xref: /illumos-gate/usr/src/lib/libc/sparc/fp/_Q_ulltoq.c (revision 8b80e8cb6855118d46f605e91b5ed4ce83417395)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright (c) 1994-1997, by Sun Microsystems, Inc.
24  * All rights reserved.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 #include "quad.h"
30 
31 /*
32  * _Q_ulltoq(x) returns (long double)x.
33  */
34 union longdouble
35 _Q_ulltoq(unsigned long long x)
36 {
37 	union longdouble	z;
38 	unsigned int		e;
39 
40 	/* test for zero */
41 	if (x == 0) {
42 		Z.l.msw = Z.l.frac2 = Z.l.frac3 = Z.l.frac4 = 0;
43 		QUAD_RETURN(Z);
44 	}
45 
46 	/* find the most significant bit */
47 	for (e = 63; (x & (1ll << e)) == 0; e--)
48 		;
49 
50 	if (e > 48) {
51 		Z.l.msw = (x >> (e - 16)) & 0xffff;
52 		Z.l.frac2 = x >> (e - 48);
53 		Z.l.frac3 = x << (80 - e);
54 	} else if (e > 16) {
55 		Z.l.msw = (x >> (e - 16)) & 0xffff;
56 		Z.l.frac2 = x << (48 - e);
57 		Z.l.frac3 = 0;
58 	} else {
59 		Z.l.msw = (x << (16 - e)) & 0xffff;
60 		Z.l.frac2 = Z.l.frac3 = 0;
61 	}
62 	Z.l.frac4 = 0;
63 	Z.l.msw |= ((e + 0x3fff) << 16);
64 	QUAD_RETURN(Z);
65 }
66