[Lua] Add setStickySwitch and getLogicalSwitchValue (#1056)

[Lua] Add setStickySwitch and getLogicalSwitchValue (#1056)
* Adds setStickySwitch to set the value of a stick logical switch
* Adds getLogicalSwitchValue to get the value of a logical switch by index

radio/src/lua/api_general.cpp

@@ -1848,6 +1848,62 @@ static int luaGetShmVar(lua_State * L)
 }
 #endif
 
+/*luadoc
+@function setStickySwitch(id, value) 
+
+@param id: integer identifying the sticky logical switch (zero for LS1 etc.).
+
+@param value: true/false. The new value of the sticky logical switch.
+
+@retval bufferFull: true/false. This function sends a message from Lua to the logical switch processor 
+via a buffer with eight slots that are read 10 times per second. If the buffer is full, then a true value 
+is returned and no messages was sent (i.e. the switch was not changed).
+
+Sets the value of a sticky logical switch.
+
+@status current Introduced in 2.6
+*/
+
+#if (MAX_LOGICAL_SWITCHES != 64)
+#warning "The following code assumes that MAX_LOGICAL_SWITCHES == 64!"
+#endif
+
+static int luaSetStickySwitch(lua_State * L)
+{
+  int id = luaL_checkinteger(L, 1);
+  bool value = lua_toboolean(L, 2);
+
+  uint8_t msg = (1 << 6);       // This bit is always set to have a non-zero value
+  if (value) msg |= (1 << 7);
+  msg |= (id & 0x3F);
+
+  lua_pushboolean(L, luaSetStickySwitchBuffer.write(msg));
+  return 1;
+}
+
+/*luadoc
+@function getLogicalSwitchValue(id)
+
+@param id: integer identifying the logical switch (zero for LS1 etc.).
+
+@retval value: true/false.
+
+Reads the value of a logical switch.
+
+@status current Introduced in 2.6
+*/
+
+static int luaGetLogicalSwitchValue(lua_State * L)
+{
+  int id = luaL_checkinteger(L, 1);
+
+  if (id >= 0 && id < MAX_LOGICAL_SWITCHES)
+    lua_pushboolean(L, getSwitch(SWSRC_FIRST_LOGICAL_SWITCH + id));
+  else
+    lua_pushnil(L);
+  return 1;
+}
+
 const luaL_Reg opentxLib[] = {
   { "getTime", luaGetTime },
   { "getDateTime", luaGetDateTime },
@@ -1907,6 +1963,8 @@ const luaL_Reg opentxLib[] = {
   { "setShmVar", luaSetShmVar },
   { "getShmVar", luaGetShmVar },
 #endif
+  { "setStickySwitch", luaSetStickySwitch },
+  { "getLogicalSwitchValue", luaGetLogicalSwitchValue },
   { nullptr, nullptr }  /* sentinel */
 };
 

radio/src/opentx.h

@@ -1310,3 +1310,5 @@ inline bool isAsteriskDisplayed()
 }
 
 #include "module.h"
+
+extern CircularBuffer<uint8_t, 8> luaSetStickySwitchBuffer;

radio/src/opentx_helpers.h

@@ -56,13 +56,49 @@ inline void SWAP(T & a, T & b)
 
 inline void memclear(void * p, size_t size)
 {
-memset(p, 0, size);
+  memset(p, 0, size);
 }
 
 inline bool is_memclear(void * p, size_t size)
 {
-uint8_t * buf = (uint8_t *)p;
-return buf[0] == 0 && memcmp(buf, buf + 1, size - 1) == 0;
+  uint8_t * buf = (uint8_t *)p;
+  return buf[0] == 0 && memcmp(buf, buf + 1, size - 1) == 0;
 }
 
+// Circular buffer to send data between two threads
+template<class T, uint8_t N>
+class CircularBuffer {
+  protected:
+    volatile T buffer[N] = {0};
+    uint8_t readPos = 0;
+    uint8_t writePos = 0;
+    
+  public:
+    void clear()
+    {
+      memclear(this, sizeof(*this));
+    }
+
+    T read()
+    {
+      T value = buffer[readPos];
+      if (value) {
+        buffer[readPos] = 0;
+        readPos = (readPos + 1) % N;
+      }
+      return value;
+    }
+
+    // Values must be non-zero
+    bool write(T value)
+    {
+      if (value && !buffer[writePos]) {
+        buffer[writePos] = value;
+        writePos = (writePos + 1) % N;
+        return false;
+      }    
+      return true;
+    }  
+};
+
 #endif

radio/src/switches.cpp

@@ -53,6 +53,7 @@ PACK(struct LogicalSwitchesFlightModeContext {
   LogicalSwitchContext lsw[MAX_LOGICAL_SWITCHES];
 });
 LogicalSwitchesFlightModeContext lswFm[MAX_FLIGHT_MODES];
+CircularBuffer<uint8_t, 8> luaSetStickySwitchBuffer;
 
 #define LS_LAST_VALUE(fm, idx) lswFm[fm].lsw[idx].lastValue
 
@@ -789,6 +790,34 @@ void checkSwitches()
 
 void logicalSwitchesTimerTick()
 {
+#if (MAX_LOGICAL_SWITCHES != 64)
+#warning "The following code assumes that MAX_LOGICAL_SWITCHES == 64!"
+#endif
+  // Read messages from Lua in the buffer and flick switches
+  uint8_t msg = luaSetStickySwitchBuffer.read();
+  while(msg) {
+    uint8_t i = msg & 0x3F;
+    uint8_t s = msg >> 7;
+    LogicalSwitchData * ls = lswAddress(i);
+    if (ls->func == LS_FUNC_STICKY) {
+      for (uint8_t fm=0; fm<MAX_FLIGHT_MODES; fm++) {
+        ls_sticky_struct & lastValue = (ls_sticky_struct &)LS_LAST_VALUE(fm, i);
+        lastValue.state = s;
+        bool now;
+        if (s)
+          now = getSwitch(ls->v2);
+        else
+          now = getSwitch(ls->v1);
+        if (now)
+          lastValue.last |= 1;
+        else
+          lastValue.last &= ~1;
+      }
+    }
+    msg = luaSetStickySwitchBuffer.read();
+  }
+  
+  // Update logical switches
   for (uint8_t fm=0; fm<MAX_FLIGHT_MODES; fm++) {
     for (uint8_t i=0; i<MAX_LOGICAL_SWITCHES; i++) {
       LogicalSwitchData * ls = lswAddress(i);
@@ -900,6 +929,8 @@ void logicalSwitchesReset()
       LS_LAST_VALUE(fm, i) = CS_LAST_VALUE_INIT;
     }
   }
+  
+  luaSetStickySwitchBuffer.clear();
 }
 
 getvalue_t convertLswTelemValue(LogicalSwitchData * ls)