/* ttyhandle_out.c - ttyhandle_out */

#include 

/*------------------------------------------------------------------------
 *  ttyhandle_out  -  Handle an output on a tty device by sending more
 *                   characters to the device FIFO (interrupts disabled)
 *------------------------------------------------------------------------
 */
void    ttyhandle_out(
         struct ttycblk *typtr,         /* Ptr to ttytab entry          */
         struct uart_csreg *csrptr      /* Address of UART's CSRs       */
        )
{
        
        int32   ochars;                 /* Number of output chars sent  */
                                        /*   to the UART                */
        int32   avail;                  /* Available chars in output buf*/
        int32   uspace;                 /* Space left in onboard UART   */
                                        /*   output FIFO                */
        byte    ier = 0;

        /* If output is currently held, simply ignore the call */

        if (typtr->tyoheld) {
                return;
        }

        /* If echo and output queues empty, turn off interrupts */

        if ( (typtr->tyehead == typtr->tyetail) &&
             (semcount(typtr->tyosem) >= TY_OBUFLEN) ) {
                ier = csrptr->ier;
                csrptr->ier = ier & ~UART_IER_ETBEI;
                return;
        }
        
        /* Initialize uspace to the size of the transmit FIFO */

        uspace = UART_FIFO_SIZE;

        /* While onboard FIFO is not full and the echo queue is */
        /*   nonempty, xmit chars from the echo queue           */

        while ( (uspace>0) &&  typtr->tyehead != typtr->tyetail) {
                csrptr->buffer = *typtr->tyehead++;
                if (typtr->tyehead >= &typtr->tyebuff[TY_EBUFLEN]) {
                        typtr->tyehead = typtr->tyebuff;
                }
                uspace--;
        }

        /* While onboard FIFO is not full and the output queue is       */
        /*   nonempty, transmit chars from the output queue             */

        ochars = 0;
        avail = TY_OBUFLEN - semcount(typtr->tyosem);
        if (avail > TY_OBUFLEN) {       /* In case semcount < 0 */
                avail = TY_OBUFLEN;
        }
        while ( (uspace>0) &&  (avail > 0) ) {
                csrptr->buffer = *typtr->tyohead++;
                if (typtr->tyohead >= &typtr->tyobuff[TY_OBUFLEN]) {
                        typtr->tyohead = typtr->tyobuff;
                }
                avail--;
                uspace--;
                ochars++;
        }
        if (ochars > 0) {
                signaln(typtr->tyosem, ochars);
        }
        return;
}