HAL_SITL: allow SITL to use SERIALn_PROTOCOL=23

this allows for testing of RC input protocol parsing in SITL

libraries/AP_HAL_SITL/RCInput.cpp

@@ -3,6 +3,7 @@
 
 #include "RCInput.h"
 #include <SITL/SITL.h>
+#include <AP_RCProtocol/AP_RCProtocol.h>
 
 using namespace HALSITL;
 
@@ -10,10 +11,19 @@ extern const AP_HAL::HAL& hal;
 
 void RCInput::init()
 {
+    AP::RC().init();
 }
 
 bool RCInput::new_input()
 {
+    if (!using_rc_protocol) {
+        if (AP::RC().new_input()) {
+            using_rc_protocol = true;
+        }
+    }
+    if (using_rc_protocol) {
+        return AP::RC().new_input();
+    }
     if (_sitlState->new_rc_input) {
         _sitlState->new_rc_input = false;
         return true;
@@ -23,6 +33,9 @@ bool RCInput::new_input()
 
 uint16_t RCInput::read(uint8_t ch)
 {
+    if (using_rc_protocol) {
+        return AP::RC().read(ch);
+    }
     if (ch >= num_channels()) {
         return 0;
     }
@@ -42,6 +55,9 @@ uint8_t RCInput::read(uint16_t* periods, uint8_t len)
 
 uint8_t RCInput::num_channels()
 {
+    if (using_rc_protocol) {
+        return AP::RC().num_channels();
+    }
     SITL::SITL *_sitl = AP::sitl();
     if (_sitl) {
         return MIN(_sitl->rc_chancount.get(), SITL_RC_INPUT_CHANNELS);

libraries/AP_HAL_SITL/RCInput.h

@@ -20,6 +20,7 @@ public:
 
 private:
     SITL_State *_sitlState;
+    bool using_rc_protocol;
 };
 
 #endif

libraries/AP_HAL_SITL/Scheduler.cpp

@@ -11,6 +11,7 @@
 #else
 #include <malloc.h>
 #endif
+#include <AP_RCProtocol/AP_RCProtocol.h>
 
 using namespace HALSITL;
 
@@ -209,6 +210,8 @@ void Scheduler::_run_io_procs()
     hal.storage->_timer_tick();
 
     check_thread_stacks();
+
+    AP::RC().update();
 }
 
 /*