w_expf.c

在x86平台上运行不可信任代码的sandbox。

/* w_expf.c -- float version of w_exp.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, [e-mail].
 */

/*
 * ====================================================
 * 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/w_expf.c,v 1.7 2002/05/28 18:15:04 alfred Exp $";
#endif

/*
 * wrapper expf(x)
 */

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

static const float
o_threshold=  8.8721679688e+01,  /* 0x42b17180 */
u_threshold= -1.0397208405e+02;  /* 0xc2cff1b5 */

float
expf(float x)		/* wrapper expf */
{
#ifdef _IEEE_LIBM
	return __ieee754_expf(x);
#else
	float z;
	z = __ieee754_expf(x);
	if(_LIB_VERSION == _IEEE_) return z;
	if(finitef(x)) {
	    if(x>o_threshold)
	        /* exp overflow */
	        return (float)__kernel_standard((double)x,(double)x,106);
	    else if(x<u_threshold)
	        /* exp underflow */
	        return (float)__kernel_standard((double)x,(double)x,107);
	}
	return z;
#endif
}