DBDeref()

void *	DBDeref(
        optr		*ref);

This routine is passed an optr to a locked DB item. The routine returns the address of the item.

Warnings: The optr becomes invalid when the DB item is unlocked.

Include: dbase.h

DBDirty()

void	DBUnlock(
        const void *		ptr);

This routine marks a DB item as dirty; this insures that the VM manager will copy its item-block back to the disk before freeing its memory. The routine is passed a pointer to anywhere within the item.

Tips and Tricks: All the items in an item block are marked dirty at once; thus, you can call this routine just once for several items in the same item block. Only the segment portion of the pointer is significant; thus, you can pass a pointer to anywhere in the item. This is useful if you have incremented the pointer to the item.

Include: dbase.h

DBFree()

void	DBFree(
        VMFileHandle		file,
        DBGroup		group,
        DBItem		item);

This routine frees the specified item. It does not invalidate pointers to other items in the group. It is passed the file, group, and item handles specifying the item; it does not return anything.

Never Use Situations:
Never call DBFree() on a locked item. If you do, the item-block's lock count will not be decremented, which will prevent the item block from ever being properly unlocked.

Include: dbase.h

See Also: DBFreeUngrouped().

DBFreeUngrouped()

void	DBFreeUngrouped(
        VMFileHandle		file,
        DBGroupAndItem		id);

This routine frees the specified item. It does not invalidate pointers to other ungrouped items. It is passed the file handle and DBGroupAndItem value specifying the item; it does not return anything.

Never Use Situations: Never call DBFreeUngrouped() on a locked item. If you do, the item-block's lock count will not be decremented, which will prevent the item block from ever being properly unlocked.

Include: dbase.h

See Also: DBFree().

DBGetMap()

DBGroupAndItem 	DBGetmap(
        VMFileHandle		file);

This routine returns the DBGroupAndItem structure for the passed file's map item. If there is no map item, it returns a null handle.

Include: dbase.h

See Also: DBSetMap(),DBLockMap().

DBGroupAlloc()

DBGroup	DBGroupAlloc(
        VMFileHandle		file);

This routine allocates a new DB group in the specified file and returns its handle. If the group cannot be allocated, DBGroupAlloc() returns a null handle.

Include: dbase.h

DBGroupFree()

void	DBGroupFree(
        VMFileHandle		file,
        DBGroup		group);

This routine frees the specified group. This deletes all items and item-blocks associated with the group. It is passed the file and group handle specifying the group. Note that you can free a group even if some of its items are locked; those locked items will also be freed.

Include: dbase.h

DBGroupFromGroupAndItem()

DBGroup	DBGroupFromGroupAndItem(
        DBGroupAndItem		id);

This macro returns the DBGroup portion of a DBGroupAndItem value.

Include: dbase.h

DBInsertAt()

void	DBInsertAt(
        VMFileHandle		file,			
        DBGroup		group,
        DBItem		item,
        word		insertOffset,
        word		insertCount);

This routine inserts bytes at a specified offset within a DB item. The bytes are zero-initialized. It is passed the file, group, and item handles specifying a DB item, as well as an offset within the cell and a number of bytes to insert. It inserts the specified number of bytes beginning at the specified offset; the data which was at the passed offset will end up immediately after the inserted bytes.

Warnings: This routine invalidates pointers to other items in the same group.

Include: dbase.h

DBInsertAtUngrouped()

void	DBInsertAtUngrouped(
        VMFileHandle		file,			
        DBGroupAndItem		id,
        word		insertOffset,
        word		insertCount);

This routine is just like DBInsertAt(), except it is passed a DBGroupAndItem value instead of separate group and item handles.

Warnings: This routine invalidates pointers to other ungrouped items.

Include: dbase.h

DBItemFromGroupAndItem()

DBItem	DBItemFromGroupAndItem(
        DBGroupAndItem		id);

This macro returns the DBItem portion of a DBGroupAndItem value.

Include: dbase.h