On Friday 06 December 2002 06:53, [email protected] wrote:
> I have a lot of data to write to the information memory and want to use the
> Block write rather than single byte write. This means I have to execute out
> of RAM while the write is happening. Any clues as to how to do this?
You can execute a code located in RAM at any time. But first, you have to copy
this func there. To copy the function to RAM, you need to know its size and a
pointer.
Consider the following:
---------------------------------------------------------------------------
type_f func_to_be_execed_from_ram(params p1, ...)
{
// func body.
// make sure there are no long branches
// or _relative_ (pc) calls (gcc does not issue them).
}
void dummy_func() {
// must exists and be empty cause we need this function to
// determine previous' one size.
}
void this_func_copies_another_to_ram(void *dst, void *src, size_t size)
{
// memcpy(dst,src,size) can be a good choise
}
void *prepare_copy()
{
void *dst;
size_t size;
extern char __bss_end; // this var defined by linker. read docs for
more
info.
size = (char *)&dummy_func - (char *)&func_to_be_execed_from_ram;
dst = (char *)&__bss_end + size;
this_func_copies_another_to_ram(dst, &func_to_be_execed_from_ram, size);
return dst;
}
void (*copier)();
int main()
{
copier = prepare_copy();
copier();
return 240;
}
> My plan is to define a function pointer to the writing function in ROM and
> use that to copy the function to a location in RAM. The location in RAM
> will also be a function pointer so it is just a matter of executing the
> function in RAM at the pointer. My problem is, how do I know how big the
> function is to work out the copy size? Has anyone managed this?
>
Do not pass -ffunction-sections flag to compiler.
Hope this helps,
~d
> Brian Smith
> Australia
>
>
>
>
>
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