static int spi_read(struct bathos_pipe *pipe, char *buf, int len)
{
struct spi_data *data = &spi_data;
int flags;
int l;
interrupt_disable(flags);
l = min(len, CIRC_CNT_TO_END(data->cbufrx.head, data->cbufrx.tail,
SPI_BUF_SIZE));
if (!l) {
interrupt_restore(flags);
return -EAGAIN;
}
memcpy(buf, &data->bufrx[data->cbufrx.tail], l);
data->cbufrx.tail = (data->cbufrx.tail + l) & (SPI_BUF_SIZE - 1);
data->overrun = 0;
if (CIRC_CNT(data->cbufrx.head, data->cbufrx.tail, SPI_BUF_SIZE))
pipe_dev_trigger_event(&__spi_dev, &evt_pipe_input_ready,
EVT_PRIO_MAX);
interrupt_restore(flags);
return l;
}
void
sema_down (struct semaphore* sema)
{
ASSERT (sema != NULL);
enum interrupt_state state = interrupt_off ();
/* All accesses to this semaphore must be synchronized using the
semaphore's internal spinlock. */
spinlock_acquire (&sema->sync);
/* If the semaphore's value is at 0, then we must block the thread */
while (sema->val == 0)
{
list_push_back (&sema->waiters, &thread_current ()->elem);
// spinlock_release (&sema->sync);
thread_block ();
// spinlock_acquire (&sema->sync);
}
/* Decrement the semaphore's value */
sema->val--;
spinlock_release (&sema->sync);
interrupt_restore (state);
interrupt_on ();
};
void
sema_up (struct semaphore* sema)
{
ASSERT (sema != NULL);
enum interrupt_state state = interrupt_off ();
// spinlock_acquire (&sema->sync);
sema->val++;
struct thread* t = LIST_ENTRY (
list_pop_back (&sema->waiters), struct thread, elem);
// spinlock_release (&sema->sync);
thread_unblock (t);
interrupt_restore (state);
};
bool
sema_try_down (struct semaphore* sema)
{
bool result = true;
ASSERT (sema != NULL);
enum interrupt_state state = interrupt_off ();
// spinlock_acquire (&sema->sync);
result = (sema->val > 0);
if (result)
{
sema->val--;
}
// spinlock_release (&sema->sync);
interrupt_restore (state);
return result;
};
