Compiler/TMS320F28379D: Linker Command File Union Syntax

Ed Sanders

Tool/software: TI C/C++ Compiler

Greetings,

I generated a linker command file using a union construct. In the hopes of not needing to specify the object file etc for each entry in the union, I tried removing that information. The linker accepted it and produced the output. Is this the expected result? If the code contained more than one place with a given name, would they simply be concatenated? I guess I’m going beyond the basics now. Is there any documentation which could help? The syntax used is below:

UNION

{

NAME1

NAME2

} > MEMORY_VALUE, PAGE = 1

Thank you,

over 5 years ago

0 KARTHIKEYAN RAJAMANICKAM over 5 years ago

TI__Genius 11645 points

Hello Ed,

You can look at the below 2 links to understand this better,

processors.wiki.ti.com/.../C28x_Compiler_-_Understanding_Linking

www.ti.com/.../spru513p.pdf

Hope this helps.

0 Ed Sanders over 5 years ago in reply to KARTHIKEYAN RAJAMANICKAM

Genius 4105 points

Hi Karthik,

The website has some good introductory information. I have been using spru513s.pdf, a bit more recent, and all the examples of UNIONs include the {<Object File Name>(<Section Name>} construct. In our case, we want to omit that construct, and use the DATA_SECTION pragma name only so that we do not need to specify an object file. This would allow us to use the same cmd file in projects which define that space using different object files.

Trying it with the omission seems to work (We need to do more testing.). So I am looking for some documentation which confirms that this, indeed, will work.

Thank you,

0 George Mock over 5 years ago

TI__Guru**** 252400 points

Another good introduction article is Linker Command File Primer. Focus on the first half.

The following is valid ...

Ed Sanders said:

UNION

{

NAME1

NAME2

} > MEMORY_VALUE, PAGE = 1

Here is what it does. A UNION is a collection of output sections that all start at the same address. That is, the output sections are overlaid on top of each other in memory. The linker provides no features for managing this overlay. That remains the responsibility of the team which implements the program. NAME1 creates an output section of that name. It is made up of all the input sections also named NAME1. The same is true of NAME2. This UNION is allocated to the memory range named MEMORY_VALUE located on PAGE 1.

Thanks and regards,

-George

0 Ed Sanders over 5 years ago in reply to George Mock

Genius 4105 points

Hi George,

This makes sense. Thanks for your help.

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Compiler/TMS320F28379D: Linker Command File Union Syntax