git.zerfleddert.de Git - micropolis/blob - src/tcl/compat/strtoul.c

   1 /*
   2  * strtoul.c --
   3  *
   4  *      Source code for the "strtoul" library procedure.
   5  *
   6  * Copyright 1988 Regents of the University of California
   7  * Permission to use, copy, modify, and distribute this
   8  * software and its documentation for any purpose and without
   9  * fee is hereby granted, provided that the above copyright
  10  * notice appear in all copies.  The University of California
  11  * makes no representations about the suitability of this
  12  * software for any purpose.  It is provided "as is" without
  13  * express or implied warranty.
  14  */
  15
  16 #ifndef lint
  17 static char rcsid[] = "$Header: /sprite/src/lib/tcl/compat/RCS/strtoul.c,v 1.2 91/09/22 14:04:43 ouster Exp $ SPRITE (Berkeley)";
  18 #endif /* not lint */
  19
  20 #include <ctype.h>
  21
  22 /*
  23  * The table below is used to convert from ASCII digits to a
  24  * numerical equivalent.  It maps from '0' through 'z' to integers
  25  * (100 for non-digit characters).
  26  */
  27
  28 static char cvtIn[] = {
  29     0, 1, 2, 3, 4, 5, 6, 7, 8, 9,               /* '0' - '9' */
  30     100, 100, 100, 100, 100, 100, 100,          /* punctuation */
  31     10, 11, 12, 13, 14, 15, 16, 17, 18, 19,     /* 'A' - 'Z' */
  32     20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
  33     30, 31, 32, 33, 34, 35,
  34     100, 100, 100, 100, 100, 100,               /* punctuation */
  35     10, 11, 12, 13, 14, 15, 16, 17, 18, 19,     /* 'a' - 'z' */
  36     20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
  37     30, 31, 32, 33, 34, 35};
  38 \f
  39 /*
  40  *----------------------------------------------------------------------
  41  *
  42  * strtoul --
  43  *
  44  *      Convert an ASCII string into an integer.
  45  *
  46  * Results:
  47  *      The return value is the integer equivalent of string.  If endPtr
  48  *      is non-NULL, then *endPtr is filled in with the character
  49  *      after the last one that was part of the integer.  If string
  50  *      doesn't contain a valid integer value, then zero is returned
  51  *      and *endPtr is set to string.
  52  *
  53  * Side effects:
  54  *      None.
  55  *
  56  *----------------------------------------------------------------------
  57  */
  58
  59 unsigned long int
  60 strtoul(string, endPtr, base)
  61     char *string;               /* String of ASCII digits, possibly
  62                                  * preceded by white space.  For bases
  63                                  * greater than 10, either lower- or
  64                                  * upper-case digits may be used.
  65                                  */
  66     char **endPtr;              /* Where to store address of terminating
  67                                  * character, or NULL. */
  68     int base;                   /* Base for conversion.  Must be less
  69                                  * than 37.  If 0, then the base is chosen
  70                                  * from the leading characters of string:
  71                                  * "0x" means hex, "0" means octal, anything
  72                                  * else means decimal.
  73                                  */
  74 {
  75     register char *p;
  76     register unsigned long int result = 0;
  77     register unsigned digit;
  78     int anyDigits = 0;
  79
  80     /*
  81      * Skip any leading blanks.
  82      */
  83
  84     p = string;
  85     while (isspace(*p)) {
  86         p += 1;
  87     }
  88
  89     /*
  90      * If no base was provided, pick one from the leading characters
  91      * of the string.
  92      */
  93
  94     if (base == 0)
  95     {
  96         if (*p == '0') {
  97             p += 1;
  98             if (*p == 'x') {
  99                 p += 1;
 100                 base = 16;
 101             } else {
 102
 103                 /*
 104                  * Must set anyDigits here, otherwise "0" produces a
 105                  * "no digits" error.
 106                  */
 107
 108                 anyDigits = 1;
 109                 base = 8;
 110             }
 111         }
 112         else base = 10;
 113     } else if (base == 16) {
 114
 115         /*
 116          * Skip a leading "0x" from hex numbers.
 117          */
 118
 119         if ((p[0] == '0') && (p[1] == 'x')) {
 120             p += 2;
 121         }
 122     }
 123
 124     /*
 125      * Sorry this code is so messy, but speed seems important.  Do
 126      * different things for base 8, 10, 16, and other.
 127      */
 128
 129     if (base == 8) {
 130         for ( ; ; p += 1) {
 131             digit = *p - '0';
 132             if (digit > 7) {
 133                 break;
 134             }
 135             result = (result << 3) + digit;
 136             anyDigits = 1;
 137         }
 138     } else if (base == 10) {
 139         for ( ; ; p += 1) {
 140             digit = *p - '0';
 141             if (digit > 9) {
 142                 break;
 143             }
 144             result = (10*result) + digit;
 145             anyDigits = 1;
 146         }
 147     } else if (base == 16) {
 148         for ( ; ; p += 1) {
 149             digit = *p - '0';
 150             if (digit > ('z' - '0')) {
 151                 break;
 152             }
 153             digit = cvtIn[digit];
 154             if (digit > 15) {
 155                 break;
 156             }
 157             result = (result << 4) + digit;
 158             anyDigits = 1;
 159         }
 160     } else {
 161         for ( ; ; p += 1) {
 162             digit = *p - '0';
 163             if (digit > ('z' - '0')) {
 164                 break;
 165             }
 166             digit = cvtIn[digit];
 167             if (digit >= base) {
 168                 break;
 169             }
 170             result = result*base + digit;
 171             anyDigits = 1;
 172         }
 173     }
 174
 175     /*
 176      * See if there were any digits at all.
 177      */
 178
 179     if (!anyDigits) {
 180         p = string;
 181     }
 182
 183     if (endPtr != 0) {
 184         *endPtr = p;
 185     }
 186
 187     return result;
 188 }