1 /* $NetBSD: strspn.c,v 1.3 2023/06/18 22:18:13 rillig Exp $ */
2
3 /*-
4 * Copyright (c) 2008 Joerg Sonnenberger
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #include <sys/cdefs.h>
29 __RCSID("$NetBSD: strspn.c,v 1.3 2023/06/18 22:18:13 rillig Exp $");
30
31 #if !defined(_KERNEL) && !defined(_STANDALONE)
32 #include <assert.h>
33 #include <inttypes.h>
34 #include <limits.h>
35 #include <string.h>
36 #else
37 #include <lib/libkern/libkern.h>
38 #endif
39
40 #if ULONG_MAX != 0xffffffffffffffffull
41
42 size_t
strspn(const char * s,const char * charset)43 strspn(const char *s, const char *charset)
44 {
45 static const uint8_t idx[8] = { 1, 2, 4, 8, 16, 32, 64, 128 };
46 uint8_t set[32];
47 const char *t;
48 #define UC(a) ((unsigned int)(unsigned char)(a))
49
50 if (charset[0] == '\0')
51 return 0;
52 if (charset[1] == '\0') {
53 for (t = s; *t != '\0'; ++t) {
54 if (*t != *charset)
55 break;
56 }
57 return t - s;
58 }
59
60 (void)memset(set, 0, sizeof(set));
61
62 for (; *charset != '\0'; ++charset)
63 set[UC(*charset) >> 3] |= idx[UC(*charset) & 7];
64
65 for (t = s; *t != '\0'; ++t)
66 if ((set[UC(*t) >> 3] & idx[UC(*t) & 7]) == 0)
67 break;
68 return t - s;
69 }
70
71 #else
72
73 /* 64 bit system, use four 64 bits registers for bitmask */
74
75 static size_t
strspn_x(const char * s_s,const char * charset_s,unsigned long invert)76 strspn_x(const char *s_s, const char *charset_s, unsigned long invert)
77 {
78 const unsigned char *s = (const unsigned char *)s_s;
79 const unsigned char *charset = (const unsigned char *)charset_s;
80 unsigned long m_0, m_4, m_8, m_c;
81 unsigned char ch, next_ch;
82 unsigned long bit;
83 unsigned long check;
84 size_t count;
85
86 /* Four 64bit registers have one bit for each character value */
87 m_0 = 0;
88 m_4 = 0;
89 m_8 = 0;
90 m_c = 0;
91
92 for (ch = *charset; ch != 0; ch = next_ch) {
93 next_ch = *++charset;
94 bit = 1ul << (ch & 0x3f);
95 if (__predict_true(ch < 0x80)) {
96 if (ch < 0x40)
97 m_0 |= bit;
98 else
99 m_4 |= bit;
100 } else {
101 if (ch < 0xc0)
102 m_8 |= bit;
103 else
104 m_c |= bit;
105 }
106 }
107
108 /* For strcspn() we just invert the validity set */
109 m_0 ^= invert;
110 m_4 ^= invert;
111 m_8 ^= invert;
112 m_c ^= invert;
113
114 /*
115 * We could do remove the lsb from m_0 to terminate at the
116 * end of the input string.
117 * However prefetching the next char is beneficial and we must
118 * not read the byte after the \0 - as it might fault!
119 * So we take the 'hit' of the compare against 0.
120 */
121
122 ch = *s++;
123 for (count = 0; ch != 0; ch = next_ch) {
124 next_ch = s[count];
125 if (__predict_true(ch < 0x80)) {
126 check = m_0;
127 if (ch >= 0x40)
128 check = m_4;
129 } else {
130 check = m_8;
131 if (ch >= 0xc0)
132 check = m_c;
133 }
134 if (!((check >> (ch & 0x3f)) & 1))
135 break;
136 count++;
137 }
138 return count;
139 }
140
141 size_t
strspn(const char * s,const char * charset)142 strspn(const char *s, const char *charset)
143 {
144 return strspn_x(s, charset, 0);
145 }
146
147 size_t
strcspn(const char * s,const char * charset)148 strcspn(const char *s, const char *charset)
149 {
150 return strspn_x(s, charset, ~0ul);
151 }
152 #endif
153