xref: /illumos-gate/usr/src/lib/libc/sparcv9/fp/_Qp_xtoq.c (revision 9b9d39d2a32ff806d2431dbcc50968ef1e6d46b2)
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  * _Qp_xtoq(pz, x) sets *pz = (long double)x.
31  */
32 void
33 _Qp_xtoq(union longdouble *pz, long x)
34 {
35 	unsigned int	s, e;
36 
37 	/* extract the sign */
38 	s = 0;
39 	if (x < 0) {
40 		if ((unsigned long) x == 0x8000000000000000ul) {
41 			/* largest negative 64 bit int */
42 			Z.l.msw = 0xc03e0000;
43 			Z.l.frac2 = Z.l.frac3 = Z.l.frac4 = 0;
44 			QUAD_RETURN(Z);
45 		}
46 		x = -x;
47 		s = 0x80000000;
48 	} else if (x == 0) {
49 		Z.l.msw = Z.l.frac2 = Z.l.frac3 = Z.l.frac4 = 0;
50 		QUAD_RETURN(Z);
51 	}
52 
53 	/* find the most significant bit */
54 	for (e = 62; (x & (1l << e)) == 0; e--)
55 		;
56 
57 	if (e > 48) {
58 		Z.l.msw = ((unsigned long) x >> (e - 16)) & 0xffff;
59 		Z.l.frac2 = (unsigned long) x >> (e - 48);
60 		Z.l.frac3 = (unsigned long) x << (80 - e);
61 	} else if (e > 16) {
62 		Z.l.msw = ((unsigned long) x >> (e - 16)) & 0xffff;
63 		Z.l.frac2 = (unsigned long) x << (48 - e);
64 		Z.l.frac3 = 0;
65 	} else {
66 		Z.l.msw = ((unsigned long) x << (16 - e)) & 0xffff;
67 		Z.l.frac2 = Z.l.frac3 = 0;
68 	}
69 	Z.l.frac4 = 0;
70 	Z.l.msw |= s | ((e + 0x3fff) << 16);
71 	QUAD_RETURN(Z);
72 }
73