palmdesktopdatabase.c

CD_高级PALM编程

/********************************************************************
* FILE:				PalmDesktopDatabase.c
*
* DESCRIPTION:		Provides the interfaces necessary to access 
*                   databases created by the PalmDatabaseBuilder.
*
*
* VERSION:		1.0
**********************************************************************/
#include <PalmOS.h>
#include "PalmDesktopDatabase.h"

const int pddbCategoryAppInfoLength = sizeof( AppInfoType );

typedef struct _pddbRecord
{
	UInt32 type;
	// data follows!
} PddbRecordType, *PddbRecordTypePtr;

typedef struct _pddbAppInfo
{
	UInt16	flags;
	UInt16	reserved;
	// data follows!
} PddbAppInfoType, *PddbAppInfoPtr;

static UInt16 PrvPddbAppInfoRecordFlags( DmOpenRef );

/***********************************************************************
 * FUNCTION:    	PddbAppInfoRecord
 *
 * DESCRIPTION: 	This routine replaces the MemHandleLock used when 
 *                  accessing the appInfo block for reading.  This routine
 *                  provides a pointer to the appInfo data and the flags.
 *
 * RETURNED:    	A pointer to the record or NULL. Caller must free this.
 ***********************************************************************/
MemPtr PddbAppInfoRecord
(
	DmOpenRef dbRef,		// (in) database owning this record.
	UInt16 *flagsP			// (in) pointer of location to place type of record
)
{
	LocalID appInfoID;
	MemPtr appInfoDataP;
	MemPtr dataP;
	MemPtr baseP;
	PddbAppInfoPtr appInfoP;
	MemPtr resultP = NULL;
	
	appInfoID = DmGetAppInfoID( dbRef );
	baseP = appInfoDataP = MemLocalIDToLockedPtr(appInfoID, 0);
	if ( appInfoDataP )
	{
		// Skip over category.
		appInfoDataP = (PddbAppInfoPtr)( ( ( char *)appInfoDataP + pddbCategoryAppInfoLength ) );
		appInfoP = (PddbAppInfoPtr)appInfoDataP;
		dataP = (MemPtr)( ( ( char*)appInfoP + sizeof( PddbAppInfoPtr ) ) );
		if ( flagsP )
		{
			*flagsP = appInfoP->flags;
		}
		if ( MemPtrSize( appInfoP ) > sizeof( PddbAppInfoType ) )
		{
			// Create a block for the caller.
			resultP = MemPtrNew( MemPtrSize( appInfoP ) - sizeof( PddbAppInfoType ) );
			MemMove( resultP, dataP, 
				(long)(MemPtrSize( appInfoP ) - sizeof( PddbAppInfoType ) ) );
		}
		MemPtrUnlock( baseP );
	}

	return resultP;	
}

/***********************************************************************
 * FUNCTION:    	PrvPddbAppInfoRecordFlags
 *
 * DESCRIPTION: 	This routine returns the PDDB flags from the app info
 *
 * RETURNED:    	flags.
 ***********************************************************************/
static UInt16 PrvPddbAppInfoRecordFlags
(
	DmOpenRef dbRef		// (in) database owning this record.
)
{
	LocalID appInfoID;
	MemPtr appInfoDataP;
	MemPtr dataP;
	MemPtr baseP;
	PddbAppInfoPtr appInfoP;
	UInt16 flags = 0;
		
			int debug = 	pddbCategoryAppInfoLength;

		
	appInfoID = DmGetAppInfoID(dbRef);
	baseP = appInfoDataP = MemLocalIDToLockedPtr(appInfoID, 0);
	if ( appInfoDataP )
	{
		// Skip over category.
		appInfoDataP = (PddbAppInfoPtr)( ( ( char *)appInfoDataP + pddbCategoryAppInfoLength ) );
		appInfoP = (PddbAppInfoPtr)appInfoDataP;
		dataP = (MemPtr)( ( ( char*)appInfoP + sizeof( PddbAppInfoPtr ) ) );
		flags = appInfoP->flags;
		MemPtrUnlock( baseP );
	}
	return flags;
}


/***********************************************************************
 * FUNCTION:    	PddbRecordLock
 *
 * DESCRIPTION: 	This routine replaces the MemHandleLock used when 
 *                  accessing records for reading.  This routine
 *                  provides a pointer to the data and the type if known.
 *
 * RETURNED:    	A pointer to the record or NULL
 ***********************************************************************/
MemPtr PddbRecordLock
(
	DmOpenRef dbRef,		// (in) database owning this record.
	MemHandle recordH,		// (in) handle to database record to lock.
	UInt32 *typeP			// (in) pointer of location to place type of record
)
{
	MemPtr dataP;
	PddbRecordTypePtr record;
	
	if (typeP) 
	{
		*typeP = 0L;
	}
	
	dataP = MemHandleLock( recordH );
	
	// Obtain the record type if available.
	if ( dataP )
	{
		if ( PrvPddbAppInfoRecordFlags( dbRef ) & pddbDatabaseRecordsHaveType )
		{
			record = (PddbRecordTypePtr)(dataP);
			dataP = (MemPtr)( ( (char *)dataP + sizeof( PddbRecordType ) ) );
			if (typeP) 
			{
				*typeP = record->type;
			}
		}
	}
	return dataP;	
}