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TMS320F28069: occupy larger space if running in CLA than running in C28X RAM for the same function

Howard Zou
Genius 12365 points
Part Number: TMS320F28069

Hi,

my customer has configured a function to be loaded in flash, but can be run in C28X RAM or CLA.

If configured to be run in C28X RAM, the memory map will show that the function occupy 31(hex) space. There is only OffGridBusHighChk1 function in INT_ISR_Test_OffPro.c so we consider the space for the obj to be the same for OffGridBusHighChk1 function.

If configured to be run in CLA, the same function OffGridBusHighChk1 will occupy f4(hex) space.

Why is there such a difference?

Is it real that we will take f4(hex) space in CLA Program RAM when running this function in CLA?

  • 0
    TI__Guru* 90975 points

    Howard,

    Is optimization enabled for both the C28x and the CLA code?

    Differences in code size and performance will depend on what the code is doing.  The CLA has a different instruction set and different addressing modes than the C28x.  Depending on what the code is doing, this could account for the difference. 

    A couple of examples:

    • All CLA instructions occupy 32-bits.  The c28x has a mix of 16bit and 32bit instructions. 
    • The branches on the CLA are different in 3 instructions after the branch instruction are always executed. With optimization on, the compiler will try to fill these spaces with actual instructions it will.  If that is not possible, then NOPs are added to fill the space. 

    There is a comparison between the C28x and the CLA in the CLA SW Development Guide: 

    Regards

    Lori

  • 0 in reply to Lori Heustess
    TI__Genius 12365 points

    Lori,

    thank you.

    I have a quick question, since what we see in memory map is the space occupied in flash, is it the same space really needed when running the function in CLA RAM(0xf4) or C28X RAM(0x31)?

  • 0 in reply to Howard Zou
    TI__Guru* 90975 points

    Yes, it will be the same size.  

  • 0 in reply to Lori Heustess
    TI__Genius 12365 points

    Lori,

    thank you.

    Is optimization enabled for both the C28x and the CLA code?

    I can only find optimization by right click on project- properties- build- C2000 compiler- Optimization Tab- Optimization level.

    I guess if we enable it, it will optimize the code for both C28x and CLA, right?

    And can we conclude that CLA space is always >= C28x space required for same code?

  • 0 in reply to Howard Zou
    TI__Guru* 90975 points

    Howard Zou said:
    I can only find optimization by right click on project- properties- build- C2000 compiler- Optimization Tab- Optimization level.

    In general, the project optimizations will apply to all of the c code whether it is C28x or CLA. 

    A user can, however, apply specific optimizations to a file by right clicking on the file, selecting properties, and changing the optimization for that specific file. If a user hasn't done this, then the project optimizations will apply. 

    Howard Zou said:
    And can we conclude that CLA space is always >= C28x space required for same code?

    This is likely true.  As I mentioned the delta will depend on what the code is doing. 

    Best Regards

    Lori