參考資訊：
https://wasm.in/
http://four-f.narod.ru/
https://github.com/steward-fu/ddk
由於I/O Timer的Timer間隔固定為一秒，如果想要可以彈性設定的Timer間隔，需要使用DPC Timer，使用的步驟如下：
1. KeInitializeTimer() 2. KeInitializeDpc() 3. KeSetTimer() 4. KeCancelTimer()
DPC Timer如果使用KeSetTimer()做設定時，其Timer為一次性，也就是Callback僅會被呼叫一次，如果要使用週期性Timer，則需要改用KeSetTimerEx()，KeSetTimerEx()宣告如下：
BOOLEAN KeSetTimerEx(PKTIMER Timer, LARGE_INTEGER DueTime, LONG Period, PKDPC Dpc);
DueTime是第一次Timer的間隔，之後的間隔則使用Period數值
main.asm
.386p
.model flat, stdcall
option casemap:none
include c:\masm32\include\w2k\ntstatus.inc
include c:\masm32\include\w2k\ntddk.inc
include c:\masm32\include\w2k\ntoskrnl.inc
include c:\masm32\include\w2k\ntddkbd.inc
include c:\masm32\Macros\Strings.mac
includelib c:\masm32\lib\wxp\i386\ntoskrnl.lib
public DriverEntry
MyDeviceExtension struct
cnt DWORD ?
dpc KDPC <>
obj KTIMER <>
pNextDev PDEVICE_OBJECT ?
MyDeviceExtension ends
IOCTL_START equ CTL_CODE(FILE_DEVICE_UNKNOWN, 800h, METHOD_BUFFERED, FILE_ANY_ACCESS)
IOCTL_STOP equ CTL_CODE(FILE_DEVICE_UNKNOWN, 801h, METHOD_BUFFERED, FILE_ANY_ACCESS)
.const
MSG_START byte "IOCTL_START",0
MSG_STOP byte "IOCTL_STOP",0
.code
OnTimer proc uses esi pDpc : PKDPC, pContext : PVOID, pArg1 : PVOID, PArg2 : PVOID
mov eax, pContext
mov esi, (DEVICE_OBJECT ptr [eax]).DeviceExtension
inc (MyDeviceExtension ptr[esi]).cnt
invoke DbgPrint, $CTA0("DpcTimer: %d\n"), (MyDeviceExtension ptr[esi]).cnt
ret
OnTimer endp
IrpOpenClose proc pMyDevice : PDEVICE_OBJECT, pIrp : PIRP
IoGetCurrentIrpStackLocation pIrp
movzx eax, (IO_STACK_LOCATION ptr [eax]).MajorFunction
.if eax == IRP_MJ_CREATE
invoke DbgPrint, $CTA0("IRP_MJ_CREATE")
.elseif eax == IRP_MJ_CLOSE
invoke DbgPrint, $CTA0("IRP_MJ_CLOSE")
.endif
mov eax, pIrp
and (_IRP ptr [eax]).IoStatus.Information, 0
mov (_IRP ptr [eax]).IoStatus.Status, STATUS_SUCCESS
fastcall IofCompleteRequest, pIrp, IO_NO_INCREMENT
mov eax, STATUS_SUCCESS
ret
IrpOpenClose endp
IrpIOCTL proc uses esi pMyDevice : PDEVICE_OBJECT, pIrp : PIRP
local hThread : DWORD
local pThread : PVOID
local cnt : LARGE_INTEGER
mov eax, pMyDevice
mov esi, (DEVICE_OBJECT ptr [eax]).DeviceExtension
IoGetCurrentIrpStackLocation pIrp
mov eax, (IO_STACK_LOCATION ptr [eax]).Parameters.DeviceIoControl.IoControlCode
.if eax == IOCTL_START
invoke DbgPrint, offset MSG_START
or cnt.HighPart, -1
mov cnt.LowPart, -10000000
and (MyDeviceExtension ptr[esi]).cnt, 0
invoke KeSetTimerEx, addr (MyDeviceExtension ptr[esi]).obj, cnt.LowPart, cnt.HighPart, 1000, addr (MyDeviceExtension ptr[esi]).dpc
.elseif eax == IOCTL_STOP
invoke DbgPrint, offset MSG_STOP
invoke KeCancelTimer, addr (MyDeviceExtension ptr[esi]).obj
.endif
mov eax, pIrp
mov (_IRP ptr [eax]).IoStatus.Status, STATUS_SUCCESS
and (_IRP ptr [eax]).IoStatus.Information, 0
fastcall IofCompleteRequest, pIrp, IO_NO_INCREMENT
