"uart.h" file for serial data transfer using Atmega16/32

#ifndef UART_H
#define UART_H
#if (__GNUC__ * 100 + __GNUC_MINOR__) < 304
#error "This library requires AVR-GCC 3.4 or later, update to newer AVR-GCC compiler !"
#endif

/*----------------------------------------------------------------
-----------------constants and macros-----------------------------
-----------------------------------------------------------------*/
/** @brief  UART Baudrate Expression
 *  @param  xtalcpu  system clock in Mhz, e.g. 4000000L for 4Mhz         
 *  @param  baudrate baudrate in bps, e.g. 1200, 2400, 9600    
 */
#define UART_BAUD_SELECT(baudRate,xtalCpu) ((xtalCpu)/((baudRate)*16l)-1)
/** @brief  UART Baudrate Expression for ATmega double speed mode
 *  @param  xtalcpu  system clock in Mhz, e.g. 4000000L for 4Mhz          
 *  @param  baudrate baudrate in bps, e.g. 1200, 2400, 9600    
 */
#define UART_BAUD_SELECT_DOUBLE_SPEED(baudRate,xtalCpu) (((xtalCpu)/((baudRate)*8l)-1)|0x8000)

/** Size of the circular receive buffer, must be power of 2 */
#ifndef UART_RX_BUFFER_SIZE
#define UART_RX_BUFFER_SIZE 256
#endif
/** Size of the circular transmit buffer, must be power of 2 */
#ifndef UART_TX_BUFFER_SIZE
#define UART_TX_BUFFER_SIZE 32
#endif
/* test if the size of the circular buffers fits into SRAM */
#if ( (UART_RX_BUFFER_SIZE+UART_TX_BUFFER_SIZE) >= (RAMEND-0x60 ) )
#error "size of UART_RX_BUFFER_SIZE + UART_TX_BUFFER_SIZE larger than size of SRAM"
#endif
/*
** high byte error return code of uart_getc()
*/
#define UART_FRAME_ERROR      0x0800              /* Framing Error by UART       */
#define UART_OVERRUN_ERROR    0x0400              /* Overrun condition by UART   */
#define UART_BUFFER_OVERFLOW  0x0200              /* receive ringbuffer overflow */
#define UART_NO_DATA          0x0100              /* no receive data available   */

/*
** function prototypes
*/

//Added by pulkit - clears the buffer
extern void clearBuffer();
/**
   @brief   Initialize UART and set baudrate
   @param   baudrate Specify baudrate using macro UART_BAUD_SELECT()
   @return  none
*/
extern void uart_init(unsigned int baudrate);

/**
 *  @brief   Get received byte from ringbuffer
 *
 * Returns in the lower byte the received character and in the
 * higher byte the last receive error.
 * UART_NO_DATA is returned when no data is available.
 *
 *  @param   void
 *  @return  lower byte:  received byte from ringbuffer
 *  @return  higher byte: last receive status
 *           - \b 0 successfully received data from UART
 *           - \b UART_NO_DATA          
 *             <br>no receive data available
 *           - \b UART_BUFFER_OVERFLOW  
 *             <br>Receive ringbuffer overflow.
 *             We are not reading the receive buffer fast enough,
 *             one or more received character have been dropped
 *           - \b UART_OVERRUN_ERROR    
 *             <br>Overrun condition by UART.
 *             A character already present in the UART UDR register was
 *             not read by the interrupt handler before the next character arrived,
 *             one or more received characters have been dropped.
 *           - \b UART_FRAME_ERROR      
 *             <br>Framing Error by UART
 */
extern unsigned int uart_getc(void);

/**
 *  @brief   Put byte to ringbuffer for transmitting via UART
 *  @param   data byte to be transmitted
 *  @return  none
 */
extern void uart_putc(unsigned char data);

/**
 *  @brief   Put string to ringbuffer for transmitting via UART
 *
 *  The string is buffered by the uart library in a circular buffer
 *  and one character at a time is transmitted to the UART using interrupts.
 *  Blocks if it can not write the whole string into the circular buffer.
 *
 *  @param   s string to be transmitted
 *  @return  none
 */
extern void uart_puts(const char *s );

/**
 * @brief    Put string from program memory to ringbuffer for transmitting via UART.
 *
 * The string is buffered by the uart library in a circular buffer
 * and one character at a time is transmitted to the UART using interrupts.
 * Blocks if it can not write the whole string into the circular buffer.
 *
 * @param    s program memory string to be transmitted
 * @return   none
 * @see      uart_puts_P
 */
extern void uart_puts_p(const char *s );
/**
 * @brief    Macro to automatically put a string constant into program memory
 */
#define uart_puts_P(__s)       uart_puts_p(PSTR(__s))

/** @brief  Initialize USART1 (only available on selected ATmegas) @see uart_init */
extern void uart1_init(unsigned int baudrate);
/** @brief  Get received byte of USART1 from ringbuffer. (only available on selected ATmega) @see uart_getc */
extern unsigned int uart1_getc(void);
/** @brief  Put byte to ringbuffer for transmitting via USART1 (only available on selected ATmega) @see uart_putc */
extern void uart1_putc(unsigned char data);
/** @brief  Put string to ringbuffer for transmitting via USART1 (only available on selected ATmega) @see uart_puts */
extern void uart1_puts(const char *s );
/** @brief  Put string from program memory to ringbuffer for transmitting via USART1 (only available on selected ATmega) @see uart_puts_p */
extern void uart1_puts_p(const char *s );
/** @brief  Macro to automatically put a string constant into program memory */
#define uart1_puts_P(__s)       uart1_puts_p(PSTR(__s))
/**@}*/

#endif // UART_H