s_fabsl.c

glibc 库, 不仅可以学习使用库函数,还可以学习函数的具体实现,是提高功力的好资料

/* s_fabsl.c -- long double version of s_fabs.c.
 * Conversion to long double by Ulrich Drepper,
 * 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.
 * ====================================================
 */

#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$NetBSD: $";
#endif

/*
 * fabsl(x) returns the absolute value of x.
 */

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

#ifdef __STDC__
	long double __fabsl(long double x)
#else
	long double __fabsl(x)
	long double x;
#endif
{
	u_int32_t exp;
	GET_LDOUBLE_EXP(exp,x);
	SET_LDOUBLE_EXP(x,exp&0x7fff);
        return x;
}
weak_alias (__fabsl, fabsl)