[BACK]Return to s_floor.c CVS log [TXT][DIR] Up to [cvs.NetBSD.org] / src / lib / libm / src

File: [cvs.NetBSD.org] / src / lib / libm / src / s_floor.c (download)

Revision 1.9, Thu Oct 9 11:32:01 1997 UTC (21 years, 2 months ago) by lukem
Branch: MAIN
CVS Tags: netbsd-1-4-base, netbsd-1-4-RELEASE, netbsd-1-4-PATCH003, netbsd-1-4-PATCH002, netbsd-1-4-PATCH001, netbsd-1-4, netbsd-1-3-base, netbsd-1-3-RELEASE, netbsd-1-3-PATCH003-CANDIDATE2, netbsd-1-3-PATCH003-CANDIDATE1, netbsd-1-3-PATCH003-CANDIDATE0, netbsd-1-3-PATCH003, netbsd-1-3-PATCH002, netbsd-1-3-PATCH001, netbsd-1-3-BETA, netbsd-1-3
Changes since 1.8: +2 -1 lines

rcsid facism, WARNSify

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

#include <sys/cdefs.h>
#if defined(LIBM_SCCS) && !defined(lint)
__RCSID("$NetBSD: s_floor.c,v 1.9 1997/10/09 11:32:01 lukem Exp $");
#endif

/*
 * floor(x)
 * Return x rounded toward -inf to integral value
 * Method:
 *	Bit twiddling.
 * Exception:
 *	Inexact flag raised if x not equal to floor(x).
 */

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

#ifdef __STDC__
static const double huge = 1.0e300;
#else
static double huge = 1.0e300;
#endif

#ifdef __STDC__
	double floor(double x)
#else
	double floor(x)
	double x;
#endif
{
	int32_t i0,i1,j0;
	u_int32_t i,j;
	EXTRACT_WORDS(i0,i1,x);
	j0 = ((i0>>20)&0x7ff)-0x3ff;
	if(j0<20) {
	    if(j0<0) { 	/* raise inexact if x != 0 */
		if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
		    if(i0>=0) {i0=i1=0;} 
		    else if(((i0&0x7fffffff)|i1)!=0)
			{ i0=0xbff00000;i1=0;}
		}
	    } else {
		i = (0x000fffff)>>j0;
		if(((i0&i)|i1)==0) return x; /* x is integral */
		if(huge+x>0.0) {	/* raise inexact flag */
		    if(i0<0) i0 += (0x00100000)>>j0;
		    i0 &= (~i); i1=0;
		}
	    }
	} else if (j0>51) {
	    if(j0==0x400) return x+x;	/* inf or NaN */
	    else return x;		/* x is integral */
	} else {
	    i = ((u_int32_t)(0xffffffff))>>(j0-20);
	    if((i1&i)==0) return x;	/* x is integral */
	    if(huge+x>0.0) { 		/* raise inexact flag */
		if(i0<0) {
		    if(j0==20) i0+=1; 
		    else {
			j = i1+(1<<(52-j0));
			if(j<i1) i0 +=1 ; 	/* got a carry */
			i1=j;
		    }
		}
		i1 &= (~i);
	    }
	}
	INSERT_WORDS(x,i0,i1);
	return x;
}