Make slave_readData a point and pass buffer + size into TWI_attachSlaveRxEvent

Author: sandeepmistry

libraries/Wire/src/Wire.cpp

@@ -76,7 +76,7 @@ void TwoWire::begin(uint8_t address)
 	TWI_SlaveInit(address);
 
 	TWI_attachSlaveTxEvent(onRequestService); // default callback must exist
-	TWI_attachSlaveRxEvent(onReceiveService); // default callback must exist
+	TWI_attachSlaveRxEvent(onReceiveService, rxBuffer, BUFFER_LENGTH); // default callback must exist
 
 }
 
@@ -269,7 +269,7 @@ void TwoWire::flush(void)
 }
 
 // behind the scenes function that is called when data is received
-void TwoWire::onReceiveService(volatile uint8_t* inBytes, int numBytes)
+void TwoWire::onReceiveService(int numBytes)
 {
 	// don't bother if user hasn't registered a callback
 	if(!user_onReceive){
@@ -281,13 +281,7 @@ void TwoWire::onReceiveService(volatile uint8_t* inBytes, int numBytes)
 	if(rxBufferIndex < rxBufferLength){
 		return;
 	}
-	
-	// copy twi rx buffer into local read buffer
-	// this enables new reads to happen in parallel
-	for(uint8_t i = 0; i < numBytes; ++i){
-		rxBuffer[i] = inBytes[i];    
-	}
-	
+
 	// set rx iterator vars
 	rxBufferIndex = 0;
 	rxBufferLength = numBytes;

libraries/Wire/src/Wire.h

@@ -45,7 +45,7 @@ class TwoWire : public HardwareI2C
     static void (*user_onRequest)(void);
     static void (*user_onReceive)(int);
     static void onRequestService(void);
-    static void onReceiveService(volatile uint8_t*, int);
+    static void onReceiveService(int);
   public:
     TwoWire();
     void begin();

libraries/Wire/src/utility/twi.c

@@ -512,7 +512,7 @@ void TWI_SlaveInterruptHandler(){
 		 * This should be hit when there is a STOP or REPSTART 
 		 */
 		if(slave_callUserReceive == 1){
-			TWI_onSlaveReceive(slave_readData, slave_bytesRead);
+			TWI_onSlaveReceive(slave_bytesRead);
 			slave_callUserReceive = 0;
 		}
 
@@ -673,7 +673,7 @@ void TWI_SlaveWriteHandler(){
 void TWI_SlaveReadHandler(){
 
 	/* If free space in buffer */
-	if(slave_bytesRead < TWI_BUFFER_SIZE){
+	if(slave_bytesRead < slave_bytesToRead){
 
 		/* Fetch data */
 		uint8_t data = TWI0.SDATA;
@@ -697,8 +697,10 @@ void TWI_SlaveReadHandler(){
  * Input    function: callback function to use
  * Output   none
  */
-void TWI_attachSlaveRxEvent( void (*function)(volatile uint8_t*, int) ){
+void TWI_attachSlaveRxEvent( void (*function)(int), uint8_t *read_data, uint8_t bytes_to_read ){
   TWI_onSlaveReceive = function;
+  slave_readData = read_data;
+  slave_bytesToRead = bytes_to_read;
 }
 
 /* 

libraries/Wire/src/utility/twi.h

@@ -65,9 +65,6 @@ typedef enum TWI_MODE_enum {
 	TWI_MODE_SLAVE_RECEIVE = 6
 } TWI_MODE_t;
 
-/*! Buffer size define */
-#define TWI_BUFFER_SIZE         128
-
 /*! For adding R/_W bit to address */
 #define ADD_READ_BIT(address)	(address | 0x01)
 #define ADD_WRITE_BIT(address)  (address & ~0x01)
@@ -86,11 +83,12 @@ 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));
+static void (*TWI_onSlaveReceive)(int) __attribute__((unused));
 register8_t* slave_writeData;
-register8_t slave_readData[TWI_BUFFER_SIZE];
+register8_t* slave_readData;
 register8_t slave_bytesToWrite;
 register8_t slave_bytesWritten;
+register8_t slave_bytesToRead;
 register8_t slave_bytesRead;
 register8_t slave_trans_status;
 register8_t slave_result;
@@ -136,7 +134,7 @@ void TWI_SlaveStopHandler(void);
 void TWI_SlaveDataHandler(void);
 void TWI_SlaveWriteHandler(void);
 void TWI_SlaveReadHandler(void);
-void TWI_attachSlaveRxEvent( void (*function)(volatile uint8_t*, int) );
+void TWI_attachSlaveRxEvent( void (*function)(int), uint8_t *read_data, uint8_t bytes_to_read );
 void TWI_attachSlaveTxEvent( void (*function)(void) );
 void TWI_SlaveTransactionFinished(uint8_t result);
 /*! TWI master interrupt service routine.