mariadb/myisam/mi_checksum.c

/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program 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 General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/* Calculate a checksum for a row */

#include "myisamdef.h"

ha_checksum mi_checksum(MI_INFO *info, const byte *buf)
{
  uint i;
  ha_checksum crc=0;
  MI_COLUMNDEF *rec=info->s->rec;

  for (i=info->s->base.fields ; i-- ; buf+=(rec++)->length)
  {
    const byte *pos;
    const byte *end;
    switch (rec->type) {
    case FIELD_BLOB:
    {
      ulong length=_mi_calc_blob_length(rec->length-
					mi_portable_sizeof_char_ptr,
					buf);
      memcpy((char*) &pos, buf+rec->length- mi_portable_sizeof_char_ptr,
	     sizeof(char*));
      end=pos+length;
      break;
    }
    case FIELD_VARCHAR:
    {
      uint length;
      length=uint2korr(buf);
      pos=buf+2; end=pos+length;
      break;
    }
    default:
      pos=buf; end=buf+rec->length;
      break;
    }
    for ( ; pos != end ; pos++)
      crc=((crc << 8) + *((uchar*) pos)) + (crc >> (8*sizeof(ha_checksum)-8));
  }
  return crc;
}


ha_checksum mi_static_checksum(MI_INFO *info, const byte *pos)
{
  ha_checksum crc;
  const byte *end=pos+info->s->base.reclength;
  for (crc=0; pos != end; pos++)
      crc=((crc << 8) + *((uchar*) pos)) + (crc >> (8*sizeof(ha_checksum)-8));
  return crc;
}