1 /* $NetBSD: floatdidf.c,v 1.10 2013/02/03 01:48:53 matt Exp $ */
2
3 /*-
4 * Copyright (c) 1992, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This software was developed by the Computer Systems Engineering group
8 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9 * contributed to Berkeley.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 #include <sys/cdefs.h>
37 #if defined(LIBC_SCCS) && !defined(lint)
38 #if 0
39 static char sccsid[] = "@(#)floatdidf.c 8.1 (Berkeley) 6/4/93";
40 #else
41 __RCSID("$NetBSD: floatdidf.c,v 1.10 2013/02/03 01:48:53 matt Exp $");
42 #endif
43 #endif /* LIBC_SCCS and not lint */
44
45 #if defined(SOFTFLOAT) || defined(__ARM_EABI__)
46 #include "softfloat/softfloat-for-gcc.h"
47 #endif
48
49 #include "quad.h"
50
51 /*
52 * Convert (signed) quad to double.
53 */
54 double
__floatdidf(quad_t x)55 __floatdidf(quad_t x)
56 {
57 double d;
58 union uu u;
59 int neg;
60
61 /*
62 * Get an unsigned number first, by negating if necessary.
63 */
64 if (x < 0)
65 u.q = -x, neg = 1;
66 else
67 u.q = x, neg = 0;
68
69 /*
70 * Now u.ul[H] has the factor of 2^32 (or whatever) and u.ul[L]
71 * has the units. Ideally we could just set d, add INT_BITS to
72 * its exponent, and then add the units, but this is portable
73 * code and does not know how to get at an exponent. Machine-
74 * specific code may be able to do this more efficiently.
75 */
76 d = (double)u.ul[H] * (((int)1 << (unsigned int)(INT_BITS - 2)) * 4.0);
77 d += u.ul[L];
78
79 return (neg ? -d : d);
80 }
81