Add locks

RCSwitch.cpp

@@ -33,6 +33,7 @@
 */
 
 #include "RCSwitch.h"
+#include <assert.h>
 
 #ifdef RaspberryPi
     // PROGMEM and _P functions are for AVR based microprocessors,
@@ -103,7 +104,13 @@ const unsigned int RCSwitch::nSeparationLimit = 4300;
 // according to discussion on issue #14 it might be more suitable to set the separation
 // limit to the same time as the 'low' part of the sync signal for the current protocol.
 unsigned int RCSwitch::timings[RCSWITCH_MAX_CHANGES];
-#endif
+#if defined(WITH_LOCKS)
+volatile bool RCSwitch::useLocks = false;
+std::mutex RCSwitch::mutex;
+std::condition_variable RCSwitch::receiveGuard;
+#endif // WITH_LOCKS
+
+#endif // !RCSwitchDisableReceiving
 
 RCSwitch::RCSwitch() {
   this->nTransmitterPin = -1;
@@ -601,6 +608,22 @@ static inline unsigned int diff(int A, int B) {
   return abs(A - B);
 }
 
+#if defined(WITH_LOCKS)
+void RCSwitch::enableLocks() {
+    this->useLocks = true;
+}
+void RCSwitch::wait() {
+    assert(useLocks);
+    if (!useLocks) {
+        return;
+    }
+    while (!available()) {
+        std::unique_lock<std::mutex> lock(this->mutex);
+        receiveGuard.wait(lock);
+    }
+}
+#endif
+
 /**
  *
  */
@@ -653,10 +676,22 @@ bool RECEIVE_ATTR RCSwitch::receiveProtocol(const int p, unsigned int changeCoun
     }
 
     if (changeCount > 7) {    // ignore very short transmissions: no device sends them, so this must be noise
+        #if defined(WITH_LOCKS)    
+        std::unique_lock<std::mutex> lock(mutex, std::defer_lock);
+        if (useLocks) {
+            lock.lock();
+        }
+        #endif
+        // The following code is lock-guarded when using locks.
         RCSwitch::nReceivedValue = code;
         RCSwitch::nReceivedBitlength = (changeCount - 1) / 2;
         RCSwitch::nReceivedDelay = delay;
         RCSwitch::nReceivedProtocol = p;
+        #if defined(WITH_LOCKS)
+        if (useLocks) {
+            receiveGuard.notify_all();
+        }
+        #endif
         return true;
     }
 

RCSwitch.h

@@ -47,6 +47,15 @@
     #include "WProgram.h"
 #endif
 
+#if defined(WITH_LOCKS) && !defined(RaspberryPi)
+    #error "Locks are not supported outside Raspberry Pi!"
+#endif
+
+#if defined(WITH_LOCKS)
+    #include <condition_variable>
+    #include <mutex>
+#endif
+
 #include <stdint.h>
 
 
@@ -148,6 +157,14 @@ class RCSwitch {
     void setProtocol(int nProtocol);
     void setProtocol(int nProtocol, int nPulseLength);
 
+    #if defined(WITH_LOCKS)
+    // Enabled the handling of locks. 
+    // If enabled, the caller can use the wait() function to wait for data.
+    void enableLocks();
+    void wait();
+    #endif
+
+
   private:
     char* getCodeWordA(const char* sGroup, const char* sDevice, bool bStatus);
     char* getCodeWordB(int nGroupNumber, int nSwitchNumber, bool bStatus);
@@ -160,6 +177,13 @@ class RCSwitch {
     static bool receiveProtocol(const int p, unsigned int changeCount);
     int nReceiverInterrupt;
     #endif
+
+    #if defined(WITH_LOCKS) 
+    static std::mutex mutex;
+    static std::condition_variable receiveGuard;
+    static volatile bool useLocks;
+    #endif
+
     int nTransmitterPin;
     int nRepeatTransmit;