Change slave_writeData to be pointer and use buffer inside Wire.cpp

Author: sandeepmistry

libraries/Wire/src/Wire.cpp

@@ -181,39 +181,20 @@ uint8_t TwoWire::endTransmission(void)
 // or after beginTransmission(address)
 size_t TwoWire::write(uint8_t data)
 {
-	/* If master transmitter */
-	if(transmitting){
-
-		/* Check if buffer is full */
-		if(txBufferLength >= BUFFER_LENGTH){
-		  setWriteError();
-		  return 0;
-		}
-	
-		/* Put byte in txBuffer */
-		txBuffer[txBufferIndex] = data;
-		txBufferIndex++;
-	
-		/* Update buffer length */
-		txBufferLength = txBufferIndex;
-	
+	/* Check if buffer is full */
+	if(txBufferLength >= BUFFER_LENGTH){
+	  setWriteError();
+	  return 0;
 	}
-  
-	/* If slave transmitter */
-	else{
-
-		/* Check if buffer full */
-		if(slave_bytesToWrite >= TWI_BUFFER_SIZE){
-			setWriteError();
-			return 0;
-		}
 
-		slave_writeData[slave_bytesToWrite] = data;
-		slave_bytesToWrite++;
+	/* Put byte in txBuffer */
+	txBuffer[txBufferIndex] = data;
+	txBufferIndex++;
 
-	}
+	/* Update buffer length */
+	txBufferLength = txBufferIndex;
 
-	 return 1;
+	return 1;
 }
 
 // must be called in:
@@ -324,10 +305,14 @@ void TwoWire::onRequestService(void)
 	}
 
 	// reset slave write buffer iterator var
-	slave_bytesToWrite = 0;
+	txBufferIndex = 0;
+	txBufferLength = 0;
 
 	// alert user program
 	user_onRequest();
+
+	slave_bytesToWrite = txBufferLength;
+	slave_writeData = txBuffer;
 }
 
 // sets function called on slave write

libraries/Wire/src/utility/twi.c

@@ -644,7 +644,7 @@ void TWI_SlaveWriteHandler(){
 	/* If ACK, master expects more data */
 	else {		
 
-		if(slave_bytesWritten < TWI_BUFFER_SIZE){
+		if(slave_bytesWritten < slave_bytesToWrite){
 			uint8_t data = slave_writeData[slave_bytesWritten];
 			TWI0.SDATA = data;
 			slave_bytesWritten++;	

libraries/Wire/src/utility/twi.h

@@ -87,7 +87,7 @@ register8_t master_result;                             /*!< Result of transactio
 /* Slave variables */
 static void (*TWI_onSlaveTransmit)(void) __attribute__((unused));
 static void (*TWI_onSlaveReceive)(volatile uint8_t*, int) __attribute__((unused));
-register8_t slave_writeData[TWI_BUFFER_SIZE];
+register8_t* slave_writeData;
 register8_t slave_readData[TWI_BUFFER_SIZE];
 register8_t slave_bytesToWrite;
 register8_t slave_bytesWritten;