xref: /titanic_52/usr/src/lib/libbc/libc/gen/common/modf.c (revision 7c478bd95313f5f23a4c958a745db2134aa03244)
1*7c478bd9Sstevel@tonic-gate /*
2*7c478bd9Sstevel@tonic-gate  * CDDL HEADER START
3*7c478bd9Sstevel@tonic-gate  *
4*7c478bd9Sstevel@tonic-gate  * The contents of this file are subject to the terms of the
5*7c478bd9Sstevel@tonic-gate  * Common Development and Distribution License, Version 1.0 only
6*7c478bd9Sstevel@tonic-gate  * (the "License").  You may not use this file except in compliance
7*7c478bd9Sstevel@tonic-gate  * with the License.
8*7c478bd9Sstevel@tonic-gate  *
9*7c478bd9Sstevel@tonic-gate  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10*7c478bd9Sstevel@tonic-gate  * or http://www.opensolaris.org/os/licensing.
11*7c478bd9Sstevel@tonic-gate  * See the License for the specific language governing permissions
12*7c478bd9Sstevel@tonic-gate  * and limitations under the License.
13*7c478bd9Sstevel@tonic-gate  *
14*7c478bd9Sstevel@tonic-gate  * When distributing Covered Code, include this CDDL HEADER in each
15*7c478bd9Sstevel@tonic-gate  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16*7c478bd9Sstevel@tonic-gate  * If applicable, add the following below this CDDL HEADER, with the
17*7c478bd9Sstevel@tonic-gate  * fields enclosed by brackets "[]" replaced with your own identifying
18*7c478bd9Sstevel@tonic-gate  * information: Portions Copyright [yyyy] [name of copyright owner]
19*7c478bd9Sstevel@tonic-gate  *
20*7c478bd9Sstevel@tonic-gate  * CDDL HEADER END
21*7c478bd9Sstevel@tonic-gate  */
22*7c478bd9Sstevel@tonic-gate #pragma ident	"%Z%%M%	%I%	%E% SMI"  /* from ATT S5R3 */
23*7c478bd9Sstevel@tonic-gate 
24*7c478bd9Sstevel@tonic-gate /*	The following is extracted from...	*/
25*7c478bd9Sstevel@tonic-gate 
26*7c478bd9Sstevel@tonic-gate /*	Copyright (c) 1984 AT&T	*/
27*7c478bd9Sstevel@tonic-gate /*	  All Rights Reserved  	*/
28*7c478bd9Sstevel@tonic-gate 
29*7c478bd9Sstevel@tonic-gate 
30*7c478bd9Sstevel@tonic-gate /*
31*7c478bd9Sstevel@tonic-gate  * modf(value, iptr) returns the signed fractional part of value
32*7c478bd9Sstevel@tonic-gate  * and stores the integer part indirectly through iptr.
33*7c478bd9Sstevel@tonic-gate  *
34*7c478bd9Sstevel@tonic-gate  */
35*7c478bd9Sstevel@tonic-gate 
36*7c478bd9Sstevel@tonic-gate #define MAXPOWTWO	4.503599627370496000E+15
37*7c478bd9Sstevel@tonic-gate 			/* doubles >= MAXPOWTWO are already integers */
38*7c478bd9Sstevel@tonic-gate double
39*7c478bd9Sstevel@tonic-gate modf(value, iptr)
40*7c478bd9Sstevel@tonic-gate double value;
41*7c478bd9Sstevel@tonic-gate register double *iptr;
42*7c478bd9Sstevel@tonic-gate {
43*7c478bd9Sstevel@tonic-gate 	register double absvalue;
44*7c478bd9Sstevel@tonic-gate 
45*7c478bd9Sstevel@tonic-gate 	if ((absvalue = (value >= 0.0) ? value : -value) >= MAXPOWTWO)
46*7c478bd9Sstevel@tonic-gate 		*iptr = value; /* it must be an integer */
47*7c478bd9Sstevel@tonic-gate 	else {
48*7c478bd9Sstevel@tonic-gate 		*iptr = absvalue + MAXPOWTWO; /* shift fraction off right */
49*7c478bd9Sstevel@tonic-gate 		*iptr -= MAXPOWTWO; /* shift back without fraction */
50*7c478bd9Sstevel@tonic-gate 		while (*iptr > absvalue) /* above arithmetic might round */
51*7c478bd9Sstevel@tonic-gate 			*iptr -= 1.0; /* test again just to be sure */
52*7c478bd9Sstevel@tonic-gate 		if (value < 0.0)
53*7c478bd9Sstevel@tonic-gate 			*iptr = -*iptr;
54*7c478bd9Sstevel@tonic-gate 	}
55*7c478bd9Sstevel@tonic-gate 	return (value - *iptr); /* signed fractional part */
56*7c478bd9Sstevel@tonic-gate }
57