• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 98 subscribers
  • Views 712 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

Using inline assembly to store LR to C variable

Compiler/AM3358: Reading LR register to a C variable

suraj suraj
Prodigy 110 points

Part Number: AM3358

Tool/software: TI C/C++ Compiler

Hi,

We are trying to read value of LR register into a C variable, for which we used below mentioned inline function, but are getting error #18: expected a ")".

__attribute__( ( always_inline ) ) __STATIC_INLINE VCI_UINT32 __get_LR(void)
{
    register VCI_UINT32 result;

__ASM volatile ("MOV %0, lr\n\t" : "=r" (result));
    return(result);
}

We referred similar query, linked below, but was unable to understand provided solution:

e2e.ti.com/.../280370

 It would be a great help if you could provide us an example code for the same.

  • 0
    TI__Guru**** 252710 points

    The TI ARM compiler does not support GCC-style asm statements.  The best alternative is to implement this function in hand-coded assembly.

    suraj suraj said:
     It would be a great help if you could provide us an example code for the same.

    I'm not aware of an example.  While I did not test it by running it, something close to the following should work ...

    ; UNTESTED EXAMPLE

	.text
	.global	__get_LR
__get_LR:
        MOV       A1, LR
        BX        LR

    Put this code in an assembly language source file that has the file extension .asm.  Add it to your project.

    Thanks and regards,

    -George

  • 0 in reply to George Mock
    Prodigy 110 points

    Thanks George.

    We tried your suggestion but it doesn't satisfy our requirement.

    Our use case is to read value of LR register into some global C variable.

    Could you please help us to achieve this?

    Regards,

    Suraj

  • 0 in reply to suraj suraj
    TI__Guru**** 252710 points

    Unfortunately, I cannot think of a good way to solve your problem with the TI ARM compiler.  If it is practical, consider changing to a GCC ARM compiler, such as the one that comes with Code Composer Studio.

    Thanks and regards,

    -George