TMS320F280049C: F280049C CLA global variable with initial value

Hi Jiakai,

Const_cla section consists of all the constants. All the other globals are part of bss_cla section. And the initialisation of the bss data should be done within a task only.

Regards,

Veena

Hi Veena,

Thank you for your reply.

I have 3 more questions:

1. Is  the data in .bss_cla section set to zero at the startup automatically, or we need to clear it at main() function?

2. How can I declare a global variable with initial value in .cla file if this variable is only used in CLA side? or how

    can I declare a global variable to .const_cla?

    Since the limitation of CLA compiler, I consider to declare cla global variable in cpu .c file. For example,

    I have a variable definition as below in .cla file:

        int32_t nVal = 1;

    Since this causes CLA compile failure, I try to use a different way to declare nVal as a .const_cla variable as below:

    . In .c file:

       #pragma DATA_SECTION(nVal, ".const_cla")

       int32_t nVal = 1;

    . In .cla file:

       extern int32_t nVal;

    Is there any problem for this implementation?

3. How can I set initial value for a static variable in CLA function?

I hope CLA compiler can improve the way to process the global/static variables with constant values just like CCS

c compiler does for a normal .c file.

Thanks,

Jiakai

1. The bss data contents cannot be guaranteed to be 0. The gel file may do a RAM initialization after you load the program. But it is highly recommended to explicitly initialize all the variables before using it.

2. You can declare it in the .cla file outside the functions to make it global across all CLA tasks. But you cannot initialize the variable outside the task. For this, you can use one task to initialize the variable. You may refer to the Driverlib example cla_ex4_pwm_control which has a global variable initialized as part of a one-time task. the globals defined in .c file is shared between C28x and CLA. And I dont think you can use const_cla section. You may define a custom section name and allocate it in a CLA data memory in the cmd file

3. I think section 2 answers this question

Regards,

Veena

Hi Veena,

I know that example cla_ex4_pwm_control gives us a way to declare a global variable with initial value, but I strongly suggest that CCS CLA compiler supports setting initial values for CLA global variables. These global variables are allocated in .const_cla section, and before assigning the related local shared RAM to CLA, copy all constants to .const_cla section, just like the startup program does for .econst section. In this way, the function can be easily switched between CPU and CLA.

About the 3rd question, I meant the static variable in a CLA function, for example,

void Increase (void)
{
    static int num = 0;
    return num++;
}

thanks,

Jiakai

.cont_cla is section created by the compiler itself, and it is better not to use it with DATA_SECTION pragma.

Unfortunately, the compiler does not support initialization outside the scope of CLA tasks. An alternate solution is to define it in the .c file where initialization is possible. You may allocate that to an LSRAM accessible to CLA.

Initialization of static variables also is not supported in CLA task. That too should ideally happen outside the scope of the function which is not supported.

Regards,

Veena