fix(radio): Better iteration through mixers on display, sanitize invalid sources (#3999)

* fix: mixer lines with empty source

Fixes #3367

* Fix color mixes display.

---------

Co-authored-by: Phil Mitchell <phil.a.mitchell@gmail.com>

radio/src/CMakeLists.txt

@@ -388,6 +388,7 @@ set(SRC
   strhelpers.cpp
   switches.cpp
   analogs.cpp
+  mixes.cpp
   mixer.cpp
   mixer_scheduler.cpp
   stamp.cpp

radio/src/gui/128x64/gui.h

@@ -158,9 +158,6 @@ extern uint8_t editNameCursorPos;
 uint8_t getExposCount();
 void insertExpo(uint8_t idx);
 void deleteExpo(uint8_t idx);
-uint8_t getMixesCount();
-void insertMix(uint8_t idx);
-void deleteMix(uint8_t idx);
 
 void onSwitchLongEnterPress(const char *result);
 void onSourceLongEnterPress(const char *result);

radio/src/gui/128x64/model_mix_edit.cpp

@@ -20,6 +20,7 @@
  */
 
 #include "opentx.h"
+#include "mixes.h"
 
 enum MixFields {
   MIX_FIELD_NAME,

radio/src/gui/212x64/gui.h

@@ -157,10 +157,6 @@ uint8_t getExposCount();
 void deleteExpo(uint8_t idx);
 void insertExpo(uint8_t idx);
 
-uint8_t getMixesCount();
-void deleteMix(uint8_t idx);
-void insertMix(uint8_t idx);
-
 #define STATUS_LINE_LENGTH             32
 extern char statusLineMsg[STATUS_LINE_LENGTH];
 void showStatusLine();

radio/src/gui/212x64/model_mix_edit.cpp

@@ -20,6 +20,7 @@
  */
 
 #include "opentx.h"
+#include "mixes.h"
 
 enum MixFields {
   MIX_FIELD_NAME,

radio/src/gui/colorlcd/menus.h

@@ -101,11 +101,6 @@ uint8_t getExposCount();
 void deleteExpo(uint8_t idx);
 void insertExpo(uint8_t idx, uint8_t input);
 
-uint8_t getMixesCount();
-void deleteMix(uint8_t idx);
-void insertMix(uint8_t idx);
-void copyMix(uint8_t source, uint8_t dest, int8_t ch);
-
 typedef int (*FnFuncP) (int x);
 void drawFunction(FnFuncP fn, int x, int y, int width);
 

radio/src/gui/colorlcd/mixer_edit.cpp

@@ -24,6 +24,7 @@
 #include "channel_bar.h"
 #include "gvar_numberedit.h"
 #include "curve_param.h"
+#include "mixes.h"
 
 #include "opentx.h"
 

radio/src/gui/colorlcd/mixer_edit_adv.cpp

@@ -22,6 +22,7 @@
 #include "mixer_edit_adv.h"
 #include "numberedit.h"
 #include "fm_matrix.h"
+#include "mixes.h"
 
 #include "opentx.h"
 

radio/src/gui/colorlcd/model_mixes.cpp

@@ -31,6 +31,7 @@
 #include "input_mix_button.h"
 #include "mixer_edit.h"
 #include "input_mapping.h"
+#include "mixes.h"
 
 #include "tasks/mixer_task.h"
 #include "hal/adc_driver.h"
@@ -54,119 +55,6 @@ static const uint8_t _mask_mplex_replace[] = {
 };
 STATIC_LZ4_BITMAP(mask_mplex_replace);
 
