/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
   
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.
   
   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.
   
   You should have received a copy of the GNU Library General Public
   License along with this library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
   MA 02111-1307, USA */

/* Calculate a long checksum for a memoryblock. Used to verify pack_isam */

#include <global.h>
#include "my_sys.h"

ulong checksum(const byte *mem, uint count)
{
  ulong crc;
  for (crc=0; count-- ; mem++)
    crc=((crc << 1) + *((uchar*) mem)) +
      test(crc & ((ulong) 1L << (8*sizeof(ulong)-1)));
  return crc;
}