LAUNCHXL-F280039C: How to read RPC to the C variable right in C-source file, avoiding creating a separate .asm file.

Hello Kostiantyn,

In assembly the way to read the RPC register is by pushing it to the stack and popping it into a register. I am not aware of a way to do this in using only C; you could try to find the address of the RPC register in memory, but I don't believe there is access to this in C code.

Best regards,

Omer Amir

Perhaps I didn't phrase my question very clearly :)
It goes without saying that the capabilities of the C language are insufficient, it needs to use assembler commands :)
But, I would like to clarify whether this can be done without creating a separate .asm file, that is, by placing these asm-commands directly in the C code using _asm("..."), in C- function, or, maybe in C-inline function.

Thanks!

Hello Kostiantyn,

You should be able to use the push/pop method using _asm(), I don't see a problem with doing this. I have used the assembly inline function before, it works fine. I recommend trying this on your device to check.

Best regards,

Omer Amir

Here 
https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/693819/ccs-tms320f280049-how-to-read-rpc 
I saw an example of how this can be wrapped in an asm function. But my knowledge in assembler is still very weak, therefore, could you please suggest how to modify this to save directly in C variable? And I suppose in this case the ".global _getRPC" and "LRETR" commands will not be needed.

; assembly stub to get RPC

.global _getRPC

_getRPC:
PUSH   RPC
POP     ACC
LRETR

Thanks.

I also tried like this:
1) Defined global variable:

volatile unsigned int VAR;

2) Inside C-function, I put this code:

_asm(" .global VAR");
_asm(" PUSH RPC");
_asm(" POP ACC");
_asm(" MOVL @VAR,ACC");

But, the variable VAR is kept unchanged. There is probably something wrong here.

Thanks a lot!:))
Btw, it is possible to avoid the warning by modifying the return like this:
 

uint32_t getRPC(void)
{
    __asm(" PUSH RPC");
    __asm(" POP ACC");
    __asm(" LRETR");
    return 0;
}

Yes, that works.