-uint8_t getMixesCount()
-{
-  uint8_t count = 0;
-  uint8_t ch;
-
-  for (int i = MAX_MIXERS - 1; i >= 0; i--) {
-    ch = mixAddress(i)->srcRaw;
-    if (ch != 0) {
-      count++;
-    }
-  }
-  return count;
-}
-
-void insertMix(uint8_t idx, uint8_t channel)
-{
-  mixerTaskStop();
-  MixData *mix = mixAddress(idx);
-  memmove(mix + 1, mix, (MAX_MIXERS - (idx + 1)) * sizeof(MixData));
-  memclear(mix, sizeof(MixData));
-  mix->destCh = channel;
-  mix->srcRaw = channel + 1;
-  if (!isSourceAvailable(mix->srcRaw)) {
-    if (channel >= adcGetMaxInputs(ADC_INPUT_MAIN)) {
-      mix->srcRaw = MIXSRC_FIRST_STICK + channel;
-    } else {
-      mix->srcRaw = MIXSRC_FIRST_STICK + inputMappingChannelOrder(channel);
-    }
-    while (!isSourceAvailable(mix->srcRaw)) {
-      mix->srcRaw += 1;
-    }
-  }
-  mix->weight = 100;
-  mixerTaskStart();
-  storageDirty(EE_MODEL);
-}
-
-void deleteMix(uint8_t idx)
-{
-  mixerTaskStop();
-  MixData * mix = mixAddress(idx);
-  memmove(mix, mix + 1, (MAX_MIXERS - (idx + 1)) * sizeof(MixData));
-  memclear(&g_model.mixData[MAX_MIXERS - 1], sizeof(MixData));
-  mixerTaskStart();
-  storageDirty(EE_MODEL);
-}
-
-#if defined(LUA)
-// This is necessary as the LUA API uses th old interface
-// where insertMix() has only one param. The channel is
-// passed through s_currCh
-void insertMix(uint8_t idx)
-{
-  insertMix(idx, s_currCh - 1);
-}
-#endif
-
-void copyMix(uint8_t source, uint8_t dest, int8_t ch)
-{
-  mixerTaskStop();
-  MixData sourceMix;
-  memcpy(&sourceMix, mixAddress(source), sizeof(MixData));
-  MixData *mix = mixAddress(dest);
-  size_t trailingMixes = MAX_MIXERS - (dest + 1);
-  memmove(mix + 1, mix, trailingMixes * sizeof(MixData));
-  memcpy(mix, &sourceMix, sizeof(MixData));
-  mix->destCh = ch;
-  mixerTaskStart();
-  storageDirty(EE_MODEL);
-}
-
-bool swapMixes(uint8_t &idx, uint8_t up)
-{
-  MixData * x, * y;
-  int8_t tgt_idx = (up ? idx - 1 : idx + 1);
-
-  x = mixAddress(idx);
-
-  if (tgt_idx < 0) {
-    if (x->destCh == 0)
-      return false;
-    x->destCh--;
-    return true;
-  }
-
-  if (tgt_idx == MAX_MIXERS) {
-    if (x->destCh == MAX_OUTPUT_CHANNELS - 1)
-      return false;
-    x->destCh++;
-    return true;
-  }
-
-  y = mixAddress(tgt_idx);
-  uint8_t destCh = x->destCh;
-  if (!y->srcRaw || destCh != y->destCh) {
-    if (up) {
-      if (destCh > 0) x->destCh--;
-      else return false;
-    }
-    else {
-      if (destCh < MAX_OUTPUT_CHANNELS - 1) x->destCh++;
-      else return false;
-    }
-    return true;
-  }
-
-  mixerTaskStop();
-  memswap(x, y, sizeof(MixData));
-  mixerTaskStart();
-
-  idx = tgt_idx;
-  return true;
-}
 
 class MixLineButton : public InputMixButton
 {
@@ -312,7 +200,7 @@ ModelMixesPage::ModelMixesPage() :
 
 bool ModelMixesPage::reachMixesLimit()
 {
-  if (getMixesCount() >= MAX_MIXERS) {
+  if (getMixCount() >= MAX_MIXERS) {
     new MessageDialog(form, STR_WARNING, STR_NOFREEMIXER);
     return true;
   }
@@ -550,17 +438,14 @@ void ModelMixesPage::build(FormWindow * window)
   bool focusSet = false;
   uint8_t index = 0;
   MixData* line = g_model.mixData;
-  for (uint8_t ch = 0; ch < MAX_OUTPUT_CHANNELS; ch++) {
+  for (uint8_t ch = 0; (ch < MAX_OUTPUT_CHANNELS) && (index < MAX_MIXERS); ch++) {
 
