#if ((CHIPSET != 5) && (CHIPSET != 6))
    /*
     * Enable sleep mode.
     */

    WRITE_UART_REGISTER (uart, IER, IER_SLEEP);
#endif
}


/*******************************************************************************
 *
 *                               UA_Init
 * 
 * Purpose  : Initializes the module and the UART.
 *
 * Arguments: In : uart_id : UART id.
 *                 baudrate: baud rate selected.
 *                 callback: user's function called characters are received.
 *            Out: none
 *
 * Returns: none
 *
 * Warning: Parameters are not verified.
 *
 ******************************************************************************/

void
UA_Init (T_tr_UartId uart_id,
         T_tr_Baudrate baudrate,
         void (callback_function (void)))
{
    t_uart *uart;
    int    index;

    for (index = 0; index < NUMBER_OF_TR_UART; index++)
        uart_parameter[index].base_address = base_address[index];
        
    uart = &(uart_parameter[uart_id]);

    uart->rx_in  = &(uart->rx_buffer[0]);
    uart->rx_out = &(uart->rx_buffer[0]);

    uart->callback_function = callback_function;

    uart->framing_error = 0;
    uart->parity_error  = 0;
    uart->overrun_error = 0;

    uart->dle_detected = 0;
    uart->inframe = 0;
    uart->encapsulation_flag = 0;
    uart->frame_length = 0;

    /*
     * Mask all interrupts causes and disable sleep mode.
     */

    WRITE_UART_REGISTER (uart, IER, 0x00);

    /*
     * Reset UART mode configuration.
     */
     
    WRITE_UART_REGISTER (uart, MDR1, RESET_DEFAULT_STATE   |
                                     IR_SLEEP_DISABLED     |
                                     SIR_TX_WITHOUT_ACREG2 |
                                     FRAME_LENGTH_METHOD);

    /*
     * FIFO configuration.
     * EFR[4] = 1 to allow to program FCR[5:4] and MCR[7:5].
     */
     
    WRITE_UART_REGISTER (uart, LCR, 0xBF);
    SET_BIT (uart, EFR, ENHANCED_FEATURE_BIT);

    /*
     * Select the word length, the number of stop bits , the parity and set
     * LCR[7] (DLAB) to allow to program FCR, DLL and DLM.
     */

    WRITE_UART_REGISTER (uart, LCR, WLS_8 | DLAB);

    /*
     * Program the trigger levels.
     * MCR[6] must be set to 1.
     */
     
    SET_BIT (uart, MCR, TCR_TLR_BIT);
    WRITE_UART_REGISTER (uart, TCR, 0x0F);
    WRITE_UART_REGISTER (
        uart, TLR, RX_FIFO_TRIGGER_LEVEL);
    
    /*
     * Program the FIFO control register. Bit 0 must be set when other FCR bits
     * are written to or they are not programmed.
     * FCR is a write-only register. It will not be modified.
     */

    WRITE_UART_REGISTER (uart, FCR, FIFO_ENABLE   |
                                    RX_FIFO_RESET | /* self cleared */
                                    TX_FIFO_RESET); /* self cleared */

    /*
     * Program the baud generator.
     */

    WRITE_UART_REGISTER (uart, DLL, dll[baudrate]);
    WRITE_UART_REGISTER (uart, DLM, dlh[baudrate]);

    
    /*
     * Reset LCR[7] (DLAB) to have access to the RBR, THR and IER registers.
     */

    WRITE_UART_REGISTER (uart, LCR, READ_UART_REGISTER (uart, LCR) & ~DLAB);


    /*
     * Select UART mode.
     */
     
    WRITE_UART_REGISTER (uart, MDR1, UART_MODE             |
                                     IR_SLEEP_DISABLED     |
                                     SIR_TX_WITHOUT_ACREG2 |
                                     FRAME_LENGTH_METHOD);

#if ((CHIPSET == 5) || (CHIPSET == 6))
    /*
     * Unmask RX interrupt
     */

    WRITE_UART_REGISTER (uart, IER, ERBI);
#else
    /*
     * Unmask RX interrupt and allow sleep mode.
     */

