memdump/strtoul.c

   1 /*
   2  * strtoul.c
   3  *
   4  */
   5
   6 #include "mystuff.h"
   7
   8 static inline int isspace(int c)
   9 {
  10     return (c <= ' ');          /* Close enough */
  11 }
  12
  13 static inline int digitval(int ch)
  14 {
  15     if (ch >= '0' && ch <= '9') {
  16         return ch - '0';
  17     } else if (ch >= 'A' && ch <= 'Z') {
  18         return ch - 'A' + 10;
  19     } else if (ch >= 'a' && ch <= 'z') {
  20         return ch - 'a' + 10;
  21     } else {
  22         return -1;
  23     }
  24 }
  25
  26 unsigned long strtoul(const char *nptr, char **endptr, int base)
  27 {
  28     int minus = 0;
  29     unsigned long v = 0;
  30     int d;
  31
  32     while (isspace((unsigned char)*nptr)) {
  33         nptr++;
  34     }
  35
  36     /* Single optional + or - */
  37     {
  38         char c = *nptr;
  39         if (c == '-' || c == '+') {
  40             minus = (c == '-');
  41             nptr++;
  42         }
  43     }
  44
  45     if (base == 0) {
  46         if (nptr[0] == '0' && (nptr[1] == 'x' || nptr[1] == 'X')) {
  47             nptr += 2;
  48             base = 16;
  49         } else if (nptr[0] == '0') {
  50             nptr++;
  51             base = 8;
  52         } else {
  53             base = 10;
  54         }
  55     } else if (base == 16) {
  56         if (nptr[0] == '0' && (nptr[1] == 'x' || nptr[1] == 'X')) {
  57             nptr += 2;
  58         }
  59     }
  60
  61     while ((d = digitval(*nptr)) >= 0 && d < base) {
  62         v = v * base + d;
  63         nptr++;
  64     }
  65
  66     if (endptr)
  67         *endptr = (char *)nptr;
  68
  69     return minus ? -v : v;
  70 }