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.

2 files changed, 4 insertions, 2 deletions

diff --git a/minimal/main.c b/minimal/main.c
index 1d600d584..29b5af1af 100644
--- a/minimal/main.c
+++ b/minimal/main.c
@@ -6,7 +6,6 @@
 #include "py/compile.h"
 #include "py/runtime.h"
 #include "py/repl.h"
-#include "py/pfenv.h"
 #include "py/gc.h"
 #include "pyexec.h"
 
@@ -26,7 +25,7 @@ void do_str(const char *src) {
         nlr_pop();
     } else {
         // uncaught exception
-        mp_obj_print_exception(printf_wrapper, NULL, (mp_obj_t)nlr.ret_val);
+        mp_obj_print_exception(&mp_plat_print, (mp_obj_t)nlr.ret_val);
     }
 }
 
diff --git a/minimal/mpconfigport.h b/minimal/mpconfigport.h
index 02ad5bd62..b08bdf8b7 100644
--- a/minimal/mpconfigport.h
+++ b/minimal/mpconfigport.h
@@ -60,6 +60,9 @@ typedef void *machine_ptr_t; // must be of pointer size
 typedef const void *machine_const_ptr_t; // must be of pointer size
 typedef long mp_off_t;
 
+void mp_hal_stdout_tx_strn_cooked(const char *str, mp_uint_t len);
+#define MP_PLAT_PRINT_STRN(str, len) mp_hal_stdout_tx_strn_cooked(str, len)
+
 // extra built in names to add to the global namespace
 extern const struct _mp_obj_fun_builtin_t mp_builtin_open_obj;
 #define MICROPY_PORT_BUILTINS \