    WRITE_UART_REGISTER (uart, IER, ERBI | IER_SLEEP);
#endif
}

/*******************************************************************************
 *
 *                           UA_ReadNChars
 * 
 * Purpose  : Reads N characters from the RX buffer.
 *
 * Arguments: In : uart_id      : UART id.
 *                 buffer       : buffer address where the characters are
 *                                copied.
 *                 chars_to_read: number of characters to read.
 *            Out: none
 *
 * Returns  : The number of characters read.
 *
 * Warning: Parameters are not verified.
 *
 ******************************************************************************/

SYS_UWORD32
UA_ReadNChars (T_tr_UartId uart_id,
               char *buffer,
               SYS_UWORD32 chars_to_read)
{
    SYS_UWORD32 chars_in_rx_buffer;
    SYS_UWORD32 chars_to_copy;
    SYS_UWORD32 chars_written;
    char        *rx_in;
    t_uart      *uart;
    
    uart = &(uart_parameter[uart_id]);

    /*
     * A copy of the rx_in pointer is used because it may be updated by
     * the interrupt handler.
     * Get the number of bytes available in the RX buffer.
     */
         
    rx_in = uart->rx_in;

    if (uart->rx_out <= rx_in)
        chars_in_rx_buffer = (SYS_UWORD32) (rx_in - uart->rx_out);
    else
        chars_in_rx_buffer = (SYS_UWORD32) (rx_in - uart->rx_out + BUFFER_SIZE + 1);

    /*
     * No more bytes than those received may be written in the output buffer.
     */

    if (chars_in_rx_buffer >= chars_to_read)
        chars_to_copy = chars_to_read;
    else
        chars_to_copy = chars_in_rx_buffer;

    chars_written = chars_to_copy;

    /*
     * Write the received bytes in the output buffer.
     */

    while (chars_to_copy) {

        *(buffer++) = *(uart->rx_out++);
        chars_to_copy--;

        if (uart->rx_out == &(uart->rx_buffer[0]) + BUFFER_SIZE + 1)
            uart->rx_out = &(uart->rx_buffer[0]);
    }

    return (chars_written);
}

/*******************************************************************************
 *
 *                           UA_ReadNBytes
 * 
 * Purpose  : Reads and destuff N bytes from the RX buffer.
 *
 * Arguments: In : uart_id      : UART id.
 *                 buffer       : buffer address where the bytes are copied.
 *                 chars_to_read: number of bytes to read.
 *            Out: eof_detected : indicates if an EOF has been detected.
 *
 * Returns  : The number of bytes read.
 *
 * Warning: Parameters are not verified.
 *
 ******************************************************************************/

SYS_UWORD32
UA_ReadNBytes (T_tr_UartId uart_id,
               char *buffer,
               SYS_UWORD32 bytes_to_read,
               SYS_BOOL *eof_detected)
{
    SYS_UWORD32 bytes_in_rx_buffer;
    SYS_UWORD32 bytes_to_process;
    SYS_UWORD32 bytes_written;
    char        *rx_in;
    t_uart      *uart;
    
    bytes_written = 0;
    uart = &(uart_parameter[uart_id]);

    /*
     * A copy of the rx_in pointer is used because it may be updated by
     * the interrupt handler.
     * Get the number of bytes available in the RX buffer.
     */
         
    rx_in = uart->rx_in;

    if (uart->rx_out <= rx_in)
        bytes_in_rx_buffer = (SYS_UWORD32) (rx_in - uart->rx_out);
    else
        bytes_in_rx_buffer = (SYS_UWORD32) (rx_in - uart->rx_out + BUFFER_SIZE + 1);

    /*
     * No more bytes than those received may be processed and then written in
     * the output buffer.
     */

    if (bytes_in_rx_buffer >= bytes_to_read)
        bytes_to_process = bytes_to_read;
    else
        bytes_to_process = bytes_in_rx_buffer;

    /*
     * Perform the byte destuffing and then write the "valid" received bytes in
     * the output buffer.
     */

    while ((bytes_to_process) && !(*eof_detected)) {

        switch (*(uart->rx_out)) {                                                                       

            /*
             * Current byte is DLE.
             */  

            case DLE:
                                                        
                if (!uart->dle_detected) {

                    /*
                     * No DLE previously detected => 
                     * Skip the current byte and set the flag.
                     */

                    uart->dle_detected = 1;
                    bytes_to_process--;
                    uart->rx_out++;
                }

                else { /* if (uart->dle_detected) */

                    if (uart->inframe) {

                        /*
                         * DLE previously detected AND currently inside of a frame =>
                         * Copy the current byte in the output buffer, reset the flag
                         * and increase the frame length.
                         */

