feat(wire): better callback performance

Author: SuGlider

cores/esp32/HardwareI2C.h

@@ -38,6 +38,6 @@ class HardwareI2C : public Stream {
   virtual size_t requestFrom(uint8_t address, size_t len) = 0;
 
   // Update base class to use std::function
-  virtual void onReceive(std::function<void(int)>) = 0;
-  virtual void onRequest(std::function<void()>) = 0;
+  virtual void onReceive(const std::function<void(int)>&) = 0;
+  virtual void onRequest(const std::function<void()>&) = 0;
 };

libraries/Wire/src/Wire.cpp

@@ -596,14 +596,14 @@ void TwoWire::flush() {
   //i2cFlush(num); // cleanup
 }
 
-void TwoWire::onReceive(std::function<void(int)> function) {
+void TwoWire::onReceive(const std::function<void(int)>& function) {
 #if SOC_I2C_SUPPORT_SLAVE
   user_onReceive = function;
 #endif
 }
 
 // sets function called on slave read
-void TwoWire::onRequest(std::function<void()> function) {
+void TwoWire::onRequest(const std::function<void()>& function) {
 #if SOC_I2C_SUPPORT_SLAVE
   user_onRequest = function;
 #endif

libraries/Wire/src/Wire.h

@@ -112,8 +112,8 @@ class TwoWire : public HardwareI2C {
   size_t requestFrom(uint8_t address, size_t len, bool stopBit) override;
   size_t requestFrom(uint8_t address, size_t len) override;
 
-  void onReceive(std::function<void(int)>) override;
-  void onRequest(std::function<void()>) override;
+  void onReceive(const std::function<void(int)>&) override;
+  void onRequest(const std::function<void()>&) override;
 
   //call setPins() first, so that begin() can be called without arguments from libraries
   bool setPins(int sda, int scl);