AP_Scripting: Support sending MAVLink buffers from scripts

libraries/AP_Scripting/AP_Scripting.cpp

@@ -140,6 +140,8 @@ AP_Scripting::AP_Scripting() {
     }
 #endif // CONFIG_HAL_BOARD == HAL_BOARD_SITL
     _singleton = this;
+
+    memset(mavlink_data.accept_msg_ids, -1, sizeof(mavlink_data.accept_msg_ids));
 }
 
 void AP_Scripting::init(void) {
@@ -338,6 +340,54 @@ void AP_Scripting::restart_all()
     _stop = true;
 }
 
+void AP_Scripting::handle_message(const mavlink_message_t &msg, const mavlink_channel_t chan) {
+    if (mavlink_data.input == nullptr) {
+        return;
+    }
+
+    struct mavlink_msg data {msg, chan};
+
+    WITH_SEMAPHORE(mavlink_data.sem);
+
+    for (int32_t id : mavlink_data.accept_msg_ids) {
+        if (id == -1) {
+            return;
+        }
+        if (id == msg.msgid) {
+            mavlink_data.input->push(data);
+            return;
+        }
+    }
+}
+
+void AP_Scripting::send_message(const mavlink_channel_t chan) {
+    if (mavlink_data.output == nullptr) {
+        return;
+    }
+
+    struct mavlink_output data;
+    if (mavlink_data.output->peek(data) && (data.chan == chan)) {
+        // FIXME: The data thats in this mavlink_msg_entry_t should be provided from the script, which allows
+        //        sending entirely new messages as outputs. At the moment we can only encode messages that
+        //        are known at compile time. This is fine as a starting point as this is symmetrical to the
+        //        decoding side of the scripting support
+        const mavlink_msg_entry_t *entry = mavlink_get_msg_entry(data.msgid);
+        if (entry == nullptr) {
+            return;
+        }
+        if (comm_get_txspace(chan) >= (GCS_MAVLINK::packet_overhead_chan(chan) + entry->max_msg_len)) {
+            _mav_finalize_message_chan_send(chan,
+                                            entry->msgid,
+                                            data.data,
+                                            entry->min_msg_len,
+                                            entry->max_msg_len,
+                                            entry->crc_extra);
+
+            UNUSED_RESULT(mavlink_data.output->pop(data));
+        }
+    }
+}
+
 AP_Scripting *AP_Scripting::_singleton = nullptr;
 
 namespace AP {