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bb3129bd | 1 | /* Compute remainder and a congruent to the quotient. |
04277e02 | 2 | Copyright (C) 1997-2019 Free Software Foundation, Inc. |
bb3129bd UD |
3 | This file is part of the GNU C Library. |
4 | Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997. | |
5 | ||
6 | The GNU C Library is free software; you can redistribute it and/or | |
7 | modify it under the terms of the GNU Lesser General Public | |
8 | License as published by the Free Software Foundation; either | |
9 | version 2.1 of the License, or (at your option) any later version. | |
10 | ||
11 | The GNU C Library is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Lesser General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public | |
59ba27a6 | 17 | License along with the GNU C Library; if not, see |
5a82c748 | 18 | <https://www.gnu.org/licenses/>. */ |
bb3129bd UD |
19 | |
20 | #include <math.h> | |
21 | ||
1ed0291c | 22 | #include <math_private.h> |
a1132b5e | 23 | #include <libm-alias-double.h> |
e054f494 | 24 | #include <stdint.h> |
bb3129bd UD |
25 | |
26 | static const double zero = 0.0; | |
27 | ||
28 | ||
29 | double | |
30 | __remquo (double x, double y, int *quo) | |
31 | { | |
32 | int64_t hx, hy; | |
33 | uint64_t sx, qs; | |
34 | int cquo; | |
35 | ||
36 | EXTRACT_WORDS64 (hx, x); | |
37 | EXTRACT_WORDS64 (hy, y); | |
38 | sx = hx & UINT64_C(0x8000000000000000); | |
39 | qs = sx ^ (hy & UINT64_C(0x8000000000000000)); | |
40 | hy &= UINT64_C(0x7fffffffffffffff); | |
41 | hx &= UINT64_C(0x7fffffffffffffff); | |
42 | ||
43 | /* Purge off exception values. */ | |
a1ffb40e | 44 | if (__glibc_unlikely (hy == 0)) |
bb3129bd UD |
45 | return (x * y) / (x * y); /* y = 0 */ |
46 | if (__builtin_expect (hx >= UINT64_C(0x7ff0000000000000) /* x not finite */ | |
47 | || hy > UINT64_C(0x7ff0000000000000), 0))/* y is NaN */ | |
48 | return (x * y) / (x * y); | |
49 | ||
50 | if (hy <= UINT64_C(0x7fbfffffffffffff)) | |
51 | x = __ieee754_fmod (x, 8 * y); /* now x < 8y */ | |
52 | ||
a1ffb40e | 53 | if (__glibc_unlikely (hx == hy)) |
bb3129bd UD |
54 | { |
55 | *quo = qs ? -1 : 1; | |
56 | return zero * x; | |
57 | } | |
58 | ||
d9afe48d | 59 | x = fabs (x); |
bb3129bd UD |
60 | INSERT_WORDS64 (y, hy); |
61 | cquo = 0; | |
62 | ||
a820f9b3 | 63 | if (hy <= UINT64_C(0x7fcfffffffffffff) && x >= 4 * y) |
bb3129bd UD |
64 | { |
65 | x -= 4 * y; | |
66 | cquo += 4; | |
67 | } | |
a820f9b3 | 68 | if (hy <= UINT64_C(0x7fdfffffffffffff) && x >= 2 * y) |
bb3129bd UD |
69 | { |
70 | x -= 2 * y; | |
71 | cquo += 2; | |
72 | } | |
73 | ||
74 | if (hy < UINT64_C(0x0020000000000000)) | |
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 | double y_half = 0.5 * 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 | ||
ce8fc784 JM |
104 | /* Ensure correct sign of zero result in round-downward mode. */ |
105 | if (x == 0.0) | |
106 | x = 0.0; | |
bb3129bd UD |
107 | if (sx) |
108 | x = -x; | |
109 | return x; | |
110 | } | |
a1132b5e | 111 | libm_alias_double (__remquo, remquo) |