xref: /illumos-gate/usr/src/lib/libc/sparc/fp/_Q_lltoq.c (revision 201ceb75ab95f9bf1f42ea1dc9ab363b43ba47cf)
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_lltoq(x) returns (long double)x.
31  */
32 union longdouble
33 _Q_lltoq(long long x)
34 {
35 	union longdouble	z;
36 	unsigned int		s, e;
37 
38 	/* extract the sign */
39 	s = 0;
40 	if (x < 0) {
41 		if ((unsigned long long) x == 0x8000000000000000ull) {
42 			/* largest negative 64 bit int */
43 			Z.l.msw = 0xc03e0000;
44 			Z.l.frac2 = Z.l.frac3 = Z.l.frac4 = 0;
45 			QUAD_RETURN(Z);
46 		}
47 		x = -x;
48 		s = 0x80000000;
49 	} else if (x == 0) {
50 		Z.l.msw = Z.l.frac2 = Z.l.frac3 = Z.l.frac4 = 0;
51 		QUAD_RETURN(Z);
52 	}
53 
54 	/* find the most significant bit */
55 	for (e = 62; (x & (1ll << e)) == 0; e--)
56 		;
57 
58 	if (e > 48) {
59 		Z.l.msw = ((unsigned long long) x >> (e - 16)) & 0xffff;
60 		Z.l.frac2 = (unsigned long long) x >> (e - 48);
61 		Z.l.frac3 = (unsigned long long) x << (80 - e);
62 	} else if (e > 16) {
63 		Z.l.msw = ((unsigned long long) x >> (e - 16)) & 0xffff;
64 		Z.l.frac2 = (unsigned long long) x << (48 - e);
65 		Z.l.frac3 = 0;
66 	} else {
67 		Z.l.msw = ((unsigned long long) x << (16 - e)) & 0xffff;
68 		Z.l.frac2 = Z.l.frac3 = 0;
69 	}
70 	Z.l.frac4 = 0;
71 	Z.l.msw |= s | ((e + 0x3fff) << 16);
72 	QUAD_RETURN(Z);
73 }
74