-    if (index >= MAX_MIXERS) break;
-
-    bool skip_mix = (ch == 0 && is_memclear(line, sizeof(MixData)));
-    if (line->destCh == ch && !skip_mix) {
+    if (line->destCh == ch) {
 
       // one group for the complete mixer channel
       auto group = createGroup(form, MIXSRC_FIRST_CH + ch);
       groups.emplace_back(group);
-      while (index < MAX_MIXERS && (line->destCh == ch) && !skip_mix) {
+      while (index < MAX_MIXERS && (line->destCh == ch)) {
         // one button per input line
         auto btn = createLineButton(group, index);
         if (!focusSet) {
@@ -569,7 +454,6 @@ void ModelMixesPage::build(FormWindow * window)
         }
         ++index;
         ++line;
-        skip_mix = (ch == 0 && is_memclear(line, sizeof(MixData)));
       }
     }
   }

radio/src/gui/common/stdlcd/model_mixes.cpp

@@ -23,118 +23,20 @@
 #include "tasks/mixer_task.h"
 #include "hal/adc_driver.h"
 #include "input_mapping.h"
+#include "mixes.h"
 
 #define _STR_MAX(x)                     "/" #x
 #define STR_MAX(x)                     _STR_MAX(x)
 
-uint8_t getMixesCount()
-{
-  uint8_t count = 0;
-  uint8_t ch;
-
-  for (int i=MAX_MIXERS-1; i>=0; i--) {
-    ch = mixAddress(i)->srcRaw;
-    if (ch != 0) {
-      count++;
-    }
-  }
-  return count;
-}
-
 bool reachMixesLimit()
 {
-  if (getMixesCount() >= MAX_MIXERS) {
+  if (getMixCount() >= MAX_MIXERS) {
     POPUP_WARNING(STR_NOFREEMIXER);
     return true;
   }
   return false;
 }
 
