/* kprintf.c -  kputc, kgetc, kprintf */

#include 
#include 

/*------------------------------------------------------------------------
 * kputc  -  use polled I/O to write a character to the console
 *------------------------------------------------------------------------
 */
syscall kputc(
          byte  c                       /* character to write           */
        )
{
        struct  dentry  *devptr;
        volatile struct uart_csreg *csrptr;
        intmask mask;

        /* Disable interrupts */
        mask = disable();

        /* Get CSR address of the console */

        devptr = (struct dentry *) &devtab[CONSOLE];
        csrptr = (struct uart_csreg *)devptr->dvcsr;

        /* Fail if no console device was found */

        if (csrptr == NULL) {
                restore(mask);
                return SYSERR;
        }

        /* Repeatedly poll the device until it becomes nonbusy */

        while ( (csrptr->lsr & UART_LSR_THRE) == 0 ) {
                ;
        }

        /* Write the character */

        csrptr->buffer = c;

        /* Honor CRLF - when writing NEWLINE also send CARRIAGE RETURN  */

        if (c == '\n') {
                /* Poll until transmitter queue is empty */
                while ( (csrptr->lsr & UART_LSR_THRE) == 0 ) {
                        ;
                }
                csrptr->buffer = '\r';
        }

        restore(mask);
        return OK;
}

/*------------------------------------------------------------------------
 * kgetc - use polled I/O to read a character from the console serial line
 *------------------------------------------------------------------------
 */
syscall kgetc(void)
{
        int irmask;
        volatile struct uart_csreg *csrptr;
        byte c;
        struct  dentry  *devptr;
        intmask mask;

        /* Disable interrupts */
        mask = disable();

        devptr = (struct dentry *) &devtab[CONSOLE];
        csrptr = (struct uart_csreg *)devptr->dvcsr;

        /* Fail if no console device was found */
        if (csrptr == NULL) {
                restore(mask);
                return SYSERR;
        }

        irmask = csrptr->ier;           /* Save UART interrupt state.   */
        csrptr->ier = 0;                /* Disable UART interrupts.     */

        /* wait for UART transmit queue to empty */

        while (0 == (csrptr->lsr & UART_LSR_DR)) {
                ; /* Do Nothing */
        }

        /* Read character from Receive Holding Register */

        c = csrptr->rbr;
        csrptr->ier = irmask;           /* Restore UART interrupts.     */

        restore(mask);
        return c;
}

extern  void    _doprnt(char *, va_list, int (*)(int));

/*------------------------------------------------------------------------
 * kprintf  -  use polled I/O to print formatted output on the console
 *------------------------------------------------------------------------
 */
syscall kprintf(char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        _doprnt(fmt, ap, (int (*)(int))kputc);
        va_end(ap);
        return OK;
}