py/mphal.h contains declarations for generic mp_hal_XXX functions, such
as stdio and delay/ticks, which ports should provide definitions for. A
port will also provide mphalport.h with further HAL declarations.
Previous to this patch the printing mechanism was a bit of a tangled
mess. This patch attempts to consolidate printing into one interface.
All (non-debug) printing now uses the mp_print* family of functions,
mainly mp_printf. All these functions take an mp_print_t structure as
their first argument, and this structure defines the printing backend
through the "print_strn" function of said structure.
Printing from the uPy core can reach the platform-defined print code via
two paths: either through mp_sys_stdout_obj (defined pert port) in
conjunction with mp_stream_write; or through the mp_plat_print structure
which uses the MP_PLAT_PRINT_STRN macro to define how string are printed
on the platform. The former is only used when MICROPY_PY_IO is defined.
With this new scheme printing is generally more efficient (less layers
to go through, less arguments to pass), and, given an mp_print_t*
structure, one can call mp_print_str for efficiency instead of
mp_printf("%s", ...). Code size is also reduced by around 200 bytes on
Thumb2 archs.
Teensy doesn't need to worry about overflows since all of
its timers are only 16-bit.
For PWM, the pulse width needs to be able to vary from 0..period+1
(pulse-width == period+1 corresponds to 100% PWM)
I couldn't test the 0xffffffff cases since we can't currently get a
period that big in python. With a prescaler of 0, that corresponds
to a freq of 0.039 (i.e. cycle every 25.56 seconds), and we can't
set that using freq or period.
I also tested both stmhal and teensy with floats disabled, which
required a few other code changes to compile.
These functions are generally 1 machine instruction, and are used in
critical code, so makes sense to have them inline.
Also leave these functions uninverted (ie 0 means enable, 1 means
disable) and provide macro constants if you really need to distinguish
the states. This makes for smaller code as well (combined with
inlining).
Applied to teensy port as well.
Because (for Thumb) a function pointer has the LSB set, pointers to
dynamic functions in RAM (eg native, viper or asm functions) were not
being traced by the GC. This patch is a comprehensive fix for this.
Addresses issue #820.
Conflicts:
stmhal/pin_named_pins.c
stmhal/readline.c
Renamed HAL_H to MICROPY_HAL_H. Made stmhal/mphal.h which intends to
define the generic Micro Python HAL, which in stmhal sits above the ST
HAL.
Paul Sokolovsky