#include "address_map_nios2.h"
#include <stdio.h>

/* function prototypes */
void put_jtag(volatile int *, char);
int change(volatile int *, char);

/********************************************************************************
 * This program demonstrates use of the JTAG UART port
 *
 * It performs the following:
 *      1. sends a text string to the JTAG UART
 *  2. reads character data from the JTAG UART
 *  3. echos the character data back to the JTAG UART
********************************************************************************/
int main(void)
{
    /* Declare volatile pointers to I/O registers (volatile means that IO load
       and store instructions will be used to access these pointer locations,
       instead of regular memory loads and stores) */
    volatile int * JTAG_UART_ptr    = (int *) JTAG_UART_BASE;   // JTAG UART address

    int data, i;
    char text_string[] = "\nJTAG UART example code\n> \0";

    /* print a text string */
    for (i = 0; text_string[i] != 0; ++i)
        //put_jtag (JTAG_UART_ptr, text_string[i]);

    /* read and echo characters */
    while(1)
    {
        data = *(JTAG_UART_ptr);                // read the JTAG_UART data register
        if (data & 0x00008000)                  // check RVALID to see if there is new data
        {
            data = data & 0x000000FF;           // the data is in the least significant byte
            change (JTAG_UART_ptr, (char) data & 0xFF);
            /* echo the character */
            put_jtag (JTAG_UART_ptr, (char) data & 0xFF );
        }
    }
}

/********************************************************************************
 * Subroutine to send a character to the JTAG UART
********************************************************************************/
int change(volatile int  * JTAG_UART_ptr, char c)
{
    int control;
    int counter = 0;
    control = *(JTAG_UART_ptr + 1);         // read the JTAG_UART control register
    if (control & 0xFFFF0000)                   // if space, then echo character, else ignore

    if (c == 0x30 /*&& control <= 0x39*/)
    {
        c = c & 0x09;
        //c =
        *(JTAG_UART_ptr) = c;
    }

    else {
    put_jtag( volatile int * JTAG_UART_ptr, char c );
    {
        int control;
        control = *(JTAG_UART_ptr + 1);         // read the JTAG_UART control register
        if (control & 0xFFFF0000)                   // if space, then echo character, else ignore
            *(JTAG_UART_ptr) = c;
    }
    }
}