I'm mostly doing PIC32 stuff now with C32, the linker, etc. I do a little
assembly for it, but very little. I find linker scripts very cryptic. It'd
sure be nice if they were commented a bit more. It'd also be nice to
easily define the address where a function is to be placed. The new
version of C32 has an attribute that allows this, but it appears there are
various issues with this new version (especially in printf).

In my bootloader, I'd like to have a jump table at a specific address that
does not move as I make code changes. I see how I could do it in assembly
(including use of org, which, it appears, is based on the section start,
not the absolute address), but it'd be nice to be able to do it in C.
Something like:

org SomeAbsoluteVirtualAddress
function1: goto LocalFunction1;
Function2: goto LocalFunction2;
Function3: goto LocalFunction3;

The "LocalFunctions" would still do all the stack operations (getting
parameters, allocating local variables, cleaning up the stack, etc.). The
jump table would just provide a fixed address to access the function.

I did this on the PIC24, building my own interrupt jump table since the
PIC24 places the interrupt vector table in the boot section. I just had
all those original interrupt vectors point into my jump table, which then
pointed to the actual interrupt function. I THINK I did it in C (I'll have
to look at the code), but MAY have done it in assembly.

I tried the above stuff (
function1: goto LocalFunction1;
Function2: goto LocalFunction2;
Function3: goto LocalFunction3;
), but the C32 compiler did not like it. I don't think it liked the labels
(expecting a return value type instead). For now, I've put functions that
call local functions at the top of the section, but that uses more stack
space and is pretty inefficient.

So... how do I do a jump table in C32? Or do I go back to assembly?

THANKS!

Harold


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