1 /* $NetBSD: floatundidf_ieee754.c,v 1.2 2013/09/30 19:32:14 mlelstv Exp $ */
2
3 /*-
4 * Copyright (c) 2013 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Matt Thomas of 3am Software Foundry.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 #if defined(LIBC_SCCS) && !defined(lint)
34 __RCSID("$NetBSD: floatundidf_ieee754.c,v 1.2 2013/09/30 19:32:14 mlelstv Exp $");
35 #endif /* LIBC_SCCS and not lint */
36
37 #if defined(SOFTFLOAT) || defined(__ARM_EABI__)
38 #include "softfloat/softfloat-for-gcc.h"
39 #endif
40
41 #include <limits.h>
42 #include <machine/ieee.h>
43 #include "quad.h"
44
45 /*
46 * Convert unsigned quad to double.
47 */
48 double
__floatundidf(u_quad_t x)49 __floatundidf(u_quad_t x)
50 {
51 union ieee_double_u ux = { .dblu_d = 0.0 };
52
53 if (x == 0)
54 return 0.0;
55
56 u_int l = __builtin_clzll(x);
57 x <<= (l + 1); /* clear implicit bit */
58 x >>= 64 - (DBL_FRACHBITS + DBL_FRACLBITS);
59 union uu u = { .uq = x };
60 ux.dblu_frach = u.ul[H];
61 ux.dblu_fracl = u.ul[L];
62 ux.dblu_exp = DBL_EXP_BIAS + 63 - l;
63
64 return ux.dblu_d;
65 }
66