1/* Copyright (C) 1991-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <string.h>
19#include <stdint.h>
20#include <libc-pointer-arith.h>
21
22#undef strspn
23#ifndef STRSPN
24# define STRSPN strspn
25#endif
26
27/* Return the length of the maximum initial segment
28 of S which contains only characters in ACCEPT. */
29size_t
30STRSPN (const char *str, const char *accept)
31{
32 if (accept[0] == '\0')
33 return 0;
34 if (__glibc_unlikely (accept[1] == '\0'))
35 {
36 const char *a = str;
37 for (; *str == *accept; str++);
38 return str - a;
39 }
40
41 /* Use multiple small memsets to enable inlining on most targets. */
42 unsigned char table[256];
43 unsigned char *p = memset (table, 0, 64);
44 memset (p + 64, 0, 64);
45 memset (p + 128, 0, 64);
46 memset (p + 192, 0, 64);
47
48 unsigned char *s = (unsigned char*) accept;
49 /* Different from strcspn it does not add the NULL on the table
50 so can avoid check if str[i] is NULL, since table['\0'] will
51 be 0 and thus stopping the loop check. */
52 do
53 p[*s++] = 1;
54 while (*s);
55
56 s = (unsigned char*) str;
57 if (!p[s[0]]) return 0;
58 if (!p[s[1]]) return 1;
59 if (!p[s[2]]) return 2;
60 if (!p[s[3]]) return 3;
61
62 s = (unsigned char *) PTR_ALIGN_DOWN (s, 4);
63
64 unsigned int c0, c1, c2, c3;
65 do {
66 s += 4;
67 c0 = p[s[0]];
68 c1 = p[s[1]];
69 c2 = p[s[2]];
70 c3 = p[s[3]];
71 } while ((c0 & c1 & c2 & c3) != 0);
72
73 size_t count = s - (unsigned char *) str;
74 return (c0 & c1) == 0 ? count + c0 : count + c2 + 2;
75}
76libc_hidden_builtin_def (strspn)
77