`flash_<funcname>()` is implemented by `<funcname>_P()` provided by
the AVR libc on AVR targets. Previously, the preprocessor was used
to do the aliasing, but this causes issues with LLVM: The signatures of
e.g. `printf_P()` expects `const char *`, whereas flash utils expects
`FLASH_ATTR const char *`. For GCC this will just implicitly drop the
`FLASH_ATTR`, while it requires an explicit cast for LLVM.
To implement the explicit cast, `static inline` function wrappers
where used instead where possible. But for the variadic functions
(e.g. `printf(fmt, ...)`) the linker is used to provide the aliases,
as there is no way to pass the variadic functions throw in C. The
alternative would be to implement `flash_printf()` by calling
`vprintf_P()`, but that increased ROM size quite a bit.
Finally, a work around for a bug in Ubuntu's toolchain has been added:
An unused function that calls to `printf_P()`, `fprintf_P()` and
`snprintf_P()`. Since this function is garbage collected anyway, it
has no impact on the generated ELF file.
Atmel AVR-8 CPU was reworked to accomodate variants like ATxmega.
This rename to atmega.inc.mk to avr8.inc.mk to be compliant with
new directory structure.
Signed-off-by: Gerson Fernando Budke <nandojve@gmail.com>
Split atmega_common code into avr8_common folder. This moves common
avr8 code to be used for all avr8 variants: tiny, mega and xmega.
Signed-off-by: Gerson Fernando Budke <nandojve@gmail.com>
