lib/libc/string/strspn.c

   1 /*      $NetBSD: strspn.c,v 1.18 2012/03/21 00:35:50 christos 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 1.18 2012/03/21 00:35:50 christos Exp $");
  30
  31 #include <assert.h>
  32 #include <inttypes.h>
  33 #include <limits.h>
  34 #include <string.h>
  35
  36 #if ULONG_MAX != 0xffffffffffffffffull
  37
  38 size_t
  39 strspn(const char *s, const char *charset)
  40 {
  41         static const uint8_t idx[8] = { 1, 2, 4, 8, 16, 32, 64, 128 };
  42         uint8_t set[32];
  43         const char *t;
  44 #define UC(a) ((unsigned int)(unsigned char)(a))
  45
  46         _DIAGASSERT(s != NULL);
  47         _DIAGASSERT(charset != NULL);
  48
  49         if (charset[0] == '\0')
  50                 return 0;
  51         if (charset[1] == '\0') {
  52                 for (t = s; *t != '\0'; ++t) {
  53                         if (*t != *charset)
  54                                 break;
  55                 }
  56                 return t - s;
  57         }
  58
  59         (void)memset(set, 0, sizeof(set));
  60
  61         for (; *charset != '\0'; ++charset)
  62                 set[UC(*charset) >> 3] |= idx[UC(*charset) & 7];
  63
  64         for (t = s; *t != '\0'; ++t)
  65                 if ((set[UC(*t) >> 3] & idx[UC(*t) & 7]) == 0)
  66                         break;
  67         return t - s;
  68 }
  69
  70 #else
  71
  72 /* 64 bit system, use four 64 bits registers for bitmask */
  73
  74 static size_t
  75 strspn_x(const char *s_s, const char *charset_s, unsigned long invert)
  76 {
  77         const unsigned char *s = (const unsigned char *)s_s;
  78         const unsigned char *charset = (const unsigned char *)charset_s;
  79         unsigned long m_0, m_4, m_8, m_c;
  80         unsigned char ch, next_ch;
  81         unsigned long bit;
  82         unsigned long check;
  83         size_t count;
  84
  85         /* Four 64bit registers have one bit for each character value */
  86         m_0 = 0;
  87         m_4 = 0;
  88         m_8 = 0;
  89         m_c = 0;
  90
  91         for (ch = *charset; ch != 0; ch = next_ch) {
  92                 next_ch = *++charset;
  93                 bit = 1ul << (ch & 0x3f);
  94                 if (__predict_true(ch < 0x80)) {
  95                         if (ch < 0x40)
  96                                 m_0 |= bit;
  97                         else
  98                                 m_4 |= bit;
  99                 } else {
 100                         if (ch < 0xc0)
 101                                 m_8 |= bit;
 102                         else
 103                                 m_c |= bit;
 104                 }
 105         }
 106
 107         /* For strcspn() we just invert the validity set */
 108         m_0 ^= invert;
 109         m_4 ^= invert;
 110         m_8 ^= invert;
 111         m_c ^= invert;
 112
 113         /*
 114          * We could do remove the lsb from m_0 to terminate at the
 115          * end of the input string.
 116          * However prefetching the next char is benifitial and we must
 117          * not read the byte after the \0 - as it might fault!
 118          * So we take the 'hit' of the compare against 0.
 119          */
 120
 121         ch = *s++;
 122         for (count = 0; ch != 0; ch = next_ch) {
 123                 next_ch = s[count];
 124                 if (__predict_true(ch < 0x80)) {
 125                         check = m_0;
 126                         if (ch >= 0x40)
 127                                 check = m_4;
 128                 } else {
 129                         check = m_8;
 130                         if (ch >= 0xc0)
 131                                 check = m_c;
 132                 }
 133                 if (!((check >> (ch & 0x3f)) & 1))
 134                         break;
 135                 count++;
 136         }
 137         return count;
 138 }
 139
 140 size_t
 141 strspn(const char *s, const char *charset)
 142 {
 143         return strspn_x(s, charset, 0);
 144 }
 145
 146 size_t
 147 strcspn(const char *s, const char *charset)
 148 {
 149         return strspn_x(s, charset, ~0ul);
 150 }
 151 #endif