-void deleteMix(uint8_t idx)
-{
-  mixerTaskStop();
-  MixData * mix = mixAddress(idx);
-  memmove(mix, mix+1, (MAX_MIXERS-(idx+1))*sizeof(MixData));
-  memclear(&g_model.mixData[MAX_MIXERS-1], sizeof(MixData));
-  mixerTaskStart();
-  storageDirty(EE_MODEL);
-}
-
-void insertMix(uint8_t idx)
-{
-  mixerTaskStop();
-  MixData * mix = mixAddress(idx);
-  memmove(mix+1, mix, (MAX_MIXERS-(idx+1))*sizeof(MixData));
-  memclear(mix, sizeof(MixData));
-  mix->destCh = s_currCh-1;
-  mix->srcRaw = s_currCh;
-  if (!isSourceAvailable(mix->srcRaw)) {
-    if (s_currCh > adcGetMaxInputs(ADC_INPUT_MAIN)) {
-      mix->srcRaw = MIXSRC_FIRST_STICK - 1 + s_currCh;
-    } else {
-      mix->srcRaw = MIXSRC_FIRST_STICK + inputMappingChannelOrder(s_currCh - 1);
-    }
-    while (!isSourceAvailable(mix->srcRaw)) {
-      mix->srcRaw += 1;
-    }
-  }
-  mix->weight = 100;
-  mixerTaskStart();
-  storageDirty(EE_MODEL);
-}
-
-void copyMix(uint8_t idx)
-{
-  mixerTaskStop();
-  MixData * mix = mixAddress(idx);
-  memmove(mix+1, mix, (MAX_MIXERS-(idx+1))*sizeof(MixData));
-  mixerTaskStart();
-  storageDirty(EE_MODEL);
-}
-
-bool swapMixes(uint8_t & idx, uint8_t up)
-{
-  MixData * x, * y;
-  int8_t tgt_idx = (up ? idx-1 : idx+1);
-
-  x = mixAddress(idx);
-
-  if (tgt_idx < 0) {
-    if (x->destCh == 0)
-      return false;
-    x->destCh--;
-    return true;
-  }
-
-  if (tgt_idx == MAX_MIXERS) {
-    if (x->destCh == MAX_OUTPUT_CHANNELS-1)
-      return false;
-    x->destCh++;
-    return true;
-  }
-
-  y = mixAddress(tgt_idx);
-  uint8_t destCh = x->destCh;
-  if(!y->srcRaw || destCh != y->destCh) {
-    if (up) {
-      if (destCh>0) x->destCh--;
-      else return false;
-    }
-    else {
-      if (destCh<MAX_OUTPUT_CHANNELS-1) x->destCh++;
-      else return false;
-    }
-    return true;
-  }
-
-  mixerTaskStop();
-  memswap(x, y, sizeof(MixData));
-  mixerTaskStart();
-
-  idx = tgt_idx;
-  return true;
-}
-
 void onMixesMenu(const char * result)
 {
   uint8_t chn = mixAddress(s_currIdx)->destCh + 1;
@@ -146,7 +48,7 @@ void onMixesMenu(const char * result)
     if (!reachMixesLimit()) {
       s_currCh = chn;
       if (result == STR_INSERT_AFTER) { s_currIdx++; menuVerticalPosition++; }
-      insertMix(s_currIdx);
+      insertMix(s_currIdx, s_currCh - 1);
       pushMenu(menuModelMixOne);
     }
   }
@@ -289,7 +191,7 @@ void menuModelMixAll(event_t event)
           }
           else {
             do {
-              swapMixes(s_currIdx, s_copyTgtOfs > 0);
+              s_currIdx = moveMix(s_currIdx, s_copyTgtOfs > 0);
               s_copyTgtOfs += (s_copyTgtOfs < 0 ? +1 : -1);
             } while (s_copyTgtOfs != 0);
             storageDirty(EE_MODEL);
@@ -327,7 +229,7 @@ void menuModelMixAll(event_t event)
           if (s_copyMode) s_currCh = 0;
           if (s_currCh) {
             if (reachMixesLimit()) break;
-            insertMix(s_currIdx);
+            insertMix(s_currIdx, s_currCh - 1);
             pushMenu(menuModelMixOne);
             s_copyMode = 0;
           }
@@ -353,7 +255,7 @@ void menuModelMixAll(event_t event)
     //     if (reachMixesLimit()) break;
     //     s_currCh = chn;
     //     if (event == EVT_KEY_LONG(KEY_RIGHT)) { s_currIdx++; menuVerticalPosition++; }
-    //     insertMix(s_currIdx);
+    //     insertMix(s_currIdx, s_currCh - 1);
     //     pushMenu(menuModelMixOne);
     //     s_copyMode = 0;
     //     killEvents(event);
@@ -369,7 +271,7 @@ void menuModelMixAll(event_t event)
     if (s_copyTgtOfs==0 && s_copyMode==COPY_MODE) {
       // insert a mix on the same channel (just above / just below)
       if (!reachMixesLimit()) {
-        copyMix(s_currIdx);
+        copyMix(s_currIdx, s_currIdx, mixAddress(s_currIdx)->destCh);
         if (IS_NEXT_EVENT(event))
           s_currIdx++;
         else if (sub - menuVerticalOffset >= 6)
@@ -384,15 +286,13 @@ void menuModelMixAll(event_t event)
     }
     else {
       // only swap the mix with its neighbor
-      if (swapMixes(s_currIdx, IS_PREVIOUS_EVENT(event))) {
-        storageDirty(EE_MODEL);
-      }
+      moveMix(s_currIdx, IS_PREVIOUS_EVENT(event));
     }
 
     s_copyTgtOfs = next_ofs;
   }
 
-  lcdDrawNumber(FW*sizeof(TR_MIXES)+FW/2, 0, getMixesCount(), 0);
+  lcdDrawNumber(FW*sizeof(TR_MIXES)+FW/2, 0, getMixCount(), 0);
   lcdDrawText(lcdNextPos, 0, STR_MAX(MAX_MIXERS));
 
