HASHTBL.H

//-------------------------------------------------------------------- 
// Microsoft OLE DB Sample Provider  
// (C) Copyright 1994 - 1996 Microsoft Corporation.  All Rights Reserved. 
// 
// @module hashtbl.h | Class Definitions for CHashTbl Class and  
// miscellaneous bookmark functions 
// 
// 
#ifndef _HASHTBL_H_ 
#define _HASHTBL_H_ 
#include "bitarray.h" 
 
#define SIZE_64K   65535// Actually 64*1024-1 
 
 
// This defines the data as stored within the row buffer. 
// Each row has columns laid out sequentially. 
// Use 'offsetof' when doing pointer addition. 
// Note that it is important to align these. 
// Suggest ensuring quadword alignment for double and __int64. 
 
typedef struct _COLUMNDATA { 
SDWORDdwLength;// length of data (not space allocated) 
DWORDdwStatus;// status of column 
BYTEbData[1];// data here and beyond 
} COLUMNDATA, *PCOLUMNDATA; 
 
// This is the layout of a row. 
// Note the unique arrangement of the hash chain pointers  
// inside the row itself. 
// Note also that the structure for columns is defined, and 
// each row contains an array of columns. 
// Bookmarks are named separately from ColumnData, for clarity 
// of usage.  The layout directly matches COLUMNDATA, however. 
// There are asserts which enforce this. 
typedef struct tagRowBuff 
{ 
ULONG       ulRefCount;// reference count of outstanding handles 
ULONG       irowbuffNext;// next row in bookmark hash chain 
USHORT      wBmkHash;// hash value (redundant) 
VOID       *pbBmk;// ptr  to bookmark 
ULONG       cbBmk;// (dwLength) bookmark size, in bytes 
ULONG       dwBmkStatus;// (dwStatus) bookmark status 
ULONG       dwBmk;// (bData)    bookmark value, , maybe row count 
COLUMNDATA  cdData[1];// Column data here and beyond (Bookmark should be here) 
} ROWBUFF, *PROWBUFF; 
 
typedef struct tagSLOT 
{ 
ULONG islotNext; 
ULONG islotPrev; 
ULONG cslot; 
} SLOT, *PSLOT; 
 
typedef struct tagLSTSLOT 
{ 
ULONG       islotFirst; 
ULONG       islotRov; 
ULONG       islotMin; 
ULONG       islotMax; 
BYTE        *rgslot; 
LPBITARRAYpbitsSlot;// bit array to mark active rows 
ULONG       cbExtra; 
ULONG       cbslotLeftOver; 
ULONG       cbSlot; 
ULONG       cbPage; 
ULONG       cbCommitCurrent; 
ULONG       cbCommitMax; 
} LSTSLOT, *PLSTSLOT; 
 
 
HRESULT GetNextSlots(PLSTSLOT plstslot,ULONG cslot, ULONG* pislot); 
VOID DecoupleSlot(PLSTSLOT plstslot, ULONG islot, PSLOT pslot); 
VOID AddSlotToList(PLSTSLOT plstslot, ULONG islot, PSLOT pslot); 
HRESULT ReleaseSlots(PLSTSLOT plstslot,ULONG islot, ULONG cslot); 
HRESULT InitializeSlotList(ULONG cslotMax, ULONG cbSlot, ULONG cbPage, LPBITARRAY pbits, PLSTSLOT* pplstslot, BYTE** prgslot); 
HRESULT ResetSlotList(PLSTSLOT plstslot); 
HRESULT ReleaseSlotList(PLSTSLOT plstslot); 
 
 
#endif