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Help Putting ARM Instruction Inline GCC

sam d over 12 years ago

Note: This was originally posted on 15th December 2010 at http://forums.arm.com

I am trying to use the "Wait For Interrupt" ARM instruction by typing this in my .c source file:


int  main(void)
{
     __asm__ __volatile__ ( "MCR p15, 0, Rd, c7, c0, 4" );

}

but when I try to compile GCC I get this error:
/tmp/cc5VrFFc.s: Assembler messages:
/tmp/cc5VrFFc.s:153: Error: register expected, not 'Rd,c7,c0,4' -- `mcr p15,0,Rd,c7,c0,4'

and I turned off thumbs using this flag: -mno-thumb

How do I call that instruction?

thanks

I know there is this doc: http://www.ethernut.de/en/documents/arm-inline-asm.html

which I tried using. Didn't help.

The wait for interrupt instruction is here: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0201d/I1035380.html

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sam d over 12 years ago

Note: This was originally posted on 16th December 2010 at http://forums.arm.com

Hi,

Replace 'Rd' with the actual destination register - R0, R1, etc.

HTH.

thanks for your response, but how do I know which register I can use? So it would be something like this??? :

__asm__ __volatile__ ( "MCR p15, 0, R0, c7, c0, 4" );
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sam d over 12 years ago

Note: This was originally posted on 16th December 2010 at http://forums.arm.com

Hi,

Replace 'Rd' with the actual destination register - R0, R1, etc.

HTH.

thanks for your response, but how do I know which register I can use? So it would be something like this??? :

__asm__ __volatile__ ( "MCR p15, 0, R0, c7, c0, 4" );
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