   // Value
@@ -419,9 +319,9 @@ void menuModelMixAll(event_t event)
   int i = 0;
 
   for (uint8_t ch=1; ch<=MAX_OUTPUT_CHANNELS; ch++) {
-    MixData * md;
     coord_t y = MENU_HEADER_HEIGHT+1+(cur-menuVerticalOffset)*FH;
-    if (i<MAX_MIXERS && (md=mixAddress(i))->srcRaw && md->destCh+1 == ch) {
+    MixData * md = mixAddress(i);
+    if (i < getMixCount() && (md->destCh + 1 == ch)) {
       if (cur-menuVerticalOffset >= 0 && cur-menuVerticalOffset < NUM_BODY_LINES) {
         putsChn(0, y, ch, 0); // show CHx
       }
@@ -473,7 +373,7 @@ void menuModelMixAll(event_t event)
           }
         }
         cur++; y+=FH; mixCnt++; i++; md++;
-      } while (i<MAX_MIXERS && md->srcRaw && md->destCh+1 == ch);
+      } while (i < getMixCount() && (md->destCh + 1 == ch));
       if (s_copyMode == MOVE_MODE && cur-menuVerticalOffset >= 0 && cur-menuVerticalOffset < NUM_BODY_LINES && s_copySrcCh == ch && i == (s_copySrcIdx + (s_copyTgtOfs<0))) {
         lcdDrawRect(22, y-1, LCD_W-22, 9, DOTTED);
         cur++;

radio/src/gui/gui_common.cpp

@@ -25,6 +25,7 @@
 #include "hal/adc_driver.h"
 #include "hal/switch_driver.h"
 #include "switches.h"
+#include "mixes.h"
 
 #undef CPN
 #include "MultiSubtypeDefs.h"

radio/src/lua/api_model.cpp

@@ -28,6 +28,7 @@
 #include "../timers.h"
 #include "model_init.h"
 #include "gvars.h"
+#include "mixes.h"
 
 #if defined(SDCARD_YAML)
 #include <storage/sdcard_yaml.h>
@@ -887,10 +888,9 @@ static int luaModelInsertMix(lua_State *L)
   unsigned int first = getFirstMix(chn);
   unsigned int count = getMixesCountFromFirst(chn, first);
 
-  if (chn<MAX_OUTPUT_CHANNELS && getMixesCount()<MAX_MIXERS && idx<=count) {
+  if (chn<MAX_OUTPUT_CHANNELS && getMixCount()<MAX_MIXERS && idx<=count) {
     idx += first;
-    s_currCh = chn+1;
-    insertMix(idx);
+    insertMix(idx, chn + 1);
     MixData *mix = mixAddress(idx);
     luaL_checktype(L, -1, LUA_TTABLE);
     for (lua_pushnil(L); lua_next(L, -2); lua_pop(L, 1)) {

radio/src/mixer.cpp

@@ -23,6 +23,7 @@
 #include "timers.h"
 #include "switches.h"
 #include "input_mapping.h"
+#include "mixes.h"
 
 #include "hal/adc_driver.h"
 #include "hal/trainer_driver.h"

