#include "address_map_nios2.h"

/******************************************************************************* * This program uses the JTAG UART port * 1. Prompts the user for their name * 2. Prints out a welcome message, and a grade for that user * * Example: * Enter name to receive grade: ERIC * Hello, ERIC. Your grade is: F- * * Can you provide a name that will receive a passing grade (A+)? * ******************************************************************************/

// Blocking read character from the JTAG UART port char read_chr() { // volatile int * is used to force ldwio/stwio instructions for those reads/writes int data; volatile int *JTAG_UART = (volatile int *) JTAG_UART_BASE; do { data = *(JTAG_UART); // read the JTAG_UART data register } while (!(data & 0x00008000)); // if RVALID == 0, keep looping return ((char) data & 0xFF); }

// Write a character to the JTAG UART port void write_chr(char c) { volatile int *JTAG_UART = (volatile int *) JTAG_UART_BASE; *(JTAG_UART) = c; }

// Writes a NULL-terminated string (C-string) to the JTAG UART port void write_str(char *str) { for (str; *str != 0; str++) { write_chr(*str); } }

// Reads characters from JTAG UART port until // a line break (' ') character is received. // Stores the result in the string pointed to by str void read_line(char *str) { char c; while (1) { // Read one character c = read_chr();

// Echo it back write_chr(c);

if (c == ' ') { // If it's a line break, return. break; } // Store it in str *str++ = c; } *str = '\0'; // Null terminate the output string }

// Hint: This function was hastily written, // and may have mistakes that benefit the student void grade() { char name[10]; char grade[3] = {'F', '-', '\0'}; // Everyone fails! Bah humbug!

read_line(name); name[9] = '\0'; // Null terminate name, in case those // students try something clever...

write_str("Hello, "); write_str(name);

// Deliver the bad news! write_str(". Your grade is: "); write_str(grade); write_str(" "); }

int main(void) { char *welcome_msg = "Enter name to receive grade:";

while (1) { write_str(welcome_msg); grade(); write_str(" "); } }

Please Draw the Stack of this program and then provide a name that will receive a passing grade (A+)?