C in hal

I am thinking of moving clockcalc to C for the VOP, HDMI.
It shouldn’t use any clib , just standard arithmetic operations , and memory writes.
Is that OK?

OK in which respect? If you can get it working correctly, please post results. Definitely not saying it’s not possible. It’s just I couldn’t get it working right is all.

Using C in the HAL should be fine, as long as you know what you’re doing. See Using C in assembler components.

• Create a C version of the HAL’s static workspace struct, expose it to the C code via “__global_reg(6) halworkspace_t *sb”, and use that for storing any global variables. Regular (non-const) C global/static variables won’t work because the compiler won’t know how to relocate them. Make sure the assembler & C versions of the struct definition are kept in sync!
• Don’t use any C library functions (unless you feel like implementing your own version of them within the HAL)
• You might need to add implementations of some support functions required by the compiler
• Avoid using C prior to MMU activation, because the compiler can’t generate read-only position-independent code (normally the C code that’s built into the HAL will be compiled as if it’s running at the usual logical address that ROM images are loaded at)

If you can get it working correctly, please post results. Definitely not saying it’s not possible. It’s just I couldn’t get it working right is all.

I think most of your problems stemmed from the fact that you were trying to use GCC (and maybe also using C pre-MMU?). I think pretty much every HAL uses at least some C code (via Norcroft) without any major issues.

I have Done something tests now and it works. But the makefile system tries to build My c code as an application. Howver IF i compiled it manually ie cc -c c.clkconfig IT worked. I missed two functions from clib. Handling division by zero and overflow from division. I just implemented them as dummys. writing on iPad , sorry fot mistakes.

About global variables . I have some and i havent notice erors from IT. But I have other issues so I think i replace them with #defines .