calling assembly routine from C in UV2

did you create a dummy function (code the same in C) and use the generated assembler as a template. The Keil handling of segments etc is complicated enough that any other method is bound to give you headaches.

Actually what I wanted to get done is the return from the asm function should result in the next line of the C code executing.

What are you babbeling about. The opcodes after a RET does NOT get executed.

Erik

did you create a dummy function (code the same in C) and use the generated assembler as a template. The Keil handling of segments etc is complicated enough that any other method is bound to give you headaches.

Actually what I wanted to get done is the return from the asm function should result in the next line of the C code executing.

What are you babbeling about. The opcodes after a RET does NOT get executed.

Erik

He's not babbling, or 'babbeling' for that matter.

If you bothered to look at the code fragment he's posted you'd understand what he means.

Stefan

If you bothered to look at the code fragment he's posted you'd understand what he means

it comes to NOP in disassembly
Of course it does, if the asm code happens to be linked last. There is NO statement as to where it goes in execution.

Erik

Have you considered taking a look at the following example program?

http://www.keil.com/download/docs/c2asm2c.zip.asp

This is a C-ASM-C example project that should get you started.

Jon

Yes, I've looked at the sample. And I tried to do something similar on my own. The problem of control not returning to the next statement after the call to asmtest() function remains.
Here is the full code sample I am using :
------------------------------------------
//test.c
#pragma SMALL

extern void asmtest(void);

void main()
{
char i = 2;

asmtest(); //asm func

i++;
}
----------------------------------------
;asm.a51
NAME asm

?PR?asmtest?asm SEGMENT CODE

PUBLIC asmtest
EXTRN CODE (func)

RSEG ?PR?asmtest?asm
asmtest:
USING 0
LCALL func
RET
END

---------------------------------------
//func.c
void func()
{
}
----------------------------------------

On executing the code above in UV2, the call to asmtest function in assembly works out correct, the call to func() a C module also works, but then the RET from the asm module doesn't give control back to the calling main() function as expected. I get series of NOP in disassembly. Any real suggestions nerds ?

thanks
J

Your program does exactly what you wrote :-)

It calls asmtest() inc i to 3 and the leaves to the OS.
Your problem is: you don't have any OS

what about this:

void main()
{
   char i = 2;

   while (1)
   {
      asmtest(); //asm func
      i++;
   }
}

The i++ is not executed. When control is supposed to return back to that statement, I get NOP.

Meanwhile the c2asm2c sample seems to be in an infinite loop, wherein the main() keeps repeating. after the calls from C to asm & asm to C are over.

J

Hmmm,

It works correctly on my compiler. It even executes the i++.

I'm using the V7.06a tools with the uVision2 debugger.

Jon