pybricks.common.System: Support user data storage.

This allows end-users to save small amounts of data on the hub. This
is useful for settings like train speed or counters in great ball
contraption modules.

Fixes pybricks/support#85

lib/pbio/include/pbsys/program_load.h

@@ -53,10 +53,24 @@ typedef struct _pbsys_program_load_data_header_t {
 
 #define PBSYS_PROGRAM_LOAD_MAX_PROGRAM_SIZE (PBSYS_CONFIG_PROGRAM_LOAD_ROM_SIZE - sizeof(pbsys_program_load_data_header_t))
 
+pbio_error_t pbsys_program_load_set_user_data(uint32_t offset, const uint8_t *data, uint32_t size);
+
+pbio_error_t pbsys_program_load_get_user_data(uint32_t offset, uint8_t **data, uint32_t size);
+
 #else
 
 #define PBSYS_PROGRAM_LOAD_MAX_PROGRAM_SIZE (0)
 
+static inline pbio_error_t pbsys_program_load_set_user_data(uint32_t offset, const uint8_t *data, uint32_t size) {
+    return PBIO_ERROR_NOT_SUPPORTED;
+}
+
+static inline pbio_error_t pbsys_program_load_get_user_data(uint32_t offset, uint8_t **data, uint32_t size) {
+    *data = NULL;
+    return PBIO_ERROR_NOT_SUPPORTED;
+}
+
+
 #endif // PBSYS_CONFIG_PROGRAM_LOAD
 
 #endif // _PBSYS_PROGRAM_LOAD_H_

lib/pbio/sys/program_load.c

@@ -46,6 +46,42 @@ static void update_write_size(void) {
     map->header.write_size = sizeof(pbsys_program_load_data_header_t) + map->header.program_size;
 }
 
+/**
+ * Saves user data. This will be saved during power off, like program data.
+ *
+ * @param [in]  offset  Offset from the base address.
+ * @param [in]  data    The data to be stored (copied).
+ * @param [in]  size    Data size.
+ * @returns             ::PBIO_ERROR_INVALID_ARG if the data won't fit.
+ *                      Otherwise, ::PBIO_SUCCESS.
+ */
+pbio_error_t pbsys_program_load_set_user_data(uint32_t offset, const uint8_t *data, uint32_t size) {
+    if (offset + size > sizeof(map->header.user_data)) {
+        return PBIO_ERROR_INVALID_ARG;
+    }
+    // Update data and write size to request write on poweroff.
+    memcpy(map->header.user_data + offset, data, size);
+    update_write_size();
+    return PBIO_SUCCESS;
+}
+
+/**
+ * Gets pointer to user data.
+ *
+ * @param [in]  offset  Offset from the base address.
+ * @param [in]  data    The data reference.
+ * @param [in]  size    Data size.
+ * @returns             ::PBIO_ERROR_INVALID_ARG if reading out of range.
+ *                      Otherwise, ::PBIO_SUCCESS.
+ */
+pbio_error_t pbsys_program_load_get_user_data(uint32_t offset, uint8_t **data, uint32_t size) {
+    if (offset + size > sizeof(map->header.user_data)) {
+        return PBIO_ERROR_INVALID_ARG;
+    }
+    *data = map->header.user_data + offset;
+    return PBIO_SUCCESS;
+}
+
 static bool pbsys_program_load_start_user_program_requested;
 static bool pbsys_program_load_start_repl_requested;
 

pybricks/common/pb_type_system.c

@@ -8,12 +8,16 @@
 #include <string.h>
 
 #include <pbdrv/bluetooth.h>
+#include <pbsys/program_load.h>
 
 #include "py/obj.h"
+#include "py/objstr.h"
 #include "py/runtime.h"
 
 #include <pybricks/common.h>
 #include <pybricks/util_pb/pb_error.h>
+#include <pybricks/util_mp/pb_kwarg_helper.h>
+#include <pybricks/util_mp/pb_obj_helper.h>
 
 STATIC mp_obj_t pb_type_System_name(void) {
     const char *hub_name = pbdrv_bluetooth_get_hub_name();
@@ -101,6 +105,34 @@ STATIC mp_obj_t pb_type_System_shutdown(void) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(pb_type_System_shutdown_obj, pb_type_System_shutdown);
 
+STATIC mp_obj_t pb_type_System_storage(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    PB_PARSE_ARGS_FUNCTION(n_args, pos_args, kw_args,
+        PB_ARG_REQUIRED(offset),
+        PB_ARG_DEFAULT_NONE(read),
+        PB_ARG_DEFAULT_NONE(write));
+
+    // Get offset and confirm integer type.
+    mp_int_t offset = mp_obj_get_int(offset_in);
+
+    // Handle read.
+    if (write_in == mp_const_none) {
+        byte *data;
+        mp_uint_t size = mp_obj_get_int(read_in);
+        pb_assert(pbsys_program_load_get_user_data(offset, &data, size));
+        return mp_obj_new_bytes(data, size);
+    }
+
+    // Handle write.
+    if (read_in == mp_const_none && !mp_obj_is_str(write_in) && mp_obj_is_str_or_bytes(write_in)) {
+        mp_obj_str_t *obj = ((mp_obj_str_t *)MP_OBJ_TO_PTR(write_in));
+        pbsys_program_load_set_user_data(offset, obj->data, obj->len);
+        return mp_const_none;
+    }
+
+    mp_raise_ValueError(MP_ERROR_TEXT("Must set either read (int) or write (bytes)."));
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pb_type_System_storage_obj, 0, pb_type_System_storage);
+
 #endif // PBIO_CONFIG_ENABLE_SYS
 
 // dir(pybricks.common.System)
@@ -113,6 +145,7 @@ STATIC const mp_rom_map_elem_t common_System_locals_dict_table[] = {
     #if PBIO_CONFIG_ENABLE_SYS
     { MP_ROM_QSTR(MP_QSTR_set_stop_button), MP_ROM_PTR(&pb_type_System_set_stop_button_obj) },
     { MP_ROM_QSTR(MP_QSTR_shutdown), MP_ROM_PTR(&pb_type_System_shutdown_obj) },
+    { MP_ROM_QSTR(MP_QSTR_storage), MP_ROM_PTR(&pb_type_System_storage_obj) },
     #endif
 };
 STATIC MP_DEFINE_CONST_DICT(common_System_locals_dict, common_System_locals_dict_table);