These were copied from the stm32 port (then stmhal) at the very beginning
of this port, with the anticipation that the esp8266 port would have board
definition files with a list of valid pins and their names. But that has
not been implemented and likely won't be, so remove the corresponding lines
from the Makefile.
This patch adds in internal config value MICROPY_HW_ENABLE_HW_I2C that is
automatically configured, and enabled only if one or more hardware I2C
ports are defined in the mpconfigboard.h file. If none are defined then
the pyb.I2C class is excluded from the build, along with all supporting
code. The machine.I2C class will still be available for software I2C.
Disabling all hardware I2C on an F4 board saves around 10,000 bytes of code
and 200 bytes of RAM.
Each NLR implementation (Thumb, x86, x64, xtensa, setjmp) duplicates a lot
of the NLR code, specifically that dealing with pushing and popping the NLR
pointer to maintain the linked-list of NLR buffers. This patch factors all
of that code out of the specific implementations into generic functions in
nlr.c. This eliminates duplicated code.
The factoring also allows to make the machine-specific NLR code pure
assembler code, thus allowing nlrthumb.c to use naked function attributes
in the correct way (naked functions can only have basic inline assembler
code in them).
There is a small overhead introduced (typically 1 machine instruction)
because now the generic nlr_jump() must call nlr_jump_tail() rather than
them being one combined function.