firmware/libc/atoi.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2002 by Gary Czvitkovicz
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21
  22 #include <stdlib.h>
  23 #include "ctype.h"
  24
  25 int atoi (const char *str)
  26 {
  27     int value = 0;
  28     int sign = 1;
  29
  30     while (isspace(*str))
  31     {
  32         str++;
  33     }
  34
  35     if ('-' == *str)
  36     {
  37         sign = -1;
  38         str++;
  39     }
  40     else if ('+' == *str)
  41     {
  42         str++;
  43     }
  44
  45     while ('0' == *str)
  46     {
  47         str++;
  48     }
  49
  50     while (isdigit(*str))
  51     {
  52         value = (value * 10) + (*str - '0');
  53         str++;
  54     }
  55
  56     return value * sign;
  57 }