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How Relevant are C Portability Pitfalls?

An article about C Portability Lessons for Weird Machines has been making the headlines on the Interwebs lately. It’s full of interesting examples, though none of them are from machines relevant to the last two decades of high-end computing.

I think these lessons are still relevant today, though, and that you should still pay attention to them, and that you  should still write “proper” code. Here is why.

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DMA-based SPI on SHARC ADSP-21489

If you have resorted to Google after having uselessly pored over AD’s reference manuals, hoping to find at least a proper hint about how to approach this, if not a bit of code, it’s OK, you can stop now. It’s right here. Your quest is complete.

In the hope that no poor soul will have to bang his head against the desk trying to piece together the countless pieces of this puzzle, I did a quick write-up to show you how to do SPI communication with DMA on ADSP-21489. This should probably work (with obvious adaptation) on any DSP in the same family, and it should be easy to adapt if your DSP is the SPI slave, not the master, as below.

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