1 files changed, 82 insertions, 0 deletions
diff --git a/myisam/mi_rprev.c b/myisam/mi_rprev.c
new file mode 100644
index 00000000000..f8f89235549
--- /dev/null
+++ b/myisam/mi_rprev.c
@@ -0,0 +1,82 @@
+/* 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 */
+
+#include "myisamdef.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, byte *buf, int inx)
+{
+  int error;
+  register uint flag;
+  MYISAM_SHARE *share=info->s;
+  DBUG_ENTER("mi_rprev");
+
+  if ((inx = _mi_check_index(info,inx)) < 0)
+    DBUG_RETURN(my_errno);
+  flag=SEARCH_SMALLER;				/* Read previous */
+  if (info->lastpos == HA_OFFSET_ERROR && info->update & HA_STATE_NEXT_FOUND)
+    flag=0;					/* Read last */
+
+  if (_mi_readinfo(info,F_RDLCK,1))
+    DBUG_RETURN(my_errno);
+  if (share->concurrent_insert)
+    rw_rdlock(&share->key_root_lock[inx]);
+  if (!flag)
+    error=_mi_search_last(info, share->keyinfo+inx,
+			  share->state.key_root[inx]);
+  else if (_mi_test_if_changed(info) == 0)
+    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,
+		     info->lastkey_length, flag, share->state.key_root[inx]);
+
+  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,
+				  flag,
+				  share->state.key_root[inx])))
+	break;
+    }
+  }
+
+  if (share->concurrent_insert)
+    rw_unlock(&share->key_root_lock[inx]);
+  info->update&= (HA_STATE_CHANGED | HA_STATE_ROW_CHANGED);
+  info->update|= HA_STATE_PREV_FOUND;
+  if (error)
+  {
+    if (my_errno == HA_ERR_KEY_NOT_FOUND)
+      my_errno=HA_ERR_END_OF_FILE;
+  }
+  else if (!(*info->read_record)(info,info->lastpos,buf))
+  {
+    info->update|= HA_STATE_AKTIV;		/* Record is read */
+    DBUG_RETURN(0);
+  }
+  DBUG_RETURN(my_errno);
+} /* mi_rprev */