OK, I see they extended the C language for R30 and R31! I haven't found any good examples were C and assembler are mixed. I have seen statements which say there are multiple ways to accomplish it. It looks like the simplest is to inject assembler code directly into the C code. See page 76. There is also a section on "Intrinsics" on page 89. I think that might be what you are looking for.
On Tuesday, February 9, 2016 at 7:56:44 AM UTC-5, lucas wrote: > > Ah, thank you. These are excellent resources. I think I found the answer > to my first question in the PRU Optimizing C/C++ Compiler v2.1 User Guide: > > Section: 5.7.2 Global Register Variables > > The C/C++ compiler extends the C language by adding a special convention >> to the register storage class specifier to allow the allocation of global >> registers. This special global declaration has the form: register type >> regid The regid parameter can be __R30 and __R31. The identifiers _ _R30 >> and _ _R31 are each bound to their corresponding register R30 and R31, >> respectively. These are control registers and should always be declared as >> volatile. > > > I am still a bit uncertain about the scratch pad. I have a value stored in > a C variable, but how could I copy that value into inline assembler - so > that I can write it to the scratch pad? > > > > On Tuesday, February 9, 2016 at 1:37:14 PM UTC+1, Soapy Smith wrote: >> >> There is a manual for the C compiler and the assembler: >> >> http://processors.wiki.ti.com/index.php/PRU-ICSS >> >> The links are on the right side of the page. >> >> Some of the PRU hardware specific registers are accessed via a large >> union in a header file. It uses structs with "bit fields" so you can >> easily access individual bits in the register. >> Look for a header file called pru_cfg.h. But specifically to your >> question, I'm still trying to figure out how the PRU input and output >> registers R30 and R31 are done in C, as I >> don't see those called out in the header file (in information overload at >> this point!). >> >> Regarding the scratchpad, I believe it can't be accessed via C. However, >> you can embed assembler codes into C source code. >> If you go here: >> >> >> https://training.ti.com/sitara-processors-building-blocks-for-pru-development-summary >> >> Download the firmware development slides and look at page 8. >> >> Regards, >> Greg >> >> -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
