1 /* $NetBSD: floatunditf_ieee754.c,v 1.1 2014/01/30 15:06:18 joerg Exp $ */
2
3 /*-
4 * Copyright (c) 2014 Joerg Sonnenberger <joerg@NetBSD.org>.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
16 * distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
21 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
22 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
24 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
25 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
26 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
27 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
28 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __RCSID("$NetBSD: floatunditf_ieee754.c,v 1.1 2014/01/30 15:06:18 joerg Exp $");
34
35 #include <math.h>
36 #include <machine/ieee.h>
37 #include <limits.h>
38
39 #ifdef __HAVE_LONG_DOUBLE
40
41 long double __floatunditf(uint64_t x);
42
43 /*
44 * Convert uint64_t to long double.
45 */
46 long double
__floatunditf(uint64_t x)47 __floatunditf(uint64_t x)
48 {
49 int exponent, zeros;
50 union ieee_ext_u ux;
51
52 /* Use the easier conversion routine for uint32_t if possible. */
53 if (x <= UINT32_MAX)
54 return (long double)(uint32_t)x;
55
56 zeros = __builtin_clzll(x);
57 #ifdef LDBL_IMPLICIT_NBIT
58 exponent = 64 - zeros;
59 x <<= zeros + 1;
60 #else
61 exponent = 63 - zeros;
62 x <<= zeros;
63 #endif
64
65 ux.extu_exp = EXT_EXP_BIAS + exponent;
66 ux.extu_frach = (x >> (64 - EXT_FRACHBITS));
67 x <<= EXT_FRACHBITS;
68 #ifdef EXT_FRACHMBITS
69 ux.extu_frachm = (x >> (64 - EXT_FRACHMBITS));
70 x <<= EXT_FRACHMBITS;
71 #endif
72 #ifdef EXT_FRACLMBITS
73 ux.extu_fraclm = (x >> (64 - EXT_FRACLMBITS));
74 x <<= EXT_FRACLMBITS;
75 #endif
76 ux.extu_fracl = (x >> (64 - EXT_FRACLBITS));
77 ux.extu_sign = 0;
78
79 return ux.extu_ld;
80 }
81 #endif /* __HAVE_LONG_DOUBLE */
82