1 | /* Compute remainder and a congruent to the quotient. |
2 | Copyright (C) 1997-2022 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <https://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <math.h> |
20 | |
21 | #include <math_private.h> |
22 | #include <math_ldbl_opt.h> |
23 | |
24 | |
25 | static const long double zero = 0.0; |
26 | |
27 | |
28 | long double |
29 | __remquol (long double x, long double y, int *quo) |
30 | { |
31 | int64_t hx,hy; |
32 | uint64_t sx,lx,ly,qs; |
33 | int cquo; |
34 | double xhi, xlo, yhi, ylo; |
35 | |
36 | ldbl_unpack (x, &xhi, &xlo); |
37 | EXTRACT_WORDS64 (hx, xhi); |
38 | EXTRACT_WORDS64 (lx, xlo); |
39 | ldbl_unpack (y, &yhi, &ylo); |
40 | EXTRACT_WORDS64 (hy, yhi); |
41 | EXTRACT_WORDS64 (ly, ylo); |
42 | sx = hx & 0x8000000000000000ULL; |
43 | qs = sx ^ (hy & 0x8000000000000000ULL); |
44 | ly ^= hy & 0x8000000000000000ULL; |
45 | hy &= 0x7fffffffffffffffLL; |
46 | lx ^= sx; |
47 | hx &= 0x7fffffffffffffffLL; |
48 | |
49 | /* Purge off exception values. */ |
50 | if (hy == 0) |
51 | return (x * y) / (x * y); /* y = 0 */ |
52 | if ((hx >= 0x7ff0000000000000LL) /* x not finite */ |
53 | || (hy > 0x7ff0000000000000LL)) /* y is NaN */ |
54 | return (x * y) / (x * y); |
55 | |
56 | if (hy <= 0x7fbfffffffffffffLL) |
57 | x = __ieee754_fmodl (x, 8 * y); /* now x < 8y */ |
58 | |
59 | if (((hx - hy) | (lx - ly)) == 0) |
60 | { |
61 | *quo = qs ? -1 : 1; |
62 | return zero * x; |
63 | } |
64 | |
65 | x = fabsl (x: x); |
66 | y = fabsl (x: y); |
67 | cquo = 0; |
68 | |
69 | if (hy <= 0x7fcfffffffffffffLL && x >= 4 * y) |
70 | { |
71 | x -= 4 * y; |
72 | cquo += 4; |
73 | } |
74 | if (hy <= 0x7fdfffffffffffffLL && x >= 2 * y) |
75 | { |
76 | x -= 2 * y; |
77 | cquo += 2; |
78 | } |
79 | |
80 | if (hy < 0x0020000000000000LL) |
81 | { |
82 | if (x + x > y) |
83 | { |
84 | x -= y; |
85 | ++cquo; |
86 | if (x + x >= y) |
87 | { |
88 | x -= y; |
89 | ++cquo; |
90 | } |
91 | } |
92 | } |
93 | else |
94 | { |
95 | long double y_half = 0.5L * y; |
96 | if (x > y_half) |
97 | { |
98 | x -= y; |
99 | ++cquo; |
100 | if (x >= y_half) |
101 | { |
102 | x -= y; |
103 | ++cquo; |
104 | } |
105 | } |
106 | } |
107 | |
108 | *quo = qs ? -cquo : cquo; |
109 | |
110 | /* Ensure correct sign of zero result in round-downward mode. */ |
111 | if (x == 0.0L) |
112 | x = 0.0L; |
113 | if (sx) |
114 | x = -x; |
115 | return x; |
116 | } |
117 | long_double_symbol (libm, __remquol, remquol); |
118 | |