Write on REQMASKCLR

Friedrich,

Here is a CCS project to demonstrate the usage of SWI. 8304.SWI.zip

In this code, the main code is executed in USER mode.
A first attempt to write to the REQMASKSET0 register fails, the second time, it is done using a SWI handler.

Our Code Generator Tools offers a way to define a function as a SWI handler using a specific PRAGMA.

#pragma INTERRUPR(ISR_SWI,SWI)

What that means, the function ISR_SWI will not be a regular function, but as SWI exception.

If you look at the swi.h file you will see that aliases are defined to call this ISR_SWI with different parameters.

Let's have a look at the following definition:

#pragma SWI_ALIAS(WRITE_SVC,0)
#pragma SWI_ALIAS(INT_FIQ_ENABLE,1)

void WRITE_SVC(unsigned int address, unsigned int data);
void INT_ENABLE();

main()
{
 WRITE_SVC((unsigned int)(&vimREG->REQMASKSET0,0x00000004);
 INT_ENABLE();
}

The WRITE_SVC function call will be compiled into a swi instruction. (assembly opcode)
This instruction has a 24build in argument field. (bit 0 to bit 23 of the instruction itself) This field will be 0 for the WRITE_SVC.
Same for the INT_ENABLE function call. This will be translated to a swi instruction with the argument field equal to 1.

The SWI handler (ISR_SWI) retrieves from the swi instruction the 24bit field "argument".
Based on the value a swich case will be taken and sub function will be executed.

It is up to you to create additional swi call by updating the swi,h and swi.c file.

Please let me know if I've answer your question.

Best Regards,

Jean-Marc

Friedrich,

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If yes, can you please mark my answer as "Verified Answer" so I can close this thread.

Thanks and Regards,

Jean-Marc