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, 0 deletions

diff --git a/unix/mpconfigport.h b/unix/mpconfigport.h
index 00cb12139d..694db88fc1 100644
--- a/unix/mpconfigport.h
+++ b/unix/mpconfigport.h
@@ -170,6 +170,8 @@ void mp_unix_mark_exec(void);
 #define MP_PLAT_ALLOC_EXEC(min_size, ptr, size) mp_unix_alloc_exec(min_size, ptr, size)
 #define MP_PLAT_FREE_EXEC(ptr, size) mp_unix_free_exec(ptr, size)
 
+#define MP_PLAT_PRINT_STRN(str, len) fwrite(str, 1, len, stdout)
+
 extern const struct _mp_obj_fun_builtin_t mp_builtin_input_obj;
 extern const struct _mp_obj_fun_builtin_t mp_builtin_open_obj;
 #define MICROPY_PORT_BUILTINS \