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, write to the Free
19 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
20 02111-1307 USA. */
21
22#include "quadmath-imp.h"
23
24
25static const __float128 zero = 0.0;
26
27
28__float128
29remquoq (__float128 x, __float128 y, int *quo)
30{
31 int64_t hx,hy;
32 uint64_t sx,lx,ly,qs;
33 int cquo;
34
35 GET_FLT128_WORDS64 (hx, lx, x);
36 GET_FLT128_WORDS64 (hy, ly, y);
37 sx = hx & 0x8000000000000000ULL;
38 qs = sx ^ (hy & 0x8000000000000000ULL);
39 hy &= 0x7fffffffffffffffLL;
40 hx &= 0x7fffffffffffffffLL;
41
42 /* Purge off exception values. */
43 if ((hy | ly) == 0)
44 return (x * y) / (x * y); /* y = 0 */
45 if ((hx >= 0x7fff000000000000LL) /* x not finite */
46 || ((hy >= 0x7fff000000000000LL) /* y is NaN */
47 && (((hy - 0x7fff000000000000LL) | ly) != 0)))
48 return (x * y) / (x * y);
49
50 if (hy <= 0x7ffbffffffffffffLL)
51 x = fmodq (x, 8 * y); /* now x < 8y */
52
53 if (((hx - hy) | (lx - ly)) == 0)
54 {
55 *quo = qs ? -1 : 1;
56 return zero * x;
57 }
58
59 x = fabsq (x);
60 y = fabsq (y);
61 cquo = 0;
62
63 if (hy <= 0x7ffcffffffffffffLL && x >= 4 * y)
64 {
65 x -= 4 * y;
66 cquo += 4;
67 }
68 if (hy <= 0x7ffdffffffffffffLL && x >= 2 * y)
69 {
70 x -= 2 * y;
71 cquo += 2;
72 }
73
74 if (hy < 0x0002000000000000LL)
75 {
76 if (x + x > y)
77 {
78 x -= y;
79 ++cquo;
80 if (x + x >= y)
81 {
82 x -= y;
83 ++cquo;
84 }
85 }
86 }
87 else
88 {
89 __float128 y_half = 0.5Q * y;
90 if (x > y_half)
91 {
92 x -= y;
93 ++cquo;
94 if (x >= y_half)
95 {
96 x -= y;
97 ++cquo;
98 }
99 }
100 }
101
102 *quo = qs ? -cquo : cquo;
103
104 /* Ensure correct sign of zero result in round-downward mode. */
105 if (x == 0.0Q)
106 x = 0.0Q;
107 if (sx)
108 x = -x;
109 return x;
110}
111