1 /* $NetBSD: floatundisf_ieee754.c,v 1.2 2013/08/24 00:51:48 matt 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: floatundisf_ieee754.c,v 1.2 2013/08/24 00:51:48 matt 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 <machine/ieee.h>
42 #include "quad.h"
43
44 float __floatundisf(u_quad_t);
45
46 /*
47 * Convert unsigned quad to float.
48 */
49 float
__floatundisf(u_quad_t x)50 __floatundisf(u_quad_t x)
51 {
52 union ieee_single_u ux = { .sngu_f = 0.0 };
53
54 if (x == 0)
55 return 0.0;
56 if (x == 1)
57 return 1.0;
58
59 #if defined(_LP64) || defined(__mips_n32)
60 u_int l = __builtin_clzll(x);
61 x <<= (l + 1); /* clear implicit bit */
62
63 ux.sngu_frac = x >> (64 - SNG_FRACBITS);
64 #else
65 union uu u = { .uq = x };
66 uint32_t frac;
67 u_int l;
68 if (u.ul[H] == 0) {
69 l = __builtin_clz(u.ul[L]);
70 frac = u.ul[L] << (l + 1); /* clear implicit bit */
71 l += 32;
72 } else {
73 l = __builtin_clz(u.ul[H]);
74 frac = u.ul[H] << (l + 1); /* clear implicit bit */
75 frac |= u.ul[L] >> (32 - (l + 1));
76 }
77
78 ux.sngu_frac = frac >> (32 - SNG_FRACBITS);
79 #endif
80 ux.sngu_exp = SNG_EXP_BIAS + 63 - l;
81
82 return ux.sngu_f;
83 }
84