Reading external data using On-chip FIFO and NIOS II

Hi ted,

I changed the ISR scheme from legacy to HAL Scheme. When I press the button the WRITE signal goes HIGH thus generating the interrupt. The interrupt occurs but the status isn't good after pressing the button.

# include "alt_types.h"
# include "altera_avalon_fifo_util.h"
# include "altera_avalon_pio_regs.h"
# include "altera_avalon_fifo_regs.h"
# include "sys/alt_irq.h"
# include "system.h"
# include <stdio.h>
# include <unistd.h>
# define IN_CSR_ADDRESS  0x2001800
# define OUT_CSR_ADDRESS 0x2001820
# define OUT_ADDRESS     0x2001878
volatile int edge_capture;
volatile alt_u8 global; //SDRAM
volatile int interrupted = 0;
//static void handle_input_fifo_wrclk_interrupts(void* context, alt_u32 id)
static void handle_input_fifo_wrclk_interrupts(void* context)
{
	volatile int* input_fifo_wrclk_irq_event_ptr = (volatile int*) context;
	*input_fifo_wrclk_irq_event_ptr = altera_avalon_fifo_read_event(IN_CSR_ADDRESS, ALTERA_AVALON_FIFO_EVENT_ALL);
	altera_avalon_fifo_clear_event(IN_CSR_ADDRESS, ALTERA_AVALON_FIFO_EVENT_ALL);
	altera_avalon_fifo_clear_event(OUT_CSR_ADDRESS, ALTERA_AVALON_FIFO_EVENT_ALL);
	altera_avalon_fifo_clear_event(OUT_ADDRESS, ALTERA_AVALON_FIFO_EVENT_ALL);
	interrupted = 1;
}
volatile int input_fifo_wrclk_irq_event;
int init_input_fifo()
{
	int code = ALTERA_AVALON_FIFO_OK;
	code = altera_avalon_fifo_init(IN_CSR_ADDRESS,  // Address
								   0x3F, 	   		// Enable interrupts
								   500, 	   		// Almost empty
								   1000); 	   		// Almost full
	code = altera_avalon_fifo_init(OUT_CSR_ADDRESS, // Address
								   0x3F, 	  		// Enable interrupts
								   500, 	  		// Almost empty
								   1000); 	  		// Almost full
	printf("ALMOSTEMPTY = %d\n", altera_avalon_fifo_read_almostempty(IN_CSR_ADDRESS));
	printf("ALMOSTFULL = %d\n", altera_avalon_fifo_read_almostfull(IN_CSR_ADDRESS));
	printf("STATUS = %d\n", altera_avalon_fifo_read_status(IN_CSR_ADDRESS, ALTERA_AVALON_FIFO_STATUS_REG));
	void* edge_capture_ptr = (void*) &edge_capture;
	alt_ic_isr_register(0, 16, handle_input_fifo_wrclk_interrupts, edge_capture_ptr, NULL); //IN_CSR_IRQ
	alt_ic_isr_register(0, 17, handle_input_fifo_wrclk_interrupts, edge_capture_ptr, NULL); //OUT_CSR_IRQ
	return code;
}
int main(void)
{
	init_input_fifo();
    while(1)
    {
    	if (interrupted)
    	{
    		alt_u32 level = altera_avalon_fifo_read_level(0x2001800);
    		printf("LEVEL: %u\n", level);
    		printf("STATUS = %d\n", altera_avalon_fifo_read_status(IN_CSR_ADDRESS, ALTERA_AVALON_FIFO_STATUS_REG));
    		printf("\n");
    		interrupted = 0;
    	}
    }
    return 0;
}

The output is (BEFORE press the button):

status = 0

The output is (AFTER press the button):

level: 0

status = 1

The FIFO seems full (i_status = 1) in the first press and in the first time when I check the "interrupted" flag. How can it occurs? NIOS is running a 100MHz. Is it slow for this application?

Thanks