TMS320F28388D: ARM Calling Convention

Ed Sanders

Part Number: TMS320F28388D

Greetings,

For performance reasons, I need to write a bit of code in assembly and call it from our C++ code. I have looked in the ARM documentation I have collected so far, but haven’t been able to find anything on the calling convention. Where can I find that info?

Thank you,

over 1 year ago

0 Allison Nguyen over 1 year ago

TI__Mastermind 24900 points

Hi Ed,

If you take a look here: https://www.ti.com/lit/ml/swrp141/swrp141.pdf, you can see that the 'BL' instruction is used in the ARM Architecture to branch (with link). Also found an article that discusses this as well in case you find it helpful: https://open4tech.com/function-calls-on-arm-cortex-m-microprocessors/ and there is an Arm instruction set card online: https://developer.arm.com/documentation/qrc0001/m.

The C28x equivalent is a long call ('LC') - here is the C28x instruction set as well: https://www.ti.com/lit/ug/spru430f/spru430f.pdf.

Best Regards,

Allison

0 Ed Sanders over 1 year ago in reply to Allison Nguyen

Genius 4105 points

Hi Allison,

The second link provided a little help. It talks about the marshalling of the arguments which is part of what I am interested in. Specifically, I need to know how the ARM compiler sends arguments to the called function, and also where it looks to receive the return value. The article says that there is no standard for those. So it becomes a question of what does the TI ARM compiler do and expect.

Thank you,

0 George Mock over 1 year ago in reply to Ed Sanders

TI__Guru**** 251740 points

I presume you use the TI Arm compiler, and not the TI Arm Clang compiler. Please search the TI ARM compiler manual for the sub-chapter titled Accessing Assembly Language Functions From C/C++.

Thanks and regards,

-George

0 Ed Sanders over 1 year ago in reply to George Mock

Genius 4105 points

Hi George,

I have been using the default compiler which turns out to be the TI ARM compiler.

In the document, I can see a piece of what I am looking for. In the last paragraph of that section, it states that the parameter is passed in R0 and the return value is in R0. Is there something which describes how additional parameters are passed?

Thank you,

+1 George Mock over 1 year ago in reply to Ed Sanders

TI__Guru**** 251740 points

Please search the TI ARM compiler manual for the sub-chapter titled Register Conventions.

Thanks and regards,

-George

0 Ed Sanders over 1 year ago in reply to George Mock

Genius 4105 points

Perfect! Thank you George.

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TMS320F28388D: ARM Calling Convention