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Commit | Line | Data |
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bc9f6000 | 1 | /* Compute remainder and a congruent to the quotient. |
dff8da6b | 2 | Copyright (C) 1997-2024 Free Software Foundation, Inc. |
bc9f6000 | 3 | This file is part of the GNU C Library. |
bc9f6000 UD |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or | |
41bdb6e2 AJ |
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. | |
bc9f6000 UD |
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 | |
41bdb6e2 | 13 | Lesser General Public License for more details. |
bc9f6000 | 14 | |
41bdb6e2 | 15 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 16 | License along with the GNU C Library; if not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
bc9f6000 UD |
18 | |
19 | #include <math.h> | |
20 | ||
1ed0291c | 21 | #include <math_private.h> |
a1132b5e | 22 | #include <libm-alias-double.h> |
9e97f239 | 23 | #include <stdint.h> |
bc9f6000 UD |
24 | |
25 | static const double zero = 0.0; | |
26 | ||
27 | ||
28 | double | |
29 | __remquo (double x, double y, int *quo) | |
30 | { | |
9e97f239 WD |
31 | int64_t hx, hy; |
32 | uint64_t sx, qs; | |
33 | int cquo; | |
bc9f6000 | 34 | |
9e97f239 WD |
35 | EXTRACT_WORDS64 (hx, x); |
36 | EXTRACT_WORDS64 (hy, y); | |
37 | sx = hx & UINT64_C(0x8000000000000000); | |
38 | qs = sx ^ (hy & UINT64_C(0x8000000000000000)); | |
39 | hy &= UINT64_C(0x7fffffffffffffff); | |
40 | hx &= UINT64_C(0x7fffffffffffffff); | |
bc9f6000 UD |
41 | |
42 | /* Purge off exception values. */ | |
9e97f239 WD |
43 | if (__glibc_unlikely (hy == 0)) |
44 | return (x * y) / (x * y); /* y = 0 */ | |
45 | if (__builtin_expect (hx >= UINT64_C(0x7ff0000000000000) /* x not finite */ | |
46 | || hy > UINT64_C(0x7ff0000000000000), 0))/* y is NaN */ | |
34b402e5 | 47 | return (x * y) / (x * y); |
bc9f6000 | 48 | |
9e97f239 WD |
49 | if (hy <= UINT64_C(0x7fbfffffffffffff)) |
50 | x = __ieee754_fmod (x, 8 * y); /* now x < 8y */ | |
bc9f6000 | 51 | |
9e97f239 | 52 | if (__glibc_unlikely (hx == hy)) |
bc9f6000 UD |
53 | { |
54 | *quo = qs ? -1 : 1; | |
55 | return zero * x; | |
56 | } | |
57 | ||
c5d5d574 | 58 | x = fabs (x); |
9e97f239 | 59 | INSERT_WORDS64 (y, hy); |
bc9f6000 UD |
60 | cquo = 0; |
61 | ||
9e97f239 | 62 | if (hy <= UINT64_C(0x7fcfffffffffffff) && x >= 4 * y) |
bc9f6000 | 63 | { |
34b402e5 | 64 | x -= 4 * y; |
63551311 UD |
65 | cquo += 4; |
66 | } | |
9e97f239 | 67 | if (hy <= UINT64_C(0x7fdfffffffffffff) && x >= 2 * y) |
63551311 UD |
68 | { |
69 | x -= 2 * y; | |
bc9f6000 UD |
70 | cquo += 2; |
71 | } | |
bc9f6000 | 72 | |
9e97f239 | 73 | if (hy < UINT64_C(0x0020000000000000)) |
bc9f6000 | 74 | { |
34b402e5 | 75 | if (x + x > y) |
bc9f6000 | 76 | { |
34b402e5 | 77 | x -= y; |
d705269e | 78 | ++cquo; |
34b402e5 | 79 | if (x + x >= y) |
63551311 UD |
80 | { |
81 | x -= y; | |
82 | ++cquo; | |
83 | } | |
bc9f6000 UD |
84 | } |
85 | } | |
86 | else | |
87 | { | |
34b402e5 | 88 | double y_half = 0.5 * y; |
63551311 | 89 | if (x > y_half) |
bc9f6000 | 90 | { |
34b402e5 | 91 | x -= y; |
d705269e | 92 | ++cquo; |
34b402e5 | 93 | if (x >= y_half) |
63551311 UD |
94 | { |
95 | x -= y; | |
96 | ++cquo; | |
97 | } | |
bc9f6000 UD |
98 | } |
99 | } | |
100 | ||
101 | *quo = qs ? -cquo : cquo; | |
102 | ||
ce8fc784 JM |
103 | /* Ensure correct sign of zero result in round-downward mode. */ |
104 | if (x == 0.0) | |
105 | x = 0.0; | |
63551311 UD |
106 | if (sx) |
107 | x = -x; | |
bc9f6000 UD |
108 | return x; |
109 | } | |
a1132b5e | 110 | libm_alias_double (__remquo, remquo) |