1/* Compute remainder and a congruent to the quotient.
2 Copyright (C) 1997-2017 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997 and
5 Jakub Jelinek <jj@ultra.linux.cz>, 1999.
6
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public
9 License as published by the Free Software Foundation; either
10 version 2.1 of the License, or (at your option) any later version.
11
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
16
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; if not, see
19 <http://www.gnu.org/licenses/>. */
20
21#include <math.h>
22
23#include <math_private.h>
24
25
26static const _Float128 zero = 0.0;
27
28
29_Float128
30__remquol (_Float128 x, _Float128 y, int *quo)
31{
32 int64_t hx,hy;
33 u_int64_t sx,lx,ly,qs;
34 int cquo;
35
36 GET_LDOUBLE_WORDS64 (hx, lx, x);
37 GET_LDOUBLE_WORDS64 (hy, ly, y);
38 sx = hx & 0x8000000000000000ULL;
39 qs = sx ^ (hy & 0x8000000000000000ULL);
40 hy &= 0x7fffffffffffffffLL;
41 hx &= 0x7fffffffffffffffLL;
42
43 /* Purge off exception values. */
44 if ((hy | ly) == 0)
45 return (x * y) / (x * y); /* y = 0 */
46 if ((hx >= 0x7fff000000000000LL) /* x not finite */
47 || ((hy >= 0x7fff000000000000LL) /* y is NaN */
48 && (((hy - 0x7fff000000000000LL) | ly) != 0)))
49 return (x * y) / (x * y);
50
51 if (hy <= 0x7ffbffffffffffffLL)
52 x = __ieee754_fmodl (x, 8 * y); /* now x < 8y */
53
54 if (((hx - hy) | (lx - ly)) == 0)
55 {
56 *quo = qs ? -1 : 1;
57 return zero * x;
58 }
59
60 x = fabsl (x);
61 y = fabsl (y);
62 cquo = 0;
63
64 if (hy <= 0x7ffcffffffffffffLL && x >= 4 * y)
65 {
66 x -= 4 * y;
67 cquo += 4;
68 }
69 if (hy <= 0x7ffdffffffffffffLL && x >= 2 * y)
70 {
71 x -= 2 * y;
72 cquo += 2;
73 }
74
75 if (hy < 0x0002000000000000LL)
76 {
77 if (x + x > y)
78 {
79 x -= y;
80 ++cquo;
81 if (x + x >= y)
82 {
83 x -= y;
84 ++cquo;
85 }
86 }
87 }
88 else
89 {
90 _Float128 y_half = L(0.5) * y;
91 if (x > y_half)
92 {
93 x -= y;
94 ++cquo;
95 if (x >= y_half)
96 {
97 x -= y;
98 ++cquo;
99 }
100 }
101 }
102
103 *quo = qs ? -cquo : cquo;
104
105 /* Ensure correct sign of zero result in round-downward mode. */
106 if (x == 0)
107 x = 0;
108 if (sx)
109 x = -x;
110 return x;
111}
112weak_alias (__remquol, remquol)
113