~drizzle-trunk/drizzle/development

/* Copyright (C) 2000-2001, 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

#include "myisam_priv.h"

	/*

	   Read previous row with the same key as previous read

	   One may have done a write, update or delete of the previous row.

	   NOTE! Even if one changes the previous row, the next read is done

	   based on the position of the last used key!

	*/

int mi_rprev(MI_INFO *info, unsigned char *buf, int inx)

{

  int error,changed;

  register uint32_t flag;

  MYISAM_SHARE *share=info->s;

  if ((inx = _mi_check_index(info,inx)) < 0)

    return(errno);

  flag=SEARCH_SMALLER;				/* Read previous */

  if (info->lastpos == HA_OFFSET_ERROR && info->update & HA_STATE_NEXT_FOUND)

    flag=0;					/* Read last */

  if (fast_mi_readinfo(info))

    return(errno);

  changed=_mi_test_if_changed(info);

  if (!flag)

    error=_mi_search_last(info, share->keyinfo+inx,

			  share->state.key_root[inx]);

  else if (!changed)

    error=_mi_search_next(info,share->keyinfo+inx,info->lastkey,

			  info->lastkey_length,flag,

			  share->state.key_root[inx]);

  else

    error=_mi_search(info,share->keyinfo+inx,info->lastkey,

		     USE_WHOLE_KEY, flag, share->state.key_root[inx]);

  if (share->concurrent_insert)

  {

    if (!error)

    {

      while (info->lastpos >= info->state->data_file_length)

      {

	/* Skip rows that are inserted by other threads since we got a lock */

	if  ((error=_mi_search_next(info,share->keyinfo+inx,info->lastkey,

				    info->lastkey_length,

				    SEARCH_SMALLER,

				    share->state.key_root[inx])))

	  break;

      }

    }

  }

  info->update&= (HA_STATE_CHANGED | HA_STATE_ROW_CHANGED);

  info->update|= HA_STATE_PREV_FOUND;

  if (error)

  {

    if (errno == HA_ERR_KEY_NOT_FOUND)

      errno=HA_ERR_END_OF_FILE;

  }

  else if (!buf)

  {

    return(info->lastpos==HA_OFFSET_ERROR ? errno : 0);

  }

  else if (!(*info->read_record)(info,info->lastpos,buf))

  {

    info->update|= HA_STATE_AKTIV;		/* Record is read */

    return(0);

  }

  return(errno);

} /* mi_rprev */