Kernel Mode Driver Framework >> Pascal (PNP) >> File
WdfDeviceIoDirect(PIO)
參考資訊:
1. Source Code
WdfDeviceIoDirect的概念就是直接Mapping User Buffer,然後Driver使用該Mapped的MDL(Memory Description List)操作,相較於WdfDeviceIoBuffered,因為不須I/O Manager更新回User Buffer,因此,效率會比較好,而如果Driver會操作到DMA(Direct Memory Access)記憶體的話,不適用此方式,雖然司徒目前還沒有寫過DMA相關的Windows Driver,不過依據Microsoft的說明文件來看,使用DMA的話,必須使用另一個API(MmGetMdlVirtualAddress)去取得DMA實體記憶體位址,反之,如果不是DMA的操作,就是PIO(Programmed I/O)方式。
記憶體指標:
Event | Buffer | Length |
---|---|---|
EvtIoRead | Step 1. WdfRequestRetrieveOutputWdmMdl() Step 2. MmGetSystemAddressForMdlSafe() |
傳入的第三個參數 |
EvtIoWrite | Step 1. WdfRequestRetrieveInputWdmMdl() Step 2. MmGetSystemAddressForMdlSafe() |
傳入的第三個參數 |
main.pas
unit main; interface uses DDDK; const DEV_NAME = '\Device\MyDriver'; SYM_NAME = '\DosDevices\MyDriver'; function __DriverEntry(pOurDriver:PDRIVER_OBJECT; pOurRegistry:PUNICODE_STRING):NTSTATUS; stdcall; implementation var szBuffer: array[0..255] of char; procedure IrpFileCreate(Device:WDFDEVICE; Request:WDFREQUEST; FileObject:WDFFILEOBJECT); stdcall; begin DbgPrint('IrpFileCreate', []); WdfRequestComplete(Request, STATUS_SUCCESS); end; procedure IrpFileClose(FileObject:WDFFILEOBJECT); stdcall; begin DbgPrint('IrpFileClose', []); end; procedure IrpRead(Queue:WDFQUEUE; Request:WDFREQUEST; Length:ULONG); stdcall; var mdl: PMDL; len: ULONG; dst: Pointer; begin DbgPrint('IrpRead', []); len:= strlen(@szBuffer) + 1; WdfRequestRetrieveOutputWdmMdl(Request, @mdl); dst:= MmGetSystemAddressForMdlSafe(mdl, LowPagePriority); memcpy(dst, @szBuffer, len); WdfRequestCompleteWithInformation(Request, STATUS_SUCCESS, len); end; procedure IrpWrite(Queue:WDFQUEUE; Request:WDFREQUEST; Length:ULONG); stdcall; var mdl: PMDL; src: Pointer; begin DbgPrint('IrpWrite', []); WdfRequestRetrieveInputWdmMdl(Request, @mdl); src:= MmGetSystemAddressForMdlSafe(mdl, LowPagePriority); memcpy(@szBuffer, src, Length); DbgPrint('Buffer: %s, Length:%d', [szBuffer, Length]); WdfRequestCompleteWithInformation(Request, STATUS_SUCCESS, Length); end; function AddDevice(pOurDriver:WDFDRIVER; pDeviceInit:PWDFDEVICE_INIT):NTSTATUS; stdcall; var device: WDFDEVICE; suDevName: UNICODE_STRING; szSymName: UNICODE_STRING; file_cfg: WDF_FILEOBJECT_CONFIG; ioqueue_cfg: WDF_IO_QUEUE_CONFIG; begin WdfDeviceInitSetIoType(pDeviceInit, WdfDeviceIoDirect); WDF_FILEOBJECT_CONFIG_INIT(@file_cfg, @IrpFileCreate, @IrpFileClose, Nil); WdfDeviceInitSetFileObjectConfig(pDeviceInit, @file_cfg, WDF_NO_OBJECT_ATTRIBUTES); RtlInitUnicodeString(@suDevName, DEV_NAME); RtlInitUnicodeString(@szSymName, SYM_NAME); WdfDeviceInitAssignName(pDeviceInit, @suDevName); WdfDeviceCreate(@pDeviceInit, WDF_NO_OBJECT_ATTRIBUTES, @device); WdfDeviceCreateSymbolicLink(device, @szSymName); WDF_IO_QUEUE_CONFIG_INIT_DEFAULT_QUEUE(@ioqueue_cfg, WdfIoQueueDispatchSequential); ioqueue_cfg.EvtIoRead:= @IrpRead; ioqueue_cfg.EvtIoWrite:= @IrpWrite; Result:= WdfIoQueueCreate(device, @ioqueue_cfg, WDF_NO_OBJECT_ATTRIBUTES, WDF_NO_HANDLE); end; function __DriverEntry(pOurDriver:PDRIVER_OBJECT; pOurRegistry:PUNICODE_STRING):NTSTATUS; stdcall; var config: WDF_DRIVER_CONFIG; begin WDF_DRIVER_CONFIG_INIT(@config, AddDevice); WdfDriverCreate(pOurDriver, pOurRegistry, WDF_NO_OBJECT_ATTRIBUTES, @config, WDF_NO_HANDLE); Result:= STATUS_SUCCESS; end; end.
IrpWrite()複製User Application的資料到szBuffer
IrpRead()回填資料給User Application
app.pas
program main; {$APPTYPE CONSOLE} uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, DIALOGS; var fd: DWORD; ret: DWORD; len: DWORD; szBuf: array[0..255] of char; begin fd:= CreateFile('\\.\MyDriver', GENERIC_READ or GENERIC_WRITE, FILE_SHARE_READ, Nil, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0); if (fd <> INVALID_HANDLE_VALUE) then begin StrCopy(szBuf, 'I am error'); len:= strlen(szBuf)+1; WriteLn(Output, Format('WR: %s, %d', [szBuf, len])); WriteFile(fd, szBuf, len, ret, Nil); ReadFile(fd, szBuf, len, ret, Nil); WriteLn(Output, Format('RD: %s, %d', [szBuf, ret])); CloseHandle(fd); end else begin WriteLn(Output, 'failed to open mydriver'); end; end.
結果