TMS320F280049: How to place _c_int00 on a flash location?

Wayne Huang

Part Number: TMS320F280049

Dear Champs,

I am asking this for our customer.

The user wants to place the address value of _c_int00 (say, 0x00082836 in the .map) generated by the compiler on a flash location (.out is EABI format).

The user finds that the compiler has a error for the below statement because _c_int00 is not a constant to the compiler.

extern uint32_t _c_int00;
#pragma DATA_SECTION(testVar, "testEntryPoint")
#pragma RETAIN(testVar)
volatile const uint32_t testVar = (_c_int00);

Do you have any suggestion how the user can place the address value of _c_int00 on a flash location?

Wayne Huang

over 3 years ago

0 George Mock over 3 years ago

TI__Guru**** 251180 points

This solution presumes the function _c_int00 comes from the compiler RTS library. Inside the SECTIONS directive of the linker command file, create an output section for this purpose. Use lines similar to ...

     for_c_int00
	 {
	    rts*.lib<boot*.obj>(.text)
	 } > FLASH

This creates an output section named for_c_int00. It is composed of one input section. That is the .text input section, from a file with a name that matches the pattern boot*.obj, that comes from a compiler RTS library.

If the function _c_int00 comes from some other place, possibly because of how a software development kit arranges such details, then this solution does not work.

Thanks and regards,

-George

0 Wayne Huang over 3 years ago in reply to George Mock

TI__Genius 16675 points

Dear George,

The user later found that it works by using & for _c_int00, like this

extern uint32_t _c_int00;
#pragma DATA_SECTION(testVar, "testEntryPoint")
#pragma RETAIN(testVar)
volatile const uint32_t testVar = (uint32_t)(&_c_int00);

1. Do you have any comment about the above implementation?

2. Is _c_int00 defined in RTS library? Or is it defined by the linker?

3. We are somewhat confused with the naming. In EABI, we usually find "_" is omitted, but for "_c_int00", "_" is still used before the letter c. Do you know why?

Wayne Huang

+1 George Mock over 3 years ago in reply to Wayne Huang

TI__Guru**** 251180 points

Wayne Huang said:
Do you have any comment about the above implementation?

I take this question from the first post ...

Wayne Huang said:
how the user can place the address value of _c_int00 on a flash location?

... to mean the user wants to control the memory address at which _c_int00 resides. C code similar to ...

testVar = (uint32_t)(&_c_int00);

... doesn't do that. The line ...

#pragma DATA_SECTION(testVar, "testEntryPoint")

... only controls the memory address of testVar. It has no impact on the location of _c_int00.

Wayne Huang said:
Is _c_int00 defined in RTS library? Or is it defined by the linker?

A definition is provided in the RTS library that comes with the compiler. It is possible to provide a custom implementation. I'm not aware of any C28x SDK which does that. But it is always wise to check.

Wayne Huang said:
We are somewhat confused with the naming. In EABI, we usually find "_" is omitted, but for "_c_int00", "_" is still used before the letter c. Do you know why?

It is part of the C standards that names which begin with an underscore character "_" are reserved to the implementation. The name of the entry point _c_int00 is an example of such a name.

Thanks and regards,

-George

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TMS320F280049: How to place _c_int00 on a flash location?