Set file system size.

inc/microbit/memory.h

@@ -28,7 +28,7 @@
 #define __MICROPY_INCLUDED_MEMORY_H__
 
 #include "microbit/filesystem.h"
-
+#include "emscripten.h"
 
 static inline char *rounddown(char *addr, uint32_t align) {
     return (char *)(((uint32_t)addr)&(-align));
@@ -38,19 +38,28 @@ static inline char *roundup(char *addr, uint32_t align) {
     return (char *)((((uint32_t)addr)+align-1)&(-align));
 }
 
-char rom[0x6400] __attribute__((aligned(MBED_CONF_APP_MICROBIT_PAGE_SIZE)));
+static uint32_t end_of_code = 0;
+
+#define ROM_SIZE ((CHUNK_SIZE * MAX_CHUNKS_IN_FILE_SYSTEM) + (2 * MBED_CONF_APP_MICROBIT_PAGE_SIZE))
+static char rom[ROM_SIZE] __attribute__((aligned(MBED_CONF_APP_MICROBIT_PAGE_SIZE)));
+
+EMSCRIPTEN_KEEPALIVE
+void set_filesystem_size(uint32_t size) {
+    int32_t temp = ROM_SIZE - size;
+    end_of_code = temp < 0 ? 0 : temp;
+}
 
 /** The end of the code area in flash ROM (text plus read-only copy of data area) */
 static inline char *microbit_end_of_code() {
-    return  &rom[0x0]; // 0x39C00 - 0x39C00
+    return  &rom[end_of_code];
 }
 
 static inline char *microbit_end_of_rom() {
-    return &rom[0x6400]; // 0x40000 - 0x39C00
+    return &rom[ROM_SIZE];
 }
 
 static inline char *microbit_mp_appended_script() {
-    return  &rom[0x4400]; // 0x3e000 - 0x39C00
+    return  &rom[ROM_SIZE - (8 * MBED_CONF_APP_MICROBIT_PAGE_SIZE)];
 }
 
 static inline void *microbit_compass_calibration_page(void) {