function for configuring serial port options

Using Arduino Programming Questions
1

For any AVR experts out there,
I'm trying to build a function to allow a bit more capability than the standard serial.begin function of the Arduino IDE. I was wondering if this looks like I'm on the right track

#include <avr/io.h>

bool USARTbegin( int port, int baudRate, int dataBits, char parity, int stopBits )
{
	if(port == 0)
	{
		int clockCPU;
		int prescale;
		
		//basic setup
		UCSR0A = 0x20; //B00100000;
		UCSR0B = 0x0C; //B0001100
		UCSR0C = 0x06; //B0000110 default
		//change bits per settings
		
		//baud rate setting
		prescale = ((( clockCPU / ( baudRate * 16 UL))) - 1)
		UBRR0H = (prescale >> 8); //load upper 8 bits to high byte
		UBRR0L = (prescale);      //load lower 8bits to low byte
		
		
		//message databit setting
		if(dataBits == 9)
		{
			UCSR0B = (1<<UCSZ02);
			UCSR0C = (1<<UCSZ01) | (1<<UCSZ00);
		}
		else if(dataBits == 8)
		{
			UCSR0B = (0<<UCSZ02);
			UCSR0C = (1<<UCSZ01) | (1<<UCSZ00);
		}
		else if(dataBits == 7)
		{
			UCSR0B = (0<<UCSZ02);
			UCSR0C = (1<<UCSZ01) | (0<<UCSZ00);
		}
		else if(dataBits == 6)
		{
			UCSR0B = (0<<UCSZ02);
			UCSR0C = (0<<UCSZ01) | (1<<UCSZ00);
		}
		else if(dataBits == 5)
		{
			UCSR0B = (0<<UCSZ02);
			UCSR0C = (0<<UCSZ01) | (0<<UCSZ00);
		}
		else
		{
			return false;
		}//end of data bit
		
		//parity setting
		if(parity == o || parity == O)
		{
			UCSR0C = (1<<UPM01) | (1<<UPM00);
		}
		else if(parity == e || parity == E)
		{
			UCSR0C = (1<<UPM01) | (0<<UPM00);
		}
		else if(parity == n || parity == N)
		{
			UCSR0C = (0<<UPM01) | (0<<UPM00);
		}
		else
		{
			return false;
		}//end of parity
		
		//stop bits
		if(stopBits == 1)
		{
			UCSR0C = (0<<USBS0);
		}
		else if(stopBits == 2)
		{
			UCSR0C = (1<<USBS0);
		}
		else
		{
			return false;
		}//end of stop bits
		
	}//end of port number
	
	
	return true;
}

I realize that reading 9 bits of data requires pulling 1 bit from one of the UCSR's then reading UBR. Right now I don't ever forsee using 9 bit data length.
One thing I cannot figure out from the mega datashett, how can you tell how many bytes are currently in the recieve buffer?
thanks

2

Have you seen this page ? Serial.begin() - Arduino Reference

3

Yes, the latest serial.begin offers a lot of options (but not 9 bit handling).

Also the serial.available functions returns a int value of how many bytes are presently available in the receive buffer.

Lefty