radio/src/mixes.cpp

@@ -0,0 +1,159 @@
+/*
+ * Copyright (C) EdgeTX
+ *
+ * Based on code named
+ *   opentx - https://github.com/opentx/opentx
+ *   th9x - http://code.google.com/p/th9x
+ *   er9x - http://code.google.com/p/er9x
+ *   gruvin9x - http://code.google.com/p/gruvin9x
+ *
+ * License GPLv2: http://www.gnu.org/licenses/gpl-2.0.html
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include "mixes.h"
+#include "tasks/mixer_task.h"
+#include "hal/adc_driver.h"
+
+#include "opentx.h"
+
+static uint8_t _nb_mix_lines;
+
+MixData* mixAddress(uint8_t idx) { return &g_model.mixData[idx]; }
+
+uint8_t getMixCount() { return _nb_mix_lines; }
+
+void insertMix(uint8_t idx, uint8_t channel)
+{
+  mixerTaskStop();
+  MixData * mix = mixAddress(idx);
+  memmove(mix + 1, mix, (MAX_MIXERS - (idx + 1)) * sizeof(MixData));
+  memclear(mix, sizeof(MixData));
+  mix->destCh = channel;
+  mix->srcRaw = channel + 1;
+  if (!isSourceAvailable(mix->srcRaw)) {
+    if (s_currCh > adcGetMaxInputs(ADC_INPUT_MAIN)) {
+      mix->srcRaw = MIXSRC_FIRST_STICK + channel;
+    } else {
+      mix->srcRaw = MIXSRC_FIRST_STICK + inputMappingChannelOrder(channel);
+    }
+    while (!isSourceAvailable(mix->srcRaw)) {
+      mix->srcRaw += 1;
+    }
+  }
+  mix->weight = 100;
+  mixerTaskStart();
+
+  _nb_mix_lines += 1;
+  storageDirty(EE_MODEL);
+}
+
+void deleteMix(uint8_t idx)
+{
+  mixerTaskStop();
+  MixData * mix = mixAddress(idx);
+  memmove(mix, mix + 1, (MAX_MIXERS - (idx + 1)) * sizeof(MixData));
+  memclear(&g_model.mixData[MAX_MIXERS - 1], sizeof(MixData));
+  mixerTaskStart();
+
+  _nb_mix_lines -= 1;
+  storageDirty(EE_MODEL);
+}
+
+void copyMix(uint8_t src, uint8_t dst, uint8_t channel)
+{
+  mixerTaskStop();
+  MixData sourceMix;
+  memcpy(&sourceMix, mixAddress(src), sizeof(MixData));
+  MixData* mix = mixAddress(dst);
+  size_t trailingMixes = MAX_MIXERS - (dst + 1);
+  memmove(mix + 1, mix, trailingMixes * sizeof(MixData));
+  memcpy(mix, &sourceMix, sizeof(MixData));
+  mix->destCh = channel;
+  mixerTaskStart();
+
+  _nb_mix_lines += 1;
+  storageDirty(EE_MODEL);
+}
+
+// Move the mixer line at 'idx' up or down
+// by one position and return the new index.
+uint8_t moveMix(uint8_t idx, bool up)
+{
+  MixData * x, * y;
+  int8_t tgt_idx = (up ? idx-1 : idx+1);
+
+  x = mixAddress(idx);
+
+  if (tgt_idx < 0) {
+    if (x->destCh > 0) {
+      x->destCh--;
+      storageDirty(EE_MODEL);
+    }
+    return idx;
+  }
+
+  if (tgt_idx == MAX_MIXERS) {
+    if (x->destCh < MAX_OUTPUT_CHANNELS - 1) {
+      x->destCh++;
+      storageDirty(EE_MODEL);
+    }
+    return idx;
+  }
+
+  y = mixAddress(tgt_idx);
+  uint8_t destCh = x->destCh;
+
+  // If current target is empty or
+  // assigned to a different channel:
+  //
+  // TODO: check what happens with the mixer
+  //       when channel is changed on-the-fly
+  //
+  if(!y->srcRaw || destCh != y->destCh) {
+    if (up) {
+      if (destCh > 0) {
+	x->destCh--;
+	storageDirty(EE_MODEL);
+      }
+    }
+    else {
+      if (destCh < MAX_OUTPUT_CHANNELS - 1) {
+	x->destCh++;
+	storageDirty(EE_MODEL);
+      }
+    }
+    return idx;
+  }
+
+  mixerTaskStop();
+  memswap(x, y, sizeof(MixData));
+  mixerTaskStart();
+
+  storageDirty(EE_MODEL);
+  return tgt_idx;
+}
+
+static uint8_t _countMixLines()
+{
+  // search for first blank
+  uint8_t i = 0;
+  do {
+    if (is_memclear(mixAddress(i), sizeof(MixData))) break;
+  } while (++i < MAX_MIXERS);
+
+  return i;
+}
+
+void updateMixCount()
+{
+  _nb_mix_lines = _countMixLines();
+}

