w_logf.c

来自「在x86平台上运行不可信任代码的sandbox。」· C语言 代码 · 共 45 行

/* w_logf.c -- float version of w_log.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_logf.c,v 1.7 2002/05/28 18:15:04 alfred Exp $";
#endif

/*
 * wrapper logf(x)
 */

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


float
logf(float x)		/* wrapper logf */
{
#ifdef _IEEE_LIBM
	return __ieee754_logf(x);
#else
	float z;
	z = __ieee754_logf(x);
	if(_LIB_VERSION == _IEEE_ || isnanf(x) || x > (float)0.0) return z;
	if(x==(float)0.0)
	    /* logf(0) */
	    return (float)__kernel_standard((double)x,(double)x,116);
	else
	    /* logf(x<0) */
	    return (float)__kernel_standard((double)x,(double)x,117);
#endif
}