libc/stdlib/atoll.c

   1 /*
   2  *  ZeX/OS
   3  *  Copyright (C) 2010  Tomas 'ZeXx86' Jedrzejek (zexx86@zexos.org)
   4  *
   5  *  This program is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 long long atoll (const char *s)
  20 {
  21     char **endptr = (char **) &s;
  22     int base = 10;
  23
  24     int nDigit;
  25     long long acc = 0;
  26
  27     while((nDigit = *s) != 0)
  28     {
  29         // Convert to digit
  30         nDigit -= '0';
  31         if(nDigit > 9)
  32             nDigit -= ('A' - '9' - 1);
  33         if(nDigit > base - 1)
  34             break;
  35
  36         // Move the value to the next rank and add the digit
  37         acc *= base;
  38         acc += nDigit;
  39         s ++;
  40     }
  41
  42     if(endptr != 0)
  43         *endptr = (char *) s;
  44
  45     return acc;
  46 }