xref: /illumos-gate/usr/src/lib/libc/sparc/fp/_Q_ulltoq.c (revision 8119dad84d6416f13557b0ba8e2aaf9064cbcfd3)
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 #include "quad.h"
28 
29 /*
30  * _Q_ulltoq(x) returns (long double)x.
31  */
32 union longdouble
33 _Q_ulltoq(unsigned long long x)
34 {
35 	union longdouble	z;
36 	unsigned int		e;
37 
38 	/* test for zero */
39 	if (x == 0) {
40 		Z.l.msw = Z.l.frac2 = Z.l.frac3 = Z.l.frac4 = 0;
41 		QUAD_RETURN(Z);
42 	}
43 
44 	/* find the most significant bit */
45 	for (e = 63; (x & (1ll << e)) == 0; e--)
46 		;
47 
48 	if (e > 48) {
49 		Z.l.msw = (x >> (e - 16)) & 0xffff;
50 		Z.l.frac2 = x >> (e - 48);
51 		Z.l.frac3 = x << (80 - e);
52 	} else if (e > 16) {
53 		Z.l.msw = (x >> (e - 16)) & 0xffff;
54 		Z.l.frac2 = x << (48 - e);
55 		Z.l.frac3 = 0;
56 	} else {
57 		Z.l.msw = (x << (16 - e)) & 0xffff;
58 		Z.l.frac2 = Z.l.frac3 = 0;
59 	}
60 	Z.l.frac4 = 0;
61 	Z.l.msw |= ((e + 0x3fff) << 16);
62 	QUAD_RETURN(Z);
63 }
64