Windows Driver Model >> Pascal >> File
DO_DIRECT_IO(DMA)
參考資訊:
1. Source Code
2. delphidriverdevelopmentkit
由於我們練習的驅動程式位於上層,本身並沒有觸及過多DMA的細節操作,因此,DO_DIRECT_IO的DMA作法會跟PIO一樣,唯一的區別就是取得DMA位址的方式,必須使用特殊的API取得,這篇練習在於說明有這樣的記憶體差別,當使用者實際觸及DMA驅動程式時,必須詳細閱讀DMA的操作方式,而關於DO_DIRECT_IO(DMA)的流程,可以參考如下圖表說明(IRP_MJ_READ):
記憶體指標:
IRP | Buffer | Length |
---|---|---|
IRP_MJ_READ | (MDL) MmGetMdlVirtualAddress |
(MDL) MmGetMdlByteCount |
IRP_MJ_WRITE | (MDL) MmGetMdlVirtualAddress |
(MDL) MmGetMdlByteCount |
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 pNextDevice: PDEVICE_OBJECT; szBuf: array[0..255] of char; procedure Unload(pOurDriver:PDRIVER_OBJECT); stdcall; begin end; function IrpFile(pOurDevice:PDEVICE_OBJECT; pIrp:PIRP):NTSTATUS; stdcall; var len: ULONG; psk: PIO_STACK_LOCATION; begin len:= 0; psk:= IoGetCurrentIrpStackLocation(pIrp); case psk^.MajorFunction of IRP_MJ_CREATE: DbgPrint('IRP_MJ_CREATE', []); IRP_MJ_READ: begin DbgPrint('IRP_MJ_READ', []); len:= strlen(@szBuf[0])+1; memcpy(MmGetMdlVirtualAddress(pIrp^.MdlAddress), @szBuf[0], len); end; IRP_MJ_WRITE: begin DbgPrint('IRP_MJ_WRITE', []); len:= MmGetMdlByteCount(pIrp^.MdlAddress); memcpy(@szBuf[0], MmGetMdlVirtualAddress(pIrp^.MdlAddress), len); DbgPrint('Buffer: %s, Length: %d', [szBuf, len]); end; IRP_MJ_CLOSE: DbgPrint('IRP_MJ_CLOSE', []); end; Result:= STATUS_SUCCESS; pIrp^.IoStatus.Status:= Result; pIrp^.IoStatus.Information:= len; IoCompleteRequest(pIrp, IO_NO_INCREMENT); end; function IrpPnp(pOurDevice:PDEVICE_OBJECT; pIrp:PIRP):NTSTATUS; stdcall; var psk: PIO_STACK_LOCATION; suSymName: UNICODE_STRING; begin psk:= IoGetCurrentIrpStackLocation(pIrp); if psk^.MinorFunction = IRP_MN_REMOVE_DEVICE then begin RtlInitUnicodeString(@suSymName, SYM_NAME); IoDetachDevice(pNextDevice); IoDeleteDevice(pOurDevice); IoDeleteSymbolicLink(@suSymName); end; IoSkipCurrentIrpStackLocation(pIrp); Result:= IoCallDriver(pNextDevice, pIrp); end; function AddDevice(pOurDriver:PDRIVER_OBJECT; pPhyDevice:PDEVICE_OBJECT):NTSTATUS; stdcall; var suDevName: UNICODE_STRING; suSymName: UNICODE_STRING; pOurDevice: PDEVICE_OBJECT; begin RtlInitUnicodeString(@suDevName, DEV_NAME); RtlInitUnicodeString(@suSymName, SYM_NAME); IoCreateDevice(pOurDriver, 0, @suDevName, FILE_DEVICE_UNKNOWN, 0, FALSE, pOurDevice); pNextDevice:= IoAttachDeviceToDeviceStack(pOurDevice, pPhyDevice); pOurDevice^.Flags:= pOurDevice^.Flags or DO_DIRECT_IO; pOurDevice^.Flags:= pOurDevice^.Flags and not DO_DEVICE_INITIALIZING; Result:= IoCreateSymbolicLink(@suSymName, @suDevName); end; function _DriverEntry(pOurDriver:PDRIVER_OBJECT; pOurRegistry:PUNICODE_STRING):NTSTATUS; stdcall; begin pOurDriver^.MajorFunction[IRP_MJ_PNP]:= @IrpPnp; pOurDriver^.MajorFunction[IRP_MJ_CREATE]:= @IrpFile; pOurDriver^.MajorFunction[IRP_MJ_READ]:= @IrpFile; pOurDriver^.MajorFunction[IRP_MJ_WRITE]:= @IrpFile; pOurDriver^.MajorFunction[IRP_MJ_CLOSE]:= @IrpFile; pOurDriver^.DriverExtension^.AddDevice:=@AddDevice; pOurDriver^.DriverUnload:=@Unload; Result:=STATUS_SUCCESS; end; end.
IrpFile()收到IRP_MJ_WRITE時,Driver複製User Buffer的內容到szBuffer,而收到IRP_MJ_READ時,將szBuffer內容又複製回User Buffer,完成暫存的功能,IoStatus.Information的數值就是ReadFile()或WriteFile()完成的長度。
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