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' &&
  47                     (nptr[1] == 'x' || nptr[1] == 'X')) {
  48                         nptr += 2;
  49                         base = 16;
  50                 } else if (nptr[0] == '0') {
  51                         nptr++;
  52                         base = 8;
  53                 } else {
  54                         base = 10;
  55                 }
  56         } else if (base == 16) {
  57                 if (nptr[0] == '0' &&
  58                     (nptr[1] == 'x' || nptr[1] == 'X')) {
  59                         nptr += 2;
  60                 }
  61         }
  62
  63         while ((d = digitval(*nptr)) >= 0 && d < base) {
  64                 v = v * base + d;
  65                 nptr++;
  66         }
  67
  68         if (endptr)
  69                 *endptr = (char *)nptr;
  70
  71         return minus ? -v : v;
  72 }