UART snippet for atmega328p

comm328p.c

#include <avr/io.h>
#include <stdlib.h>
#include <util/delay.h>
#include <inttypes.h>
#include "comm328p.h"

//Version for atmega328

uint8_t computc( uint8_t c )
{
    //Send single byte through UART
    //c - character to send

    while ( !( UCSR0A & ( 1 << UDRE0 ) ) );
    return UDR0 = c;
}

uint8_t comgetc( )
{
    //Receive and return single byte
    //Returned value: received character

	unsigned int i = 0;

	for ( i = 0; i < UART_TIMEOUT; i++ )
	{
    	if ( UCSR0A & ( 1 << RXC0 ) )
    		return UDR0;
		_delay_us( 1000000 / UART_BAUD * 10 );
	}

	return 0;
}

uint16_t computs( const char *s )
{
    //Send character word through UART
    //s - pointer to string
	uint16_t i = 0;

	while ( s[i] )
    	computc( s[i++] );
    	
    return i;
}

uint16_t comwrite( uint8_t *buff, uint16_t len )
{
    //Send character word through UART
    //s - pointer to string
	size_t i = 0;

	for ( i = 0; i < len; i++ )
		computc( buff[i] );
		
	return i;
}

uint16_t comread( char *buff, uint16_t bufflen )
{
    uint16_t i = 0, j = 0;

	for ( j = 0; j < UART_TIMEOUT; j++ )
	{
	    if ( UCSR0A & ( 1 << RXC0 ) )
		{
	    	buff[i] = UDR0;
			j = 0;

			i += i + 1 >= bufflen ? 0 : 1;
		}

		_delay_us( 1000000 / UART_BAUD * 10 );
	}

	buff[i] = 0;
	return i;
}


uint8_t comstatus( )
{
	//Is uart input buffer empty?

	return ( UCSR0A & ( 1 << RXC0 ) ) != 0;
}

void cominit( )
{
    //Init UART with given BAUD rate
	unsigned int baud = UART_BAUD;

	baud = F_CPU / 16 / baud - 1;

	UBRR0H = (unsigned char) ( baud >> 8 ); //Set BAUD rate
    UBRR0L = (unsigned char) baud;
    UCSR0B = ( 1 << RXEN0 ) | ( 1 << TXEN0 ); //Enable RX and TX
    UCSR0C = ( 0 << USBS0 ) | ( 3 << UCSZ00 ); //Set data format
}

comm328p.h

#ifndef UART_H
#define UART_H

#include <inttypes.h>

#ifndef UART_BAUD
#define UART_BAUD 9600
#warning Please define UART_BAUD value
#endif

#ifndef UART_TIMEOUT
#define UART_TIMEOUT 4
#warning Default UART_TIMEOUT value is 4
#endif

extern uint8_t computc( uint8_t c );
extern uint8_t comgetc( );
extern uint16_t computs( const char *s );
extern uint16_t comwrite( uint8_t *buff, uint16_t len );
extern uint16_t comread( char *buff, uint16_t bufflen );
extern uint8_t comstatus( );
extern void cominit( );


#endif