGH_WORD(hx,x);
	    k = ((hx&0x7ff00000)>>20) - 54; 
		if (n< -50000) return tiny*x; 	/*underflow*/
	}
	if (k==0x7ff) return x+x;		/* NaN or Inf */
	k = k+n; 
	if (k >  0x7fe) return huge*copysign(huge,x); /* overflow  */
	if (k > 0) 				/* normal result */
	{SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20)); return x;}
	if (k <= -54) {
		if (n > 50000) 	/* in case integer overflow in n+k */
		return huge*copysign(huge,x);	/*overflow*/
	    else return tiny*copysign(tiny,x); 	/*underflow*/
	}
	k += 54;				/* subnormal result */
	SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20));
	return x*twom54;
}

/****************************************************************************/

#endif /* FLOATING_POINT_SUPPORT && PPC_FLOATING_POINT_SUPPORT */
