simtest.c

/* This port correponds to the "-W 0x20,-" command line option. */
#define special_output_port (*((volatile char *)0x20))

/* This port correponds to the "-R 0x22,-" command line option. */
#define special_input_port  (*((volatile char *)0x22))


#define F_CPU 16000000L
#include <avr/delay.h>

/* Poll the specified string out the debug port. */
void debug_puts(const char *str) {
	const char *c;

	for(c = str; *c; c++)
		special_output_port = *c;
}

/* Main for test program.  Enter a string and echo it. */
int main() {
	volatile char in_char;

	/* Output the prompt string */
	debug_puts("\nPress any key and enter:\n> ");

	/* Input one character but since line buffered, blocks until a CR. */
	in_char = special_input_port;
	char c = 30;
	int i ;
	for(i=0;i<100;i++){
		if (in_char==0x30){
			special_output_port = c++;
			special_output_port = '\n';
			_delay_ms(1000);
		}
	}

	/* Print the "what you entered:" message. */
	debug_puts("\nYou entered: ");

	/* now echo the rest of the characters */
	do {
		special_output_port = in_char;
	} while((in_char = special_input_port) != '\n');

	special_output_port = '\n';
	special_output_port = '\n';

	return 0;
}