minimal: Add ability and description to build without the compiler.

minimal/README.md

@@ -33,3 +33,15 @@ This version of the build will work out-of-the-box on a pyboard (and
 anything similar), and will give you a MicroPython REPL on UART1 at 9600
 baud.  Pin PA13 will also be driven high, and this turns on the red LED on
 the pyboard.
+
+## Building without the built-in MicroPython compiler
+
+This minimal port can be built with the built-in MicroPython compiler
+disabled.  This will reduce the firmware by about 20k on a Thumb2 machine,
+and by about 40k on 32-bit x86.  Without the compiler the REPL will be
+disabled, but pre-compiled scripts can still be executed.
+
+To test out this feature, change the `MICROPY_ENABLE_COMPILER` config
+option to "0" in the mpconfigport.h file in this directory.  Then
+recompile and run the firmware and it will execute the frozentest.py
+file.

minimal/main.c

@@ -9,6 +9,7 @@
 #include "py/gc.h"
 #include "lib/utils/pyexec.h"
 
+#if MICROPY_ENABLE_COMPILER
 void do_str(const char *src, mp_parse_input_kind_t input_kind) {
     mp_lexer_t *lex = mp_lexer_new_from_str_len(MP_QSTR__lt_stdin_gt_, src, strlen(src), 0);
     if (lex == NULL) {
@@ -28,6 +29,7 @@ void do_str(const char *src, mp_parse_input_kind_t input_kind) {
         mp_obj_print_exception(&mp_plat_print, (mp_obj_t)nlr.ret_val);
     }
 }
+#endif
 
 static char *stack_top;
 static char heap[2048];
@@ -40,6 +42,7 @@ int main(int argc, char **argv) {
     gc_init(heap, heap + sizeof(heap));
     #endif
     mp_init();
+    #if MICROPY_ENABLE_COMPILER
     #if MICROPY_REPL_EVENT_DRIVEN
     pyexec_event_repl_init();
     for (;;) {
@@ -53,6 +56,9 @@ int main(int argc, char **argv) {
     #endif
     //do_str("print('hello world!', list(x+1 for x in range(10)), end='eol\\n')", MP_PARSE_SINGLE_INPUT);
     //do_str("for i in range(10):\r\n  print(i)", MP_PARSE_FILE_INPUT);
+    #else
+    pyexec_frozen_module("frozentest.py");
+    #endif
     mp_deinit();
     return 0;
 }

minimal/mpconfigport.h

@@ -2,6 +2,11 @@
 
 // options to control how Micro Python is built
 
+// You can disable the built-in MicroPython compiler by setting the following
+// config option to 0.  If you do this then you won't get a REPL prompt, but you
+// will still be able to execute pre-compiled scripts, compiled with mpy-cross.
+#define MICROPY_ENABLE_COMPILER     (1)
+
 #define MICROPY_QSTR_BYTES_IN_HASH  (1)
 #define MICROPY_QSTR_EXTRA_POOL     mp_qstr_frozen_const_pool
 #define MICROPY_ALLOC_PATH_MAX      (256)