Access WASM module memory

README.md

@@ -92,6 +92,14 @@ Type "help()" for more information.
 16
 ```
 
+## Access WASM module memory
+
+```py
+>>> import cpp
+>>> cpp._memory[4096:4096+32]
+bytearray(b' Blink\x00\xf0\x9f\xa4\xa9 C++ is running!\x00\n\x00\x00\x00')
+```
+
 ## TODO
 
 - [ ] Fix linking with native toolchain ABI
@@ -101,7 +109,6 @@ Type "help()" for more information.
   - [x] Use functions from other modules like `time`, `machine` etc.
   - [x] Implement `millis()`, run Coremark
 - [x] Support memory
-  - [ ] Expose memory to Python
 - [ ] TBD: Support globals
 - [ ] Add RISC-V support: https://github.com/micropython/micropython/pull/15603
 - [ ] Add AArch64 support: https://github.com/micropython/micropython/issues/4176#issuecomment-1657003511

runtime/libc.c

@@ -47,6 +47,13 @@ size_t strlen(const char *str) {
     return (s - str);
 }
 
+int strncmp(const char *_l, const char *_r, size_t n) {
+	const unsigned char *l=(void *)_l, *r=(void *)_r;
+	if (!n--) return 0;
+	for (; *l && *r && n && *l == *r ; l++, r++, n--);
+	return *l - *r;
+}
+
 void abort() {
     mp_printf(&mp_plat_print, "Aborting");
     for(;;) {}  // Wait forever

runtime/runtime.c

@@ -29,6 +29,25 @@ static mp_obj_t loop(void) {
 
 static MP_DEFINE_CONST_FUN_OBJ_0(loop_obj, loop);
 
+// Module Attributes
+
+static mp_obj_t getattr(mp_obj_t attr) {
+    size_t attr_len;
+    char* attr_str = mp_obj_str_get_data(attr, &attr_len);
+    if (!attr_str) {
+        mp_raise_msg(&mp_type_RuntimeError, "Invalid attr");
+        return mp_const_none;
+    }
+    if (!strncmp(attr_str, "_memory", attr_len)) {
+        return mp_obj_new_bytearray_by_ref(module.w2c_memory.size, (void*)(module.w2c_memory.data));
+    } else {
+        mp_raise_msg(&mp_type_RuntimeError, "Unknown attr");
+        return mp_const_none;
+    }
+}
+
+static MP_DEFINE_CONST_FUN_OBJ_1(getattr_obj, getattr);
+
 // Imported Functions
 
 void w2c_wiring_stopWdt(struct w2c_wiring* wiring) {
@@ -96,6 +115,7 @@ mp_obj_t mpy_init(mp_obj_fun_bc_t *self, size_t n_args, size_t n_kw, mp_obj_t *a
     // Make the function available in the module's namespace
     mp_store_global(MP_QSTR_setup, MP_OBJ_FROM_PTR(&setup_obj));
     mp_store_global(MP_QSTR_loop, MP_OBJ_FROM_PTR(&loop_obj));
+    mp_store_global(MP_QSTR___getattr__, MP_OBJ_FROM_PTR(&getattr_obj));
 
     // This must be last, it restores the globals dict
     MP_DYNRUNTIME_INIT_EXIT