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inline assembly for cortex m3

Ali Asadzadeh over 14 years ago

Hi
I want to use uc/Probe for LPC1768 and I have difficulty porting this function to cortex.

static CPU_INT32U ProbeDCC_RdCtrl (void)
{ __asm{ mrc P14,0,R0,C0,C0}
}

The compiler generate this error

probe_dcc.c(140): error: #1113: Inline assembler not permitted when generating Thumb code

And when I include #pragma arm and #pragma thumb it will generate this error

probe_dcc.c(137): error: #1114-D: this feature not supported on target architecture/processor

Do you have any idea how to implement the above function?
Regards

0 Anik Samanta over 14 years ago

Hi Ali
Hope by this time you have solved it.

This valid for Cortex M3.
#pragma is not supported by Cortex as it only supports thumb-2 instruction set.
ARM and Thumb instruction set are not valid.

This can be done by a function"__asm int aks(void);"

A demo code is given below:


#include <stm32f10x_lib.h>
#include "stm32_Init.h"

__asm int fn_add(void);          // prototype declaration

int main (void)
{
fn_add();                         // Function call
}

__asm int fn_add(void)            // Function defination
{
 MOV R2,#0x0000ffff;
 MOV R3,#0x0000ffff;
 ADD r0,r2,r3;      The data has to be shifted as r0 is modified after this instruction.
 }