The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/libkern/strtoul.c

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    1 /*-
    2  * Copyright (c) 1990, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * This code is derived from software contributed to Berkeley by
    6  * Chris Torek.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 3. Neither the name of the University nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  *
   32  * From: static char sccsid[] = "@(#)strtoul.c  8.1 (Berkeley) 6/4/93";
   33  *
   34  * $FreeBSD: src/sys/libkern/strtoul.c,v 1.3 1999/12/01 22:56:51 archie Exp $
   35  */
   36 
   37 #include <sys/param.h>
   38 #include <sys/systm.h>
   39 #include <sys/ctype.h>
   40 #include <machine/limits.h>
   41 
   42 /*
   43  * Convert a string to an unsigned long integer.
   44  *
   45  * Ignores `locale' stuff.  Assumes that the upper and lower case
   46  * alphabets and digits are each contiguous.
   47  */
   48 unsigned long
   49 strtoul(const char *nptr, char **endptr, int base)
   50 {
   51         const char *s = nptr;
   52         unsigned long acc;
   53         unsigned char c;
   54         unsigned long cutoff;
   55         int neg = 0, any, cutlim;
   56 
   57         /*
   58          * See strtol for comments as to the logic used.
   59          */
   60         do {
   61                 c = *s++;
   62         } while (isspace(c));
   63         if (c == '-') {
   64                 neg = 1;
   65                 c = *s++;
   66         } else if (c == '+')
   67                 c = *s++;
   68         if ((base == 0 || base == 16) &&
   69             c == '' && (*s == 'x' || *s == 'X')) {
   70                 c = s[1];
   71                 s += 2;
   72                 base = 16;
   73         }
   74         if (base == 0)
   75                 base = c == '' ? 8 : 10;
   76         cutoff = (unsigned long)ULONG_MAX / (unsigned long)base;
   77         cutlim = (unsigned long)ULONG_MAX % (unsigned long)base;
   78         for (acc = 0, any = 0;; c = *s++) {
   79                 if (!isascii(c))
   80                         break;
   81                 if (isdigit(c))
   82                         c -= '';
   83                 else if (isalpha(c))
   84                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
   85                 else
   86                         break;
   87                 if (c >= base)
   88                         break;
   89                 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
   90                         any = -1;
   91                 else {
   92                         any = 1;
   93                         acc *= base;
   94                         acc += c;
   95                 }
   96         }
   97         if (any < 0) {
   98                 acc = ULONG_MAX;
   99         } else if (neg)
  100                 acc = -acc;
  101         if (endptr != NULL)
  102                 *((const char **)(void *)endptr) = any ? s - 1 : nptr;
  103         return (acc);
  104 }

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