Remove use of slave_bytesToWrite and slave_writeData in Wire.cpp

Author: sandeepmistry

libraries/Wire/src/Wire.cpp

@@ -75,7 +75,7 @@ void TwoWire::begin(uint8_t address)
 
 	TWI_SlaveInit(address);
 
-	TWI_attachSlaveTxEvent(onRequestService); // default callback must exist
+	TWI_attachSlaveTxEvent(onRequestService, txBuffer); // default callback must exist
 	TWI_attachSlaveRxEvent(onReceiveService, rxBuffer, BUFFER_LENGTH); // default callback must exist
 
 }
@@ -291,11 +291,11 @@ void TwoWire::onReceiveService(int numBytes)
 }
 
 // behind the scenes function that is called when data is requested
-void TwoWire::onRequestService(void)
+uint8_t TwoWire::onRequestService(void)
 {
 	// don't bother if user hasn't registered a callback
 	if(!user_onRequest){
-		return;
+		return 0;
 	}
 
 	// reset slave write buffer iterator var
@@ -305,8 +305,7 @@ void TwoWire::onRequestService(void)
 	// alert user program
 	user_onRequest();
 
-	slave_bytesToWrite = txBufferLength;
-	slave_writeData = txBuffer;
+	return txBufferLength;
 }
 
 // sets function called on slave write

libraries/Wire/src/Wire.h

@@ -44,7 +44,7 @@ class TwoWire : public HardwareI2C
     static uint8_t transmitting;
     static void (*user_onRequest)(void);
     static void (*user_onReceive)(int);
-    static void onRequestService(void);
+    static uint8_t onRequestService(void);
     static void onReceiveService(int);
   public:
     TwoWire();

libraries/Wire/src/utility/twi.c

@@ -577,7 +577,7 @@ void TWI_SlaveAddressMatchHandler(){
 	if(TWI0.SSTATUS & TWI_DIR_bm){
 		slave_bytesWritten = 0;
 		/* Call user function  */
-		TWI_onSlaveTransmit();	
+		slave_bytesToWrite = TWI_onSlaveTransmit();	
 		twi_mode = TWI_MODE_SLAVE_TRANSMIT;
 	} 
 	/* If Master Write/Slave Read */
@@ -709,8 +709,9 @@ void TWI_attachSlaveRxEvent( void (*function)(int), uint8_t *read_data, uint8_t
  * Input    function: callback function to use
  * Output   none
  */
-void TWI_attachSlaveTxEvent( void (*function)(void) ){
+void TWI_attachSlaveTxEvent( uint8_t (*function)(void), uint8_t* write_data ){
   TWI_onSlaveTransmit = function;
+  slave_writeData = write_data;
 }
 
 

libraries/Wire/src/utility/twi.h

@@ -82,7 +82,7 @@ register8_t master_trans_status;                       /*!< Status of transactio
 register8_t master_result;                             /*!< Result of transaction */
 
 /* Slave variables */
-static void (*TWI_onSlaveTransmit)(void) __attribute__((unused));
+static uint8_t (*TWI_onSlaveTransmit)(void) __attribute__((unused));
 static void (*TWI_onSlaveReceive)(int) __attribute__((unused));
 register8_t* slave_writeData;
 register8_t* slave_readData;
@@ -135,7 +135,7 @@ void TWI_SlaveDataHandler(void);
 void TWI_SlaveWriteHandler(void);
 void TWI_SlaveReadHandler(void);
 void TWI_attachSlaveRxEvent( void (*function)(int), uint8_t *read_data, uint8_t bytes_to_read );
-void TWI_attachSlaveTxEvent( void (*function)(void) );
+void TWI_attachSlaveTxEvent( uint8_t (*function)(void), uint8_t *write_data );
 void TWI_SlaveTransactionFinished(uint8_t result);
 /*! TWI master interrupt service routine.
  *