py: Overhaul and simplify printf/pfenv mechanism.

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.

1 files changed, 2 insertions, 2 deletions

diff --git a/stmhal/servo.c b/stmhal/servo.c
index a9b37a54f3..4c4f95da4f 100644
--- a/stmhal/servo.c
+++ b/stmhal/servo.c
@@ -178,9 +178,9 @@ STATIC mp_obj_t pyb_pwm_set(mp_obj_t period, mp_obj_t pulse) {
 
 MP_DEFINE_CONST_FUN_OBJ_2(pyb_pwm_set_obj, pyb_pwm_set);
 
-STATIC void pyb_servo_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
+STATIC void pyb_servo_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
     pyb_servo_obj_t *self = self_in;
-    print(env, "<Servo %lu at %luus>", self->servo_id, 10 * self->pulse_cur);
+    mp_printf(print, "<Servo %lu at %luus>", self->servo_id, 10 * self->pulse_cur);
 }
 
 /// \classmethod \constructor(id)