Branch data Line data Source code
1 : : /*-
2 : : * Copyright (c) 2007 David Schultz <das@FreeBSD.ORG>
3 : : * All rights reserved.
4 : : *
5 : : * Redistribution and use in source and binary forms, with or without
6 : : * modification, are permitted provided that the following conditions
7 : : * are met:
8 : : * 1. Redistributions of source code must retain the above copyright
9 : : * notice, this list of conditions and the following disclaimer.
10 : : * 2. Redistributions in binary form must reproduce the above copyright
11 : : * notice, this list of conditions and the following disclaimer in the
12 : : * documentation and/or other materials provided with the distribution.
13 : : *
14 : : * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 : : * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 : : * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 : : * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 : : * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 : : * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 : : * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 : : * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 : : * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 : : * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 : : * SUCH DAMAGE.
25 : : *
26 : : * Derived from s_modf.c, which has the following Copyright:
27 : : * ====================================================
28 : : * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
29 : : *
30 : : * Developed at SunPro, a Sun Microsystems, Inc. business.
31 : : * Permission to use, copy, modify, and distribute this
32 : : * software is freely granted, provided that this notice
33 : : * is preserved.
34 : : * ====================================================
35 : : *
36 : : * $FreeBSD: src/lib/msun/src/s_modfl.c,v 1.1 2007/01/07 07:54:21 das Exp $
37 : : */
38 : :
39 : : #include <float.h>
40 : : #include <openlibm_math.h>
41 : :
42 : : #include "fpmath.h"
43 : : #include "math_private.h"
44 : :
45 : : #if LDBL_MANL_SIZE > 32
46 : : #define MASK ((u_int64_t)-1)
47 : : #else
48 : : #define MASK ((u_int32_t)-1)
49 : : #endif
50 : : /* Return the last n bits of a word, representing the fractional part. */
51 : : #define GETFRAC(bits, n) ((bits) & ~(MASK << (n)))
52 : : /* The number of fraction bits in manh, not counting the integer bit */
53 : : #define HIBITS (LDBL_MANT_DIG - LDBL_MANL_SIZE)
54 : :
55 : : static const long double zero[] = { 0.0L, -0.0L };
56 : :
57 : : OLM_DLLEXPORT long double
58 : 0 : modfl(long double x, long double *iptr)
59 : : {
60 : : union IEEEl2bits ux;
61 : : int e;
62 : :
63 : 0 : ux.e = x;
64 : 0 : e = ux.bits.exp - LDBL_MAX_EXP + 1;
65 [ # # ]: 0 : if (e < HIBITS) { /* Integer part is in manh. */
66 [ # # ]: 0 : if (e < 0) { /* |x|<1 */
67 : 0 : *iptr = zero[ux.bits.sign];
68 : 0 : return (x);
69 : : } else {
70 : 0 : if ((GETFRAC(ux.bits.manh, HIBITS - 1 - e) |
71 [ # # ]: 0 : ux.bits.manl) == 0) { /* X is an integer. */
72 : 0 : *iptr = x;
73 : 0 : return (zero[ux.bits.sign]);
74 : : } else {
75 : : /* Clear all but the top e+1 bits. */
76 : 0 : ux.bits.manh >>= HIBITS - 1 - e;
77 : 0 : ux.bits.manh <<= HIBITS - 1 - e;
78 : 0 : ux.bits.manl = 0;
79 : 0 : *iptr = ux.e;
80 : 0 : return (x - ux.e);
81 : : }
82 : : }
83 [ # # ]: 0 : } else if (e >= LDBL_MANT_DIG - 1) { /* x has no fraction part. */
84 : 0 : *iptr = x;
85 [ # # ]: 0 : if (x != x) /* Handle NaNs. */
86 : 0 : return (x);
87 : 0 : return (zero[ux.bits.sign]);
88 : : } else { /* Fraction part is in manl. */
89 [ # # ]: 0 : if (GETFRAC(ux.bits.manl, LDBL_MANT_DIG - 1 - e) == 0) {
90 : : /* x is integral. */
91 : 0 : *iptr = x;
92 : 0 : return (zero[ux.bits.sign]);
93 : : } else {
94 : : /* Clear all but the top e+1 bits. */
95 : 0 : ux.bits.manl >>= LDBL_MANT_DIG - 1 - e;
96 : 0 : ux.bits.manl <<= LDBL_MANT_DIG - 1 - e;
97 : 0 : *iptr = ux.e;
98 : 0 : return (x - ux.e);
99 : : }
100 : : }
101 : : }
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