#include <stdio.h>

/************************************************************************/
/* checksum -- verify checksum						*/
/************************************************************************/

int checksum (buff, bufflen)
char *buff ;
int bufflen ;
{
   int ctr ;
   int retval ;
   char tmpstr [5] ;
   long strtol () ;
   unsigned int chk_sum = (unsigned) 0 ;
   int twos_comp ;

   ctr = 0 ;
   while (ctr < (bufflen - 5))
   {
      chk_sum = chk_sum + (buff [ctr] & 0x7f) ;
      ctr ++ ;
   }
   strncpy (tmpstr, &buff [bufflen - 5], 4) ;
   tmpstr [4] = '\0' ;
   twos_comp = (int) strtol (tmpstr, (char **) NULL, 16) ;
   retval = (((chk_sum + twos_comp) & 0xFFFF) == 0) ? 0 : 1 ;
   return (retval) ;
}