void handle_usb(u32 clkn)
{
u8 epstat;
/* write queued packets to USB if possible */
epstat = USBHwEPGetStatus(BULK_IN_EP);
if (!(epstat & EPSTAT_B1FULL)) {
dequeue_send(clkn);
}
if (!(epstat & EPSTAT_B2FULL)) {
dequeue_send(clkn);
}
/* polled "interrupt" */
USBHwISR();
}
/* Send an IPC to another thread. */
NORETURN void
sys_ipc_recv(word_t src_thread, word_t operation)
{
/* Ensure the thread exists. */
if (EXPECT_FALSE(src_thread >= max_tcbs && src_thread != IPC_WAIT_ANY)) {
syscall_return_error(IPC_ERROR, EINVAL);
}
spin_lock(&ipc_lock);
/* Get first thread on send queue. */
tcb_t *src = current_tcb->ipc_send_head;
/* If there are no threads, go to sleep. */
if (src == NULL) {
current_tcb->ipc_waiting_for = src;
tcb_t *next = deactivate_self_schedule(THREAD_STATE_WAIT_IPC_RECV);
spin_unlock(&ipc_lock);
switch_to(next);
}
/* Otherwise, dequeue the thread. */
dequeue_send(current_tcb, src);
/* Copy the message across and wake up the sender. */
copy_message(src, current_tcb);
/* Is the sender performing a call? */
if (src->thread_state == THREAD_STATE_WAIT_IPC_CALL) {
/* Move it into receive phase. 'ipc_waiting_for' should already be set
* to us. */
word_t tid = src->tid;
ASSERT(src->ipc_waiting_for == current_tcb);
src->thread_state = THREAD_STATE_WAIT_IPC_RECV;
spin_unlock(&ipc_lock);
syscall_return_success(tid);
/* NOTREACHED */
}
/* If the sender was not performing a call, wake them up. */
src->ipc_waiting_for = NULL;
set_syscall_return_val_success(src, 0);
set_syscall_return_val_success(current_tcb, src->tid);
tcb_t *next = activate_schedule(src);
spin_unlock(&ipc_lock);
switch_to(next);
/* NOTREACHED */
}