radio/src/mixes.h

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) EdgeTX
+ *
+ * Based on code named
+ *   opentx - https://github.com/opentx/opentx
+ *   th9x - http://code.google.com/p/th9x
+ *   er9x - http://code.google.com/p/er9x
+ *   gruvin9x - http://code.google.com/p/gruvin9x
+ *
+ * License GPLv2: http://www.gnu.org/licenses/gpl-2.0.html
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+struct MixData;
+
+// Get a pointer to a mixer line
+MixData* mixAddress(uint8_t idx);
+
+// Insert a new mixer line at 'idx'
+void insertMix(uint8_t idx, uint8_t channel);
+
+// Delete mixer line at 'idx'
+void deleteMix(uint8_t idx);
+
+// Duplicate mixer line at 'idx' in place
+void copyMix(uint8_t idx, uint8_t dst, uint8_t channel);
+
+// Move the mixer line at 'idx' up or down
+// by one position and return the new index.
+uint8_t moveMix(uint8_t idx, bool up);
+
+uint8_t getMixCount();
+
+// Should only be called from storage
+// right after a model has been loaded
+void updateMixCount();

radio/src/model_init.cpp

@@ -22,6 +22,7 @@
 #include "opentx.h"
 #include "hal/adc_driver.h"
 #include "input_mapping.h"
+#include "mixes.h"
 
 void clearInputs()
 {

radio/src/opentx.cpp

@@ -215,11 +215,6 @@ ExpoData *expoAddress(uint8_t idx )
   return &g_model.expoData[idx];
 }
 
-MixData *mixAddress(uint8_t idx)
-{
-  return &g_model.mixData[idx];
-}
-
 LimitData *limitAddress(uint8_t idx)
 {
   return &g_model.limitData[idx];

radio/src/opentx.h

@@ -627,7 +627,6 @@ uint16_t anaIn(uint8_t chan);
 
 FlightModeData * flightModeAddress(uint8_t idx);
 ExpoData * expoAddress(uint8_t idx);
-MixData * mixAddress(uint8_t idx);
 LimitData * limitAddress(uint8_t idx);
 LogicalSwitchData * lswAddress(uint8_t idx);
 USBJoystickChData * usbJChAddress(uint8_t idx);

radio/src/storage/storage_common.cpp

@@ -22,6 +22,7 @@
 #include "opentx.h"
 #include "timers_driver.h"
 #include "tasks/mixer_task.h"
+#include "mixes.h"
 
 #if defined(USBJ_EX)
 #include "usb_joystick.h"
@@ -106,7 +107,7 @@ void postRadioSettingsLoad()
 #endif
 }
 
-static void sortMixerLines()
+static bool sortMixerLines()
 {
   // simple bubble sort
   unsigned passes = 0;
@@ -132,9 +133,16 @@ static void sortMixerLines()
     ++passes;
   } while(swaps > 0);
 
-  if (passes > 1) {
-    storageDirty(EE_MODEL);
-  }
+  // anything above 1 means that
+  // we changed something
+  return passes > 1;
+}
+
+static void sanitizeMixerLines()
+{
+  bool dirty = sortMixerLines();
+  updateMixCount();
+  if (dirty) storageDirty(EE_MODEL);
 }
 
 void postModelLoad(bool alarms)
@@ -226,7 +234,7 @@ if(g_model.rssiSource) {
   }
 
   loadCurves();
-  sortMixerLines();
+  sanitizeMixerLines();
 
 #if defined(GUI)
   if (alarms) {