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Problem in converting the ARM code into THUMB

Desaraju Ravi Kumar

Hi,
Good Day.

I am working on ARM7TDMI core processor from Analog Devices family (ADuC703x). I developed a preemptive scheduler on the same in ARM environment. The functionality of the same is fine and its working well. For the purpose of optimization, i migrated into thumb mode using Keil RV compiler option (by changing the code generation option to THUMB mode and the optimization level option to 3 in C/C++ tab of the target settings option).

After changing the settings my code size is reduced by 2 KB. But, the complete functionality of the software got changed.

Can anybody help me out to get out of this problem?
Also, I would like to know why this kind of behavior is occurring... Please let me know your valuable suggesions.

Thanking you in anticipation,
Ravi Kumar Desaraju.

Parents
  • 0 in reply to Catcus Blip

    Hmm... I'm afraid the system in question cannot qualify as 'safety critical': it appears some basic problems have not been sorted out yet.
    I agree with Tamir, why not look around for a 'tried and true' third-party RTOS? After all, you are not trying to develop your own compiler, shouldn't the same apply to an RTOS?

Reply
  • 0 in reply to Catcus Blip

    Hmm... I'm afraid the system in question cannot qualify as 'safety critical': it appears some basic problems have not been sorted out yet.
    I agree with Tamir, why not look around for a 'tried and true' third-party RTOS? After all, you are not trying to develop your own compiler, shouldn't the same apply to an RTOS?

Children
  • 0 in reply to Mike Kleshov

    Hi Mike and Tamir,

    I do agree with you ppl about using the IRQ handler instead of FIQ. As I explained earlier, my system is a safety critical thats the only point which forced me to work with FIQ. Moreover, my scheduler is working fine with all the timing considerations in ARM mode. I am facing the problem with THUMB mode only.

    The reason why we did not prefer to go with already available RTOS is memory consideration... This particular chip is having 30KB of FLASH and 4 KB of SRAM. So.. we are developing our own scheduler with minimum functionality (viz., we don't have resource sharing concept in this project, so no need to develop mutex and seam phore etc... In a broad way we are implementing the RM algorithm in our scheduler).

    In ARM mode the size of my code is 3 KB. When I convert and build the code in THUMB mode, I observed that the scheduler code is occupying just 1.8KB. So, I thought its better to go for THUMB mode to reduce the code size further (worst case, it would become 2 KB. which saves 1 KB of FLASH memory....).

    Tamir,

    I referred the link which you have provided. Its really useful... thanks a lot.