1 /* $NetBSD: floatdisf_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: floatdisf_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 <limits.h>
42 #include <machine/ieee.h>
43 #include "quad.h"
44
45 float __floatdisf(quad_t);
46
47 /*
48 * Convert signed quad to float.
49 */
50 float
__floatdisf(quad_t x)51 __floatdisf(quad_t x)
52 {
53 union ieee_single_u ux = { .sngu_f = 0.0 };
54
55 if (x == 0)
56 return 0.0;
57 if (x == 1)
58 return 1.0;
59
60 if (x < 0) {
61 if (x == QUAD_MIN)
62 return -0x1.0p63;
63 ux.sngu_sign = 1;
64 x = -x;
65 }
66 #if defined(_LP64) || defined(__mips_n32)
67 u_int l = __builtin_clzll(x);
68 x <<= (l + 1); /* clear implicit bit */
69
70 ux.sngu_frac = (u_quad_t)x >> (64 - SNG_FRACBITS);
71 #else
72 union uu u = { .uq = x };
73 uint32_t frac;
74 u_int l;
75 if (u.ul[H] == 0) {
76 l = __builtin_clz(u.ul[L]);
77 frac = u.ul[L] << (l + 1); /* clear implicit bit */
78 l += 32;
79 } else {
80 l = __builtin_clz(u.ul[H]);
81 frac = u.ul[H] << (l + 1); /* clear implicit bit */
82 frac |= u.ul[L] >> (32 - (l + 1));
83 }
84
85 ux.sngu_frac = frac >> (32 - SNG_FRACBITS);
86 #endif
87 ux.sngu_exp = SNG_EXP_BIAS + 63 - l;
88
89 return ux.sngu_f;
90 }
91