`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.
The current ISR implementation for AVR8 requires use of
avr8_[enter/exit]_isr pair which add some boilerplate on code.
This add AVR8_ISR which clean-up the code and make it simpler
and hides any schedule detail from the user perspective.
This is a preparation for future scheduling and irq optimizations.
Signed-off-by: Gerson Fernando Budke <nandojve@gmail.com>
The avr8_state variable uses bit operation to set/clear the state. This
rework avr8_state to use increment/decrement instead. It introduce the
use of General Purpose IO Register 1 (GPIOR1) when available.
This is a preparation for future scheduling and irq optimizations.
Signed-off-by: Gerson Fernando Budke <nandojve@gmail.com>
The avr8_state store state information used to determine scheduling
and uart irq. This move all uart irq states to avr8_state_uart
variable. It introduce the use of General Purpose IO Register 0
(GPIOR0) when available and now all uarts from xmega can be used.
This is a preparation for future scheduling and irq optimizations.
Signed-off-by: Gerson Fernando Budke <nandojve@gmail.com>
This allows automatically moving format strings to flash, provided that
code previously compiled fine with `-Wformat-nonliteral` (which in RIOT
is the case due to `-Wformat=2`).
This adds a layer of convenience abstraction over classical Harvard
architectures (like most AVRs) that do not map the flash memory into
the data address space and modern Harvard architectures or von-Neumann
architectures that do so. The motivation is to safe a lot of RAM for
AVR by storing constant strings into flash.
ATxmega have many clock options. This introduce clk_init into cpu_init
to allow user select between a default configuration or perform fine
clock tune.
Signed-off-by: Gerson Fernando Budke <nandojve@gmail.com>
The ATxmega can have up to 8 UARTs. This increase from 2 up to 7 to
keep avr8_state flags with 8 bits wide.
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>
