1 /* Compute remainder and a congruent to the quotient.
2 Copyright (C) 1997-2018 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 "quadmath-imp.h"
22
23 static const __float128 zero = 0.0;
24
25
26 __float128
remquoq(__float128 x,__float128 y,int * quo)27 remquoq (__float128 x, __float128 y, int *quo)
28 {
29 int64_t hx,hy;
30 uint64_t sx,lx,ly,qs;
31 int cquo;
32
33 GET_FLT128_WORDS64 (hx, lx, x);
34 GET_FLT128_WORDS64 (hy, ly, y);
35 sx = hx & 0x8000000000000000ULL;
36 qs = sx ^ (hy & 0x8000000000000000ULL);
37 hy &= 0x7fffffffffffffffLL;
38 hx &= 0x7fffffffffffffffLL;
39
40 /* Purge off exception values. */
41 if ((hy | ly) == 0)
42 return (x * y) / (x * y); /* y = 0 */
43 if ((hx >= 0x7fff000000000000LL) /* x not finite */
44 || ((hy >= 0x7fff000000000000LL) /* y is NaN */
45 && (((hy - 0x7fff000000000000LL) | ly) != 0)))
46 return (x * y) / (x * y);
47
48 if (hy <= 0x7ffbffffffffffffLL)
49 x = fmodq (x, 8 * y); /* now x < 8y */
50
51 if (((hx - hy) | (lx - ly)) == 0)
52 {
53 *quo = qs ? -1 : 1;
54 return zero * x;
55 }
56
57 x = fabsq (x);
58 y = fabsq (y);
59 cquo = 0;
60
61 if (hy <= 0x7ffcffffffffffffLL && x >= 4 * y)
62 {
63 x -= 4 * y;
64 cquo += 4;
65 }
66 if (hy <= 0x7ffdffffffffffffLL && x >= 2 * y)
67 {
68 x -= 2 * y;
69 cquo += 2;
70 }
71
72 if (hy < 0x0002000000000000LL)
73 {
74 if (x + x > y)
75 {
76 x -= y;
77 ++cquo;
78 if (x + x >= y)
79 {
80 x -= y;
81 ++cquo;
82 }
83 }
84 }
85 else
86 {
87 __float128 y_half = 0.5Q * y;
88 if (x > y_half)
89 {
90 x -= y;
91 ++cquo;
92 if (x >= y_half)
93 {
94 x -= y;
95 ++cquo;
96 }
97 }
98 }
99
100 *quo = qs ? -cquo : cquo;
101
102 /* Ensure correct sign of zero result in round-downward mode. */
103 if (x == 0)
104 x = 0;
105 if (sx)
106 x = -x;
107 return x;
108 }
109