/**
* TTY's interrupt handler. Functinality depends on status of TTY's
* status port. On WIRQ status writes internal buffer from
* tty_real_device_t data structure to data port. On RIRQ
* status reads data from data port to the internal buffer.
* Implements read from the gbd interface.
*
* @param device Pointer to the TTY device.
*/
void tty_interrupt_handle(device_t *device) {
volatile tty_io_area_t *iobase = (tty_io_area_t *)device->io_address;
volatile tty_real_device_t *tty_rd
= (tty_real_device_t *)device->real_device;
if(TTY_STATUS_WIRQ(iobase->status)) {
spinlock_acquire(tty_rd->slock);
iobase->command = TTY_COMMAND_WIRQD;
iobase->command = TTY_COMMAND_WIRQ;
while(!TTY_STATUS_WBUSY(iobase->status) && tty_rd->write_count > 0) {
iobase->command = TTY_COMMAND_WIRQ;
iobase->data = tty_rd->write_buf[tty_rd->write_head];
tty_rd->write_head = (tty_rd->write_head + 1) % TTY_BUF_SIZE;
tty_rd->write_count--;
}
iobase->command = TTY_COMMAND_WIRQE;
if (tty_rd->write_count == 0)
sleepq_wake_all((void *)tty_rd->write_buf);
spinlock_release(tty_rd->slock);
}
if(TTY_STATUS_RIRQ(iobase->status)) {
spinlock_acquire(tty_rd->slock);
iobase->command = TTY_COMMAND_RIRQ;
if (TTY_STATUS_ERROR(iobase->status))
KERNEL_PANIC("Could not issue RIRQ to TTY.");
while (TTY_STATUS_RAVAIL(iobase->status)) {
char data = iobase->data;
int index;
if (tty_rd->read_count > TTY_BUF_SIZE)
continue;
index = (tty_rd->read_head + tty_rd->read_count) % TTY_BUF_SIZE;
tty_rd->read_buf[index] = data;
tty_rd->read_count++;
}
spinlock_release(tty_rd->slock);
sleepq_wake_all((void *)tty_rd->read_buf);
}
}
/**
* Gets one character from the TTY.
*
* @return The character read from the TTY. If the
* \texttt{polltty_iobase} is invalid, returns 0.
*
*/
int polltty_getchar()
{
/* Check that the iobase is valid */
if (polltty_iobase == 0)
return 0;
/* Wait until there is a character available */
while(TTY_STATUS_RAVAIL(polltty_iobase->status) == 0);
/* Clear interrupt */
polltty_iobase->command = TTY_COMMAND_RIRQ;
return polltty_iobase->data;
}