[picodrive.git] / platform / gp2x / code940 / uClibc / s_scalbn.c

/* @(#)s_scalbn.c 5.1 93/09/24 */
/*
 * ====================================================
 * 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.
 * ====================================================
 */

#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$NetBSD: s_scalbn.c,v 1.8 1995/05/10 20:48:08 jtc Exp $";
#endif

/*
 * scalbn (double x, int n)
 * scalbn(x,n) returns x* 2**n  computed by  exponent
 * manipulation rather than by actually performing an
 * exponentiation or a multiplication.
 */

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

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

#ifdef __STDC__
	double scalbn (double x, int n)
#else
	double scalbn (x,n)
	double x; int n;
#endif
{
	int32_t 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;
}
Commit	Line	Data
	1	/* @(#)s_scalbn.c 5.1 93/09/24 */
	2	/*
	3	* ====================================================
	4	* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
	5	*
	6	* Developed at SunPro, a Sun Microsystems, Inc. business.
	7	* Permission to use, copy, modify, and distribute this
	8	* software is freely granted, provided that this notice
	9	* is preserved.
	10	* ====================================================
	11	*/
	12
	13	#if defined(LIBM_SCCS) && !defined(lint)
	14	static char rcsid[] = "$NetBSD: s_scalbn.c,v 1.8 1995/05/10 20:48:08 jtc Exp $";
	15	#endif
	16
	17	/*
	18	* scalbn (double x, int n)
	19	* scalbn(x,n) returns x* 2**n computed by exponent
	20	* manipulation rather than by actually performing an
	21	* exponentiation or a multiplication.
	22	*/
	23
	24	#include "math.h"
	25	#include "math_private.h"
	26
	27	#ifdef __STDC__
	28	static const double
	29	#else
	30	static double
	31	#endif
	32	two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
	33	twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
	34	huge = 1.0e+300,
	35	tiny = 1.0e-300;
	36
	37	#ifdef __STDC__
	38	double scalbn (double x, int n)
	39	#else
	40	double scalbn (x,n)
	41	double x; int n;
	42	#endif
	43	{
	44	int32_t k,hx,lx;
	45	EXTRACT_WORDS(hx,lx,x);
	46	k = (hx&0x7ff00000)>>20; /* extract exponent */
	47	if (k==0) { /* 0 or subnormal x */
	48	if ((lx\|(hx&0x7fffffff))==0) return x; /* +-0 */
	49	x *= two54;
	50	GET_HIGH_WORD(hx,x);
	51	k = ((hx&0x7ff00000)>>20) - 54;
	52	if (n< -50000) return tinyx; /underflow*/
	53	}
	54	if (k==0x7ff) return x+x; /* NaN or Inf */
	55	k = k+n;
	56	if (k > 0x7fe) return hugecopysign(huge,x); / overflow */
	57	if (k > 0) /* normal result */
	58	{SET_HIGH_WORD(x,(hx&0x800fffff)\|(k<<20)); return x;}
	59	if (k <= -54) {
	60	if (n > 50000) /* in case integer overflow in n+k */
	61	return hugecopysign(huge,x); /overflow*/
	62	else return tinycopysign(tiny,x); /underflow*/
	63	}
	64	k += 54; /* subnormal result */
	65	SET_HIGH_WORD(x,(hx&0x800fffff)\|(k<<20));
	66	return x*twom54;
	67	}