xref: /onnv-gate/usr/src/lib/libbc/libc/gen/common/modf.c (revision 0:68f95e015346)
1*0Sstevel@tonic-gate /*
2*0Sstevel@tonic-gate  * CDDL HEADER START
3*0Sstevel@tonic-gate  *
4*0Sstevel@tonic-gate  * The contents of this file are subject to the terms of the
5*0Sstevel@tonic-gate  * Common Development and Distribution License, Version 1.0 only
6*0Sstevel@tonic-gate  * (the "License").  You may not use this file except in compliance
7*0Sstevel@tonic-gate  * with the License.
8*0Sstevel@tonic-gate  *
9*0Sstevel@tonic-gate  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10*0Sstevel@tonic-gate  * or http://www.opensolaris.org/os/licensing.
11*0Sstevel@tonic-gate  * See the License for the specific language governing permissions
12*0Sstevel@tonic-gate  * and limitations under the License.
13*0Sstevel@tonic-gate  *
14*0Sstevel@tonic-gate  * When distributing Covered Code, include this CDDL HEADER in each
15*0Sstevel@tonic-gate  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16*0Sstevel@tonic-gate  * If applicable, add the following below this CDDL HEADER, with the
17*0Sstevel@tonic-gate  * fields enclosed by brackets "[]" replaced with your own identifying
18*0Sstevel@tonic-gate  * information: Portions Copyright [yyyy] [name of copyright owner]
19*0Sstevel@tonic-gate  *
20*0Sstevel@tonic-gate  * CDDL HEADER END
21*0Sstevel@tonic-gate  */
22*0Sstevel@tonic-gate #pragma ident	"%Z%%M%	%I%	%E% SMI"  /* from ATT S5R3 */
23*0Sstevel@tonic-gate 
24*0Sstevel@tonic-gate /*	The following is extracted from...	*/
25*0Sstevel@tonic-gate 
26*0Sstevel@tonic-gate /*	Copyright (c) 1984 AT&T	*/
27*0Sstevel@tonic-gate /*	  All Rights Reserved  	*/
28*0Sstevel@tonic-gate 
29*0Sstevel@tonic-gate 
30*0Sstevel@tonic-gate /*
31*0Sstevel@tonic-gate  * modf(value, iptr) returns the signed fractional part of value
32*0Sstevel@tonic-gate  * and stores the integer part indirectly through iptr.
33*0Sstevel@tonic-gate  *
34*0Sstevel@tonic-gate  */
35*0Sstevel@tonic-gate 
36*0Sstevel@tonic-gate #define MAXPOWTWO	4.503599627370496000E+15
37*0Sstevel@tonic-gate 			/* doubles >= MAXPOWTWO are already integers */
38*0Sstevel@tonic-gate double
modf(value,iptr)39*0Sstevel@tonic-gate modf(value, iptr)
40*0Sstevel@tonic-gate double value;
41*0Sstevel@tonic-gate register double *iptr;
42*0Sstevel@tonic-gate {
43*0Sstevel@tonic-gate 	register double absvalue;
44*0Sstevel@tonic-gate 
45*0Sstevel@tonic-gate 	if ((absvalue = (value >= 0.0) ? value : -value) >= MAXPOWTWO)
46*0Sstevel@tonic-gate 		*iptr = value; /* it must be an integer */
47*0Sstevel@tonic-gate 	else {
48*0Sstevel@tonic-gate 		*iptr = absvalue + MAXPOWTWO; /* shift fraction off right */
49*0Sstevel@tonic-gate 		*iptr -= MAXPOWTWO; /* shift back without fraction */
50*0Sstevel@tonic-gate 		while (*iptr > absvalue) /* above arithmetic might round */
51*0Sstevel@tonic-gate 			*iptr -= 1.0; /* test again just to be sure */
52*0Sstevel@tonic-gate 		if (value < 0.0)
53*0Sstevel@tonic-gate 			*iptr = -*iptr;
54*0Sstevel@tonic-gate 	}
55*0Sstevel@tonic-gate 	return (value - *iptr); /* signed fractional part */
56*0Sstevel@tonic-gate }
57