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Error found in LPC2xxx port.c files

Posted by Ben on August 18, 2010
I think I have found a possible problem in the following LPC2xxx port.c files

GCC/ARM7_LPC2000/port.c
GCC/ARM7_LPC22xx/port.c
IAR/ARM7_LPC2000/port.c
RVDS/ARM7_LPC21xx/port.c

In all cases the VIC interrupt is enabled before the address of the vector is set. By default the address registers are 0, so if an interrupt is pending the processor will jump to location 0.

Also in some cases the VICIntEnable register is or equalled and in some cases just set. This should not matter, other than the wasted cycles.

from the GCC lpc32xx port.c


VICIntEnable = 0x00000010;



/* The ISR installed depends on whether the preemptive or cooperative

scheduler is being used. */

#if configUSE_PREEMPTION == 1

{

extern void ( vPreemptiveTick )( void );

VICVectAddr4 = ( portLONG ) vPreemptiveTick;

}

#else

{

extern void ( vNonPreemptiveTick )( void );

VICVectAddr4 = ( portLONG ) vNonPreemptiveTick;

}

#endif



VICVectCntl4 = 1;


Really the VIC interrupt should be disabled first, the address then set and finally the interrupt enabled.


regards
Ben

RE: Error found in LPC2xxx port.c files

Posted by Richard on August 18, 2010
Thanks for taking the time to report this potential problem.

Interrupts are disabled in the CPSR within tasks.c, immediately prior to the port layer being called to start the scheduler, after which the code you highlight is executed. Therefore interrupts are disabled when the code you highlight is executed.

Does that satisfy you that the problem does not actually exist - or am I missing something?

Regards.

RE: Error found in LPC2xxx port.c files

Posted by Ben on August 18, 2010
As you say interrupts should be disabled so it shouldn't be a problem.

It just that I am having some problems currently that I haven't got to the bottom of yet. One problems was where I was enabling the VIC interrupt before setting the address, so I did a search of the project tree to make sure there were no other instances and found the port.c file.

I am just being picky, have seen to much code where conditions were incorrectly assumed and get fussy about things.

Regards



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