Writing asm code for 32 bit drivers is straightforward. You can embed the code in an __asm { } block.
void DemoFunction()
{
__asm
{
mov eax, 0x01
; more assembly
}
}
But writing assembly in 64 bit driver source code requires a bit more work. The 64 bit compiler will not allow inline assembly. The assembly code will have to be moved to a seperate assembly module (an .asm file).
Step 1 : Write necessary assembly routines in a seperate .asm file
Example : Test.asm
------------------------------------------
.data
; all data variables in your asm code goes here
myData1 dq 0 ; 64 bit data
.code
; all assembly routines go here
TestFunction PROC
; sample function/routine/procedure
; assembly code for the function goes here
ret
TestFunction ENDP
END ; end of assembly file
Step2 : Integrate assembly function with C
In one of your C header files declare the function:
extern void TestFunction(void);
Step 3 : Adding asm file to sources file
In the sources file of your driver you can add the .asm file along with other C files.
Example:
SOURCES = init. c \
ioctl.c \
pnp.c\
power.c\
Test.asm
You can add the same under AMD64_SOURCES or IA64_SOURCES if you required to include the same only in those specific architectures.