this is me ... and i prefer to say hello world by following program :
#include
#include
#include "sys/alt_alarm.h"
#include "system.h"
#include "nios2.h"
#include "altera_avalon_mutex.h"
#define MESSAGE_WAITING 1
#define NO_MESSAGE 0
#define LOCK_SUCCESS 0
#define LOCK_FAIL 1
#define MESSAGE_BUFFER_BASE MESSAGE_BUFFER_RAM_BASE
#define FIRST_LOCK 1 /* for testing only */
#define ERROR_OPENED_INVALID_MUTEX 1 /* for testing only */
#define ERROR_ALLOWED_ACCESS_WITHOUT_OWNING_MUTEX 2 /* for testing only */
#define ERROR_COULDNT_OPEN_MUTEX 3 /* for testing only */
#define MS_DELAY 1000
// Message buffer structure
typedef struct {
char flag;
char buf[100];
} message_buffer_struct;
int main()
{
// Pointer to our mutex device
alt_mutex_dev* mutex = NULL;
// Local variables
unsigned int id;
unsigned int value;
unsigned int count = 0;
unsigned int ticks_at_last_message;
char got_first_lock = 0; /* for testing only */
unsigned int error_code = 0; /* for testing only */
message_buffer_struct *message;
// Get our processor ID (add 1 so it matches the cpu name in SOPC Builder)
NIOS2_READ_CPUID(id);
id += 1;
// Value can be any non-zero value
value = 1;
// Initialize the message buffer location
message = (message_buffer_struct*)MESSAGE_BUFFER_BASE;
// We'll try to open the wrong mutex here and hope it's not successful.
mutex = altera_avalon_mutex_open("/dev/wrong_device_name"); /* for testing only */
if (mutex != NULL) /* for testing only */
{
// Whoops, opening the invalid mutex was successful.
error_code = ERROR_OPENED_INVALID_MUTEX; /* for testing only */
goto error; /* for testing only */
}
// Okay, now we'll open the real mutex
// It's not actually a mutex to share the jtag_uart, but to share a message
// buffer which CPU1 is responsible for reading and printing to the jtag_uart.
mutex = altera_avalon_mutex_open(MESSAGE_BUFFER_MUTEX_NAME);
// We'll use the system clock to keep track of our delay time.
// Here we initialize delay tracking variable.
ticks_at_last_message = alt_nticks();
if (mutex)
{
// If the mutex has never been locked, clear the message flag.
// We are safe to use the non-blocking "trylock" function here
// because if we dont get the mutex on the first shot, it means
// someone else already has it and we clearly arent going to be
// the first to release it anyway.
if(altera_avalon_mutex_trylock(mutex, value) == LOCK_SUCCESS) /* for testing only */
{
if (altera_avalon_mutex_first_lock(mutex) == FIRST_LOCK) /* for testing only */
{
message->flag = NO_MESSAGE; /* for testing only */
got_first_lock = 1; /* for testing only */
}
altera_avalon_mutex_unlock(mutex); /* for testing only */
}
while(1)
{
// See if it's time to send a message yet
if (alt_nticks() >= (ticks_at_last_message + ((alt_ticks_per_second() * (MS_DELAY)) / 1000)))
{
ticks_at_last_message = alt_nticks();
// Try and aquire the mutex (non-blocking).
if(altera_avalon_mutex_trylock(mutex, value) == LOCK_SUCCESS)
{
// Just make sure we own the mutex
if(altera_avalon_mutex_is_mine(mutex)) /* for testing only */
{
// Check if the message buffer is empty
if(message->flag == NO_MESSAGE)
{
count++;
// If we were the first to lock the mutex, say so in our first message.
if (got_first_lock) /* for testing only */
{
sprintf(message->buf, "FIRST LOCK - Message from CPU %d. Number sent: %d\n", id, count); /* for testing only */
got_first_lock = 0; /* for testing only */
}
else
{
sprintf(message->buf, "Message from CPU %d. Number sent: %d\n", id, count);
}
// Set the flag that a message has been put in the buffer.
message->flag = MESSAGE_WAITING;
}
}
else /* for testing only */
{
error_code = ERROR_ALLOWED_ACCESS_WITHOUT_OWNING_MUTEX; /* for testing only */
goto error; /* for testing only */
}
// Release the mutex
altera_avalon_mutex_unlock(mutex);
}
}
// If we are CPU1, check the message buffer
// and if there's a message, print it to stdout.
// if(id == 1)
#ifdef JTAG_UART_NAME
{
if(message->flag == MESSAGE_WAITING)
{
// We dont really need to lock the mutex here since the if(id == 1) statement
// assures we are the only CPU grabbing messages out of the buffer, but
// we'll do it anyway to test the blocking lock routine.
altera_avalon_mutex_lock(mutex, value); /* for testing only */
// Just make sure we own the mutex
if(altera_avalon_mutex_is_mine(mutex)) /* for testing only */
{
printf("%s", message->buf);
message->flag = NO_MESSAGE;
}
else /* for testing only */
{
error_code = ERROR_ALLOWED_ACCESS_WITHOUT_OWNING_MUTEX; /* for testing only */
goto error; /* for testing only */
}
// Release the Mutex
altera_avalon_mutex_unlock(mutex); /* for testing only */
}
}
#endif /* JTAG_UART_NAME */
}
}
else /* for testing only */
{
error_code = ERROR_COULDNT_OPEN_MUTEX; /* for testing only */
goto error; /* for testing only */
}
error: /* for testing only */
return(error_code); /* for testing only */
// return(0);
}
