about interrupt

I use nios2 .And I build a system with a on-chip ram and a key . I want to servise an interrupt from the key.

the following is my code:# include "system.h"# include "altera_avalon_pio_regs.h"# include "alt_types.h"# include "altera_avalon_uart_regs.h"# include "sys/alt_irq.h"

volatile int edge_capture;

static void handle_key_interrupt(void* context,alt_u32 id)

{

// int* edge_capture_ptr=(int*)context;

// IOWR_ALTERA_AVALON_PIO_EDGE_CAP(KEY_PIO_BASE);

IOWR_ALTERA_AVALON_PIO_IRQ_MASK(KEY_PIO_BASE, 0xf);

IOWR_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE, 0x55);

}

static void init_key_pio()

{

/* Recast the edge_capture pointer to match the alt_irq_register() function

* prototype. */

void* edge_capture_ptr = (void*) &edge_capture;

/* Enable all 4 button interrupts. */

IOWR_ALTERA_AVALON_PIO_IRQ_MASK(KEY_PIO_BASE, 0x1);

/* Reset the edge capture register. */

IOWR_ALTERA_AVALON_PIO_EDGE_CAP(KEY_PIO_BASE, 0x0);

/* Register the interrupt handler. */

alt_irq_register( KEY_PIO_IRQ, edge_capture_ptr, handle_key_interrupt );

}

int main (void) __attribute__ ((weak, alias ("alt_main")));

int alt_main (void)

{

volatile int i;

i=0;

// alt_u8 led=0x01;

// alt_u8 key;

# ifdef KEY_PIO_BASE

init_key_pio();# endif

i=alt_irq_enabled();

IOWR_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE, 0xf0);

while (1)

{

}

return 0;

}