Copter: simplify auxsw duplicates check

ArduCopter/defines.h

@@ -69,6 +69,7 @@ enum aux_sw_func {
     AUXSW_RELAY4 =              36, // Relay4 pin on/off (in Mission planner set CH10_OPT = 36)
     AUXSW_THROW =               37,  // change to THROW flight mode
     AUXSW_AVOID_ADSB =          38,  // enable AP_Avoidance library
+    AUXSW_SWITCH_MAX,
 };
 
 // Frame types

ArduCopter/switches.cpp

@@ -86,23 +86,23 @@ bool Copter::check_if_auxsw_mode_used(uint8_t auxsw_mode_check)
 // check_duplicate_auxsw - Check to see if any Aux Switch Functions are duplicated
 bool Copter::check_duplicate_auxsw(void)
 {
-    bool ret = ((g.ch7_option != AUXSW_DO_NOTHING) && (g.ch7_option == g.ch8_option ||
+    uint8_t auxsw_option_counts[AUXSW_SWITCH_MAX] = {};
-                g.ch7_option == g.ch9_option || g.ch7_option == g.ch10_option ||
+    auxsw_option_counts[g.ch7_option]++;
-                g.ch7_option == g.ch11_option || g.ch7_option == g.ch12_option));
+    auxsw_option_counts[g.ch8_option]++;
+    auxsw_option_counts[g.ch9_option]++;
+    auxsw_option_counts[g.ch10_option]++;
+    auxsw_option_counts[g.ch11_option]++;
+    auxsw_option_counts[g.ch12_option]++;
 
-    ret = ret || ((g.ch8_option != AUXSW_DO_NOTHING) && (g.ch8_option == g.ch9_option ||
+    for (uint8_t i=0; i<sizeof(auxsw_option_counts); i++) {
-                    g.ch8_option == g.ch10_option || g.ch8_option == g.ch11_option ||
+        if (i == AUXSW_DO_NOTHING) {
-                    g.ch8_option == g.ch12_option));
+            continue;
-
+        }
-    ret = ret || ((g.ch9_option != AUXSW_DO_NOTHING) && (g.ch9_option == g.ch10_option ||
+        if (auxsw_option_counts[i] > 1) {
-                    g.ch9_option == g.ch11_option || g.ch9_option == g.ch12_option));
+            return true;
-
+        }
-    ret = ret || ((g.ch10_option != AUXSW_DO_NOTHING) && (g.ch10_option == g.ch11_option ||
+    }
-                    g.ch10_option == g.ch12_option));
+   return false;
-
-    ret = ret || ((g.ch11_option != AUXSW_DO_NOTHING) && (g.ch11_option == g.ch12_option));
-
-    return ret;
 }
 
 void Copter::reset_control_switch()