xref: /illumos-gate/usr/src/lib/libc/sparc/fp/_Q_lltoq.c (revision 7c478bd9)
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_lltoq(x) returns (long double)x.
33  */
34 union longdouble
_Q_lltoq(long long x)35 _Q_lltoq(long long x)
36 {
37 	union longdouble	z;
38 	unsigned int		s, e;
39 
40 	/* extract the sign */
41 	s = 0;
42 	if (x < 0) {
43 		if ((unsigned long long) x == 0x8000000000000000ull) {
44 			/* largest negative 64 bit int */
45 			Z.l.msw = 0xc03e0000;
46 			Z.l.frac2 = Z.l.frac3 = Z.l.frac4 = 0;
47 			QUAD_RETURN(Z);
48 		}
49 		x = -x;
50 		s = 0x80000000;
51 	} else if (x == 0) {
52 		Z.l.msw = Z.l.frac2 = Z.l.frac3 = Z.l.frac4 = 0;
53 		QUAD_RETURN(Z);
54 	}
55 
56 	/* find the most significant bit */
57 	for (e = 62; (x & (1ll << e)) == 0; e--)
58 		;
59 
60 	if (e > 48) {
61 		Z.l.msw = ((unsigned long long) x >> (e - 16)) & 0xffff;
62 		Z.l.frac2 = (unsigned long long) x >> (e - 48);
63 		Z.l.frac3 = (unsigned long long) x << (80 - e);
64 	} else if (e > 16) {
65 		Z.l.msw = ((unsigned long long) x >> (e - 16)) & 0xffff;
66 		Z.l.frac2 = (unsigned long long) x << (48 - e);
67 		Z.l.frac3 = 0;
68 	} else {
69 		Z.l.msw = ((unsigned long long) x << (16 - e)) & 0xffff;
70 		Z.l.frac2 = Z.l.frac3 = 0;
71 	}
72 	Z.l.frac4 = 0;
73 	Z.l.msw |= s | ((e + 0x3fff) << 16);
74 	QUAD_RETURN(Z);
75 }
76