                        uart->dle_detected = 0;
                        bytes_to_process--;
                        uart->frame_length++;
                        *(buffer++) = *(uart->rx_out++);
                        bytes_written++;
                    }                                       

                    else { /* if (!uart->inframe) */

                        /*
                         * DLE previously detected AND currently outside of a frame =>
                         * Skip the current byte.
                         */

                        bytes_to_process--;
                        uart->rx_out++;
                    }
                }

            break; /* case DLE */
                                                                                
            /*
             * Current byte is STX.
             */  

            case STX:
                                                      
                if ((!uart->dle_detected) && (uart->inframe)) {

                    /*
                     * No DLE previously detected AND currently inside of a frame.
                     */

                    if (uart->frame_length) {

                        /*
                         * Frame length is not zero (End of Frame) => 
                         * Skip the current byte and set the flags (EOF).
                         */

                        uart->inframe = 0;
                        *eof_detected = 1;
                        uart->frame_length = 0;
                        bytes_to_process--;
                        uart->rx_out++;
                    }

                    else { /* if (!uart->frame_length) */

                        /*
                         * Frame length is zero (STX followed by another STX =
                         * Synchro lost but start of a new frame) =>
                         * Skip the current byte and keep the flag set.
                         */

                        bytes_to_process--;
                        uart->rx_out++;
                    }
                }

                else if ((!uart->dle_detected) && (!uart->inframe)) {

                    /*
                     * No DLE previously detected AND currently outside of a
                     * frame (Start of Frame) =>
                     * Skip the current byte and set the flag.
                     */

                    uart->inframe = 1;
                    bytes_to_process--;
                    uart->rx_out++;
                }

                else if ((uart->dle_detected) && (uart->inframe)) {

                    /*
                     * DLE previously detected AND currently inside of a frame =>
                     * Copy the current byte in the output buffer, reset the flag
                     * and increase the frame length.
                     */

                    uart->dle_detected = 0;
                    bytes_to_process--;
                    uart->frame_length++;
                    *(buffer++) = *(uart->rx_out++);
                    bytes_written++;
                }                                       

                else if ((uart->dle_detected) && (!uart->inframe)) {

                    /*
                     * DLE previously detected AND currently outside of a frame =>
                     * Skip the current byte and reset the flag.
                     */

                    uart->dle_detected = 0;
                    bytes_to_process--;
                    uart->rx_out++;
                }

            break; /* case STX */

            /*
             * Current byte is neither DLE nor STX.
             */  

            default:

                if (uart->inframe) {

                    /*
                     * Currently inside of a frame =>
                     * Copy the current byte in the output buffer and increase
                     * the frame length.
                     */

                    bytes_to_process--;
                    uart->frame_length++;
                    *(buffer++) = *(uart->rx_out++);
                    bytes_written++;
                }                                       

                else { /* if (!uart->inframe) */

                    /*
                     * Currently outside of a frame =>
                     * Skip the current byte.
                     */

                    bytes_to_process--;
                    uart->rx_out++;
                }

            break; /* default */
        }

        if (uart->rx_out == &(uart->rx_buffer[0]) + BUFFER_SIZE + 1)
            uart->rx_out = &(uart->rx_buffer[0]);
    }

    return (bytes_written);
}


/*******************************************************************************
 *
 *                           UA_WriteNChars
 * 
 * Purpose  : Writes N characters in the TX FIFO.
 *
 * Arguments: In : uart_id       : UART id.
 *                 buffer        : buffer address from which characters are
 *                                 written.
 *                 bytes_to_write: number of bytes to write.
 *            Out: none
 *
 * Returns  : Number of bytes written.
 *
 * Warning: Parameters are not verified.
 *
 ******************************************************************************/

SYS_UWORD32
UA_WriteNChars (T_tr_UartId uart_id,
                char *buffer,
                SYS_UWORD32 chars_to_write)
{