e_scalb.c

来自「在x86平台上运行不可信任代码的sandbox。」· C语言 代码 · 共 48 行

/* @(#)e_scalb.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.
 * ====================================================
 */

#ifndef lint
static char rcsid[] = "$FreeBSD: src/lib/msun/src/e_scalb.c,v 1.11 2004/07/09 10:01:10 das Exp $";
#endif

/*
 * __ieee754_scalb(x, fn) is provide for
 * passing various standard test suite. One
 * should use scalbn() instead.
 */

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

#ifdef _SCALB_INT
double
__ieee754_scalb(double x, int fn)
#else
double
__ieee754_scalb(double x, double fn)
#endif
{
#ifdef _SCALB_INT
	return scalbn(x,fn);
#else
	if ((isnan)(x)||(isnan)(fn)) return x*fn;
	if (!finite(fn)) {
	    if(fn>0.0) return x*fn;
	    else       return x/(-fn);
	}
	if (rint(fn)!=fn) return (fn-fn)/(fn-fn);
	if ( fn > 65000.0) return scalbn(x, 65000);
	if (-fn > 65000.0) return scalbn(x,-65000);
	return scalbn(x,(int)fn);
#endif
}