TMS320F28384S: The pointer size.

Luke Chen

Part Number: TMS320F28384S

Hi champs,

According to the compiler user's guide, pointer sizes for CLA are always 16-bits, the C28x supports 32-bit pointers.

So, the maximum pointer size of C28x and CM4 are 32-bit, is this correct? Is this a hardware or compiler limitation please?

Regards,

Luke

over 4 years ago

0 Ashwini Athalye over 4 years ago

TI__Expert 7705 points

Hi Luke,

This difference between C28 and CLA comes from the architecture. Please see the following link in the CLA software development guide for more information:

https://software-dl.ti.com/C2000/docs/cla_software_dev_guide/faq.html?highlight=pointer#how-are-data-types-different-on-c28x-and-cla

Thanks,

Ashwini

0 Luke Chen over 4 years ago in reply to Ashwini Athalye

TI__Expert 5090 points

Hi Ashwini,

The maximum pointer sizes of C28x and CM4 are 32-bits and this is the limitation of the architecture, is it correct please?

Regards,

Luke

+1 Ashwini Athalye over 4 years ago in reply to Luke Chen

TI__Expert 7705 points

Hi Luke,

Yes, The pointer size is 32-bits always for C28x and M4 due to the CPU architecture. Note: There is no minimum or maximum size for pointers, the pointer size will always be 32-bit for C28x and M4 and 16-bit for CLA.

Thanks,

Ashwini

0 Luke Chen over 4 years ago in reply to Ashwini Athalye

TI__Expert 5090 points

Ashwini,

If customers use below C statements,

value1 = (uint64_t *)address1;

value2 = (uint32_t *)address2;

Should address1 and address2 be aligned? For example, aligned to 128-bit or 64-bit?

Regards,

Luke

0 Ashwini Athalye over 4 years ago in reply to Luke Chen

TI__Expert 7705 points

Hi Luke,

Let me ask the experts and get back to you.

Thanks,
Ashwini

0 Luke Chen over 4 years ago in reply to Ashwini Athalye

TI__Expert 5090 points

Hi Ashwini,

Any feedback from the experts please?

Thanks,

Luke

0 Ashwini Athalye over 4 years ago in reply to Luke Chen

TI__Expert 7705 points

Hi Luke,

I apologize, I have not heard back from the team yet, I am following up.

Thanks,
Ashwini

+1 Ashwini Athalye over 4 years ago in reply to Ashwini Athalye

TI__Expert 7705 points

Hi Luke,

In the above example code you have provided, address1 and address2 must be 32-bit aligned and the user must ensure this.

The C28 treats 64-bit accesses as 2 32-bit accesses hence even though address1 is being used as a 64-bit pointer, the alignment needs to be 32-bit.

Hope this helps and sorry for the delay in getting back to you.

Thanks,

Ashwini

0 Luke Chen over 4 years ago in reply to Ashwini Athalye

TI__Expert 5090 points

Ashwini,

I see, thanks for help.

Regards,

Luke

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TMS320F28384S: The pointer size.