Add buffer arg to TWI_MasterRead and avoid using master_readData in Wire.cpp

Author: sandeepmistry

libraries/Wire/src/Wire.cpp

@@ -100,12 +100,7 @@ uint8_t TwoWire::requestFrom(uint8_t address, size_t quantity, bool sendStop) {
 		quantity = BUFFER_LENGTH;
 	}
 
-	uint8_t bytes_read = TWI_MasterRead(address, quantity, sendStop);
-	
-	/* Copy read buffer from lower layer */
-	for(uint8_t i = 0; i < bytes_read; i++){
-		rxBuffer[i] = master_readData[i];
-	}
+	uint8_t bytes_read = TWI_MasterRead(address, rxBuffer, quantity, sendStop);
 
 	/* Initialize read variables */
 	rxBufferIndex = 0;

libraries/Wire/src/utility/twi.c

@@ -213,9 +213,12 @@ uint8_t TWI_MasterWrite(uint8_t slave_address,
  *  \retval false If transaction could not be started.
  */
 uint8_t TWI_MasterRead(uint8_t slave_address,
-                    uint8_t bytes_to_read,
+					uint8_t* read_data,
+					uint8_t bytes_to_read,
 					uint8_t send_stop)
 {
+	master_readData = read_data;
+
 	uint8_t bytes_read = TWI_MasterWriteRead(slave_address, 
 										  0, 
 										  0, 
@@ -252,9 +255,6 @@ uint8_t TWI_MasterWriteRead(uint8_t slave_address,
 	if (bytes_to_write > TWI_BUFFER_SIZE) {
 		return 1;
 	}
-	if (bytes_to_read > TWI_BUFFER_SIZE) {
-		return 0;
-	}
 
 	/*Initiate transaction if bus is ready. */
 	if (master_trans_status == TWIM_STATUS_READY) {
@@ -443,7 +443,7 @@ void TWI_MasterWriteHandler()
 void TWI_MasterReadHandler()
 {
 	/* Fetch data if bytes to be read. */
-	if (master_bytesRead < TWI_BUFFER_SIZE) {
+	if (master_bytesRead < master_bytesToRead) {
 		uint8_t data = TWI0.MDATA;
 		master_readData[master_bytesRead] = data;
 		master_bytesRead++;

libraries/Wire/src/utility/twi.h

@@ -75,7 +75,7 @@ typedef enum TWI_MODE_enum {
 /* Master variables */
 register8_t master_slaveAddress;                      /*!< Slave address */
 register8_t master_writeData[TWI_BUFFER_SIZE];  /*!< Data to write */
-register8_t master_readData[TWI_BUFFER_SIZE];    /*!< Read data */
+register8_t* master_readData;                          /*!< Read data */
 register8_t master_bytesToWrite;                       /*!< Number of bytes to write */
 register8_t master_bytesToRead;                        /*!< Number of bytes to read */
 register8_t master_bytesWritten;                       /*!< Number of bytes written */
@@ -116,6 +116,7 @@ uint8_t TWI_MasterWrite(uint8_t slave_address,
                      uint8_t bytes_to_write,
 					 uint8_t send_stop);
 uint8_t TWI_MasterRead(uint8_t slave_address,
+                    uint8_t* read_data,
                     uint8_t bytes_to_read,
 					uint8_t send_stop);
 uint8_t TWI_MasterWriteRead(uint8_t slave_address,