mov eax, STATUS_SUCCESS
ret
IrpIOCTL endp
Unload proc pMyDriver : PDRIVER_OBJECT
local szSymName : UNICODE_STRING
invoke RtlInitUnicodeString, addr szSymName, $CTW0("\\DosDevices\\MyDriver")
invoke IoDeleteSymbolicLink, addr szSymName
mov eax, pMyDriver
invoke IoDeleteDevice, (DRIVER_OBJECT ptr [eax]).DeviceObject
ret
Unload endp
DriverEntry proc pMyDriver : PDRIVER_OBJECT, pMyRegistry : PUNICODE_STRING
local pMyDevice : PDEVICE_OBJECT
local szDevName : UNICODE_STRING
local szSymName : UNICODE_STRING
mov eax, pMyDriver
mov (DRIVER_OBJECT ptr [eax]).MajorFunction[IRP_MJ_CREATE * (sizeof PVOID)], offset IrpOpenClose
mov (DRIVER_OBJECT ptr [eax]).MajorFunction[IRP_MJ_CLOSE * (sizeof PVOID)], offset IrpOpenClose
mov (DRIVER_OBJECT ptr [eax]).MajorFunction[IRP_MJ_DEVICE_CONTROL * (sizeof PVOID)], offset IrpIOCTL
mov (DRIVER_OBJECT ptr [eax]).DriverUnload, offset Unload
invoke RtlInitUnicodeString, addr szDevName, $CTW0("\\Device\\MyDriver")
invoke RtlInitUnicodeString, addr szSymName, $CTW0("\\DosDevices\\MyDriver")
invoke IoCreateDevice, pMyDriver, sizeof MyDeviceExtension, addr szDevName, FILE_DEVICE_UNKNOWN, 0, FALSE, addr pMyDevice
.if eax == STATUS_SUCCESS
mov eax, pMyDevice
or (DEVICE_OBJECT ptr [eax]).Flags, DO_BUFFERED_IO
and (DEVICE_OBJECT ptr [eax]).Flags, not DO_DEVICE_INITIALIZING
mov eax, pMyDevice
mov eax, (DEVICE_OBJECT ptr [eax]).DeviceExtension
invoke KeInitializeTimer, addr (MyDeviceExtension ptr [eax]).obj
mov eax, pMyDevice
mov eax, (DEVICE_OBJECT ptr [eax]).DeviceExtension
invoke KeInitializeDpc, addr (MyDeviceExtension ptr [eax]).dpc, offset OnTimer, pMyDevice
invoke IoCreateSymbolicLink, addr szSymName, addr szDevName
.endif
ret
DriverEntry endp
end DriverEntry
.end
app.asm
.386p
.model flat, stdcall
option casemap:none
include c:\masm32\include\windows.inc
include c:\masm32\include\masm32.inc
include c:\masm32\include\user32.inc
include c:\masm32\include\msvcrt.inc
include c:\masm32\include\kernel32.inc
include c:\masm32\include\w2k\ntddkbd.inc
include c:\masm32\Macros\Strings.mac
includelib c:\masm32\lib\user32.lib
includelib c:\masm32\lib\masm32.lib
includelib c:\masm32\lib\msvcrt.lib
includelib c:\masm32\lib\kernel32.lib
IOCTL_START equ CTL_CODE(FILE_DEVICE_UNKNOWN, 800h, METHOD_BUFFERED, FILE_ANY_ACCESS)
IOCTL_STOP equ CTL_CODE(FILE_DEVICE_UNKNOWN, 801h, METHOD_BUFFERED, FILE_ANY_ACCESS)
.const
DEV_NAME db "\\.\MyDriver",0
.data?
hFile dd ?
dwRet dd ?
.code
start:
invoke CreateFile, offset DEV_NAME, GENERIC_READ or GENERIC_WRITE, FILE_SHARE_READ, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0
mov hFile, eax
invoke DeviceIoControl, hFile, IOCTL_START, NULL, 0, NULL, 0, offset dwRet, NULL
invoke Sleep, 3000
invoke DeviceIoControl, hFile, IOCTL_STOP, NULL, 0, NULL, 0, offset dwRet, NULL
invoke CloseHandle, hFile
invoke ExitProcess, 0
end start
完成