char DeCharQ(char_q_t *p) // return 0/null if queue is empty
{
char ch;
if(CharEmptyQ(p))
{
cons_printf("Char queue is empty, can't dequeue!\n");
return 0; // return null char instead of -1 since the return type is char
}
ch = p->q[p->head];
p->head++;
if(p->head == CHAR_Q_SIZE) p->head = 0; // wrap
p->count--;
return ch;
}
char CharDeQ(char_q_t *p) // return -1 if queue is empty
{
char id;
if(CharEmptyQ(p))
{
cons_printf("Queue is empty, can't dequeue!\n");
return -1;
}
id = p->q[p->head];
p->head++;
if(p->head == Q_SIZE) p->head = 0; // wrap around
p->count--;
return id;
}
//
// remove char from out_q and send it out via UART
//
void IRQ34ISROutChar(int term_num)
{
char ch;
terminals[term_num].missed_intr = FALSE;
if(CharEmptyQ(&terminals[term_num].out_q) /*&&
CharEmptyQ(&terminals[term_num].echo_q)*/)
{
// nothing to display but the xmitter is ready, missed a chance to send a char
terminals[term_num].missed_intr = TRUE; // set it so can use output later
return; // nothing more to do more
}
ch = DeCharQ(&terminals[term_num].out_q); // get a char from out queue
//printf("\nch <= %c",ch);
outportb(terminals[term_num].io_base + DATA, ch); // output ch to UART
SemPostISR(terminals[term_num].out_sid); // post a space (char)
}
char CharDeQ(char_q_t *p) // return -1 if q is empty
{
char result;
if (CharEmptyQ(p)) {
cons_printf("Queue is empty, can't dequeue!\n");
return -1;
}
result = p->q[p->head];
p->head += 1;
if (p->head >= Q_SIZE) {
p->head = 0;
}
p->count -= 1;
return result;
}