Assembler error: Illegal mnemonic specified

Imran Khan68504

Intellectual 550 points

Hi guys,

I'm trying to write some basic functions to handle the process stack pointer (PSP) and main stack pointer (MSP).

For example,

uint32_t __get_PSP(void)
{
__asm("mrs r0, psp");
__asm("bx lr");
}

then in main I call this function by saying:

uint32_t x = __get_PSP();

The assembler gives me errors, saying the asm lines are using illegal mnemonics, but if I execute the instruction ("mrs r0, psp") in the *main* function I don't get any error. Why is that?

over 14 years ago

0 Imran Khan68504 over 14 years ago

Intellectual 550 points

adding a tab before mrs and bx does the trick:

__asm(" mrs r0, psp");
__asm(" bx lr");

0 George Mock over 14 years ago in reply to Imran Khan68504

TI__Guru**** 251180 points

Functions that are entirely asm statements tend to have problems. The compiler may still generate the code to setup/tear down a local frame. Or, your asm() statements may incorrectly presume a frame is or is not present. This related thread, while for C2000, applies to ARM as well. Support for the GCC attribute naked will be implemented, but the schedule is not known at this time.

Thanks and regards,

-George

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Assembler error: Illegal mnemonic specified