~drizzle-trunk/drizzle/development

/* Copyright (C) 2000-2001, 2003-2004 MySQL 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; version 2 of the License.

   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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA */

/* Calculate a checksum for a row */

#include "myisam_priv.h"

#include <zlib.h>

using namespace drizzled;

/*

  Calculate a long checksum for a memoryblock.

  SYNOPSIS

    my_checksum()

      crc       start value for crc

      pos       pointer to memory block

      length    length of the block

*/

static ha_checksum my_checksum(ha_checksum crc, const unsigned char *pos, size_t length)

{

  return ha_checksum(crc32((uint32_t)crc, pos, uInt(length)));

}

ha_checksum mi_checksum(MI_INFO *info, const unsigned char *buf)

{

  uint32_t i;

  ha_checksum crc=0;

  MI_COLUMNDEF *rec=info->s->rec;

  for (i=info->s->base.fields ; i-- ; buf+=(rec++)->length)

  {

    const unsigned char *pos;

    ulong length;

    switch (rec->type) {

    case FIELD_BLOB:

    {

      length=_mi_calc_blob_length(rec->length-

					portable_sizeof_char_ptr,

					buf);

      memcpy(&pos, buf+rec->length - portable_sizeof_char_ptr, sizeof(char*));

      break;

    }

    case FIELD_VARCHAR:

    {

      uint32_t pack_length= ha_varchar_packlength(rec->length-1);

      if (pack_length == 1)

        length= (ulong) *(unsigned char*) buf;

      else

        length= uint2korr(buf);

      pos= buf+pack_length;

      break;

    }

    default:

      length=rec->length;

      pos=buf;

      break;

    }

    crc=my_checksum(crc, pos ? pos : (unsigned char*) "", length);

  }

  return crc;

}

ha_checksum mi_static_checksum(MI_INFO *info, const unsigned char *pos)

{

  return my_checksum(0, pos, info->s->base.reclength);

}