SITL: Add RC support for Airsim

Adds variable length float array parsing

libraries/SITL/SIM_AirSim.cpp

@@ -164,6 +164,34 @@ bool AirSim::parse_sensors(const char *json)
                 v->length = n;
                 break;
             }
+
+            case DATA_FLOAT_ARRAY: {
+                // example: [18.0, 12.694079399108887]
+                if (*p++ != '[') {
+                    return false;
+                }
+                uint16_t n = 0;
+                struct float_array *v = (struct float_array *)key.ptr;
+                while (true) {
+                    if (n >= v->length) {
+                        float *d = (float *)realloc(v->data, sizeof(float)*(n+1));
+                        if (d == nullptr) {
+                            return false;
+                        }
+                        v->data = d;
+                        v->length = n+1;
+                    }
+                    v->data[n] = atof(p);
+                    n++;
+                    p = strchr(p,',');
+                    if (!p) {
+                        break;
+                    }
+                    p++;
+                }
+                v->length = n;
+                break;
+            }
         }
     }
     return true;
@@ -234,6 +262,11 @@ void AirSim::recv_fdm()
 
     scanner.points = state.lidar.points;
 
+    rcin_chan_count = state.rc.rc_channels.length < 8 ? state.rc.rc_channels.length : 8;
+    for (uint8_t i=0; i < rcin_chan_count; i++) {
+        rcin[i] = state.rc.rc_channels.data[i];
+    }
+
 #if 0
     AP::logger().Write("ASM1", "TimeUS,TUS,R,P,Y,GX,GY,GZ",
                        "QQffffff",

libraries/SITL/SIM_AirSim.h

@@ -69,6 +69,7 @@ private:
         DATA_DOUBLE,
         DATA_VECTOR3F,
         DATA_VECTOR3F_ARRAY,
+        DATA_FLOAT_ARRAY,
     };
 
     struct {
@@ -89,6 +90,9 @@ private:
         struct {
             struct vector3f_array points;
         } lidar;
+        struct {
+            struct float_array rc_channels;
+        } rc;
     } state, last_state;
 
     // table to aid parsing of JSON sensor data
@@ -97,7 +101,7 @@ private:
         const char *key;
         void *ptr;
         enum data_type type;
-    } keytable[11] = {
+    } keytable[12] = {
         { "", "timestamp", &state.timestamp, DATA_UINT64 },
         { "imu", "angular_velocity",    &state.imu.angular_velocity, DATA_VECTOR3F },
         { "imu", "linear_acceleration", &state.imu.linear_acceleration, DATA_VECTOR3F },
@@ -109,6 +113,7 @@ private:
         { "pose", "yaw",   &state.pose.yaw, DATA_FLOAT },
         { "velocity", "world_linear_velocity", &state.velocity.world_linear_velocity, DATA_VECTOR3F },
         { "lidar", "point_cloud", &state.lidar.points, DATA_VECTOR3F_ARRAY },
+        { "rc", "channels", &state.rc.rc_channels, DATA_FLOAT_ARRAY },
     };
 };