src: Add simple example modules in C and Python.

Signed-off-by: Damien George <[email protected]>

Author: dpgeorge

src/README.md

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+In this directory are the custom modules that can be built into the firmware.
+There are examples of modules written in Python and C.

src/cmodules/cexample/micropython.cmake

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+# Create an INTERFACE library for our C module.
+add_library(usermod_cexample INTERFACE)
+
+# Add our source files to the lib
+target_sources(usermod_cexample INTERFACE
+    ${CMAKE_CURRENT_LIST_DIR}/modcexample.c
+)
+
+# Add the current directory as an include directory.
+target_include_directories(usermod_cexample INTERFACE
+    ${CMAKE_CURRENT_LIST_DIR}
+)
+
+# Link our INTERFACE library to the usermod target.
+target_link_libraries(usermod INTERFACE usermod_cexample)

src/cmodules/cexample/micropython.mk

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+# Add all C files to SRC_USERMOD.
+SRC_USERMOD += $(USERMOD_DIR)/modcexample.c

src/cmodules/cexample/modcexample.c

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+// Include MicroPython API.
+#include "py/runtime.h"
+
+// This is the function which will be called from Python as cexample.add_ints(a, b).
+STATIC mp_obj_t example_add_ints(mp_obj_t a_obj, mp_obj_t b_obj) {
+    // Extract the ints from the micropython input objects.
+    int a = mp_obj_get_int(a_obj);
+    int b = mp_obj_get_int(b_obj);
+
+    // Calculate the addition and convert to MicroPython object.
+    return mp_obj_new_int(a + b);
+}
+// Define a Python reference to the function above.
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(example_add_ints_obj, example_add_ints);
+
+// Define all properties of the module.
+// Table entries are key/value pairs of the attribute name (a string)
+// and the MicroPython object reference.
+// All identifiers and strings are written as MP_QSTR_xxx and will be
+// optimized to word-sized integers by the build system (interned strings).
+STATIC const mp_rom_map_elem_t example_module_globals_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_cexample) },
+    { MP_ROM_QSTR(MP_QSTR_add_ints), MP_ROM_PTR(&example_add_ints_obj) },
+};
+STATIC MP_DEFINE_CONST_DICT(example_module_globals, example_module_globals_table);
+
+// Define module object.
+const mp_obj_module_t example_user_cmodule = {
+    .base = { &mp_type_module },
+    .globals = (mp_obj_dict_t *)&example_module_globals,
+};
+
+// Register the module to make it available in Python.
+// Note: the "1" in the third argument means this module is always enabled.
+// This "1" can be optionally replaced with a macro like MODULE_CEXAMPLE_ENABLED
+// which can then be used to conditionally enable this module.
+MP_REGISTER_MODULE(MP_QSTR_cexample, example_user_cmodule, 1);

src/cmodules/cexample2/micropython.cmake

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+# Create an INTERFACE library for our C module.
+add_library(usermod_cexample2 INTERFACE)
+
+# Add our source files to the lib
+target_sources(usermod_cexample2 INTERFACE
+    ${CMAKE_CURRENT_LIST_DIR}/modcexample2.c
+)
+
+# Add the current directory as an include directory.
+target_include_directories(usermod_cexample2 INTERFACE
+    ${CMAKE_CURRENT_LIST_DIR}
+)
+
+# Link our INTERFACE library to the usermod target.
+target_link_libraries(usermod INTERFACE usermod_cexample2)

src/cmodules/cexample2/micropython.mk

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+# Add all C files to SRC_USERMOD.
+SRC_USERMOD += $(USERMOD_DIR)/modcexample2.c

src/cmodules/cexample2/modcexample2.c

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+#include "py/runtime.h"
+
+STATIC mp_obj_t example_sub_ints(mp_obj_t a_obj, mp_obj_t b_obj) {
+    int a = mp_obj_get_int(a_obj);
+    int b = mp_obj_get_int(b_obj);
+    return mp_obj_new_int(a - b);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(example_sub_ints_obj, example_sub_ints);
+
+STATIC const mp_rom_map_elem_t example_module_globals_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_cexample2) },
+    { MP_ROM_QSTR(MP_QSTR_sub_ints), MP_ROM_PTR(&example_sub_ints_obj) },
+};
+STATIC MP_DEFINE_CONST_DICT(example_module_globals, example_module_globals_table);
+
+const mp_obj_module_t example_user_cmodule2 = {
+    .base = { &mp_type_module },
+    .globals = (mp_obj_dict_t *)&example_module_globals,
+};
+
+MP_REGISTER_MODULE(MP_QSTR_cexample2, example_user_cmodule2, 1);

src/utils/xxd.py

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+from machine import mem8, mem16
+
+
+def xxd(addr, num_bytes=64, width=16):
+    for i in range((num_bytes + width - 1) // width):
+        print("%08x:" % (addr + i * width), end="")
+        for j in range(0, width, 2):
+            word = mem16[addr + i * width + j]
+            print(" %02x%02x" % (word & 0xFF, word >> 8), end="")
+        print("  ", end="")
+        for j in range(width):
+            byte = mem8[addr + i * width + j]
+            if 32 <= byte <= 126:
+                print(chr(byte), end="")
+            else:
+                print(".", end="")
+        print()