1 | /* Zero byte detection; indexes. Generic C version. |
2 | Copyright (C) 2023-2024 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 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #ifndef _STRING_FZI_H |
20 | #define _STRING_FZI_H 1 |
21 | |
22 | #include <limits.h> |
23 | #include <endian.h> |
24 | #include <string-fza.h> |
25 | |
26 | static __always_inline int |
27 | clz (find_t c) |
28 | { |
29 | if (sizeof (find_t) == sizeof (unsigned long)) |
30 | return __builtin_clzl (c); |
31 | else |
32 | return __builtin_clzll (c); |
33 | } |
34 | |
35 | static __always_inline int |
36 | ctz (find_t c) |
37 | { |
38 | if (sizeof (find_t) == sizeof (unsigned long)) |
39 | return __builtin_ctzl (c); |
40 | else |
41 | return __builtin_ctzll (c); |
42 | } |
43 | |
44 | /* A subroutine for the index_zero functions. Given a test word C, return |
45 | the (memory order) index of the first byte (in memory order) that is |
46 | non-zero. */ |
47 | static __always_inline unsigned int |
48 | index_first (find_t c) |
49 | { |
50 | int r; |
51 | if (__BYTE_ORDER == __LITTLE_ENDIAN) |
52 | r = ctz (c); |
53 | else |
54 | r = clz (c); |
55 | return r / CHAR_BIT; |
56 | } |
57 | |
58 | /* Similarly, but return the (memory order) index of the last byte that is |
59 | non-zero. */ |
60 | static __always_inline unsigned int |
61 | index_last (find_t c) |
62 | { |
63 | int r; |
64 | if (__BYTE_ORDER == __LITTLE_ENDIAN) |
65 | r = clz (c); |
66 | else |
67 | r = ctz (c); |
68 | return sizeof (find_t) - 1 - (r / CHAR_BIT); |
69 | } |
70 | |
71 | #endif /* STRING_FZI_H */ |
72 | |