string/FreeBSD/strcspn.c

   1 /*-
   2  * Copyright (c) 2005 David Schultz <das@FreeBSD.ORG>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <sys/cdefs.h>
  28 __FBSDID("$FreeBSD: src/lib/libc/string/strcspn.c,v 1.5 2005/04/02 18:52:44 das Exp $");
  29
  30 #include <sys/types.h>
  31 #include <limits.h>
  32 #include <string.h>
  33
  34 #define IDX(c)  ((u_char)(c) / LONG_BIT)
  35 #define BIT(c)  ((u_long)1 << ((u_char)(c) % LONG_BIT))
  36
  37 size_t
  38 strcspn(const char *s, const char *charset)
  39 {
  40         /*
  41          * NB: idx and bit are temporaries whose use causes gcc 3.4.2 to
  42          * generate better code.  Without them, gcc gets a little confused.
  43          */
  44         const char *s1;
  45         u_long bit;
  46         u_long tbl[(UCHAR_MAX + 1) / LONG_BIT];
  47         int idx;
  48
  49         if(*s == '\0')
  50                 return (0);
  51
  52 #if LONG_BIT == 64      /* always better to unroll on 64-bit architectures */
  53         tbl[0] = 1;
  54         tbl[3] = tbl[2] = tbl[1] = 0;
  55 #else
  56         for (tbl[0] = idx = 1; idx < sizeof(tbl) / sizeof(tbl[0]); idx++)
  57                 tbl[idx] = 0;
  58 #endif
  59         for (; *charset != '\0'; charset++) {
  60                 idx = IDX(*charset);
  61                 bit = BIT(*charset);
  62                 tbl[idx] |= bit;
  63         }
  64
  65         for(s1 = s; ; s1++) {
  66                 idx = IDX(*s1);
  67                 bit = BIT(*s1);
  68                 if ((tbl[idx] & bit) != 0)
  69                         break;
  70         }
  71         return (s1 - s);
  72 }