ttyputc.c

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/* ttyputc.c - ttyputc */

#include <xinu.h>

/*------------------------------------------------------------------------
 *  ttyputc  -  Write one character to a tty device (interrupts disabled)
 *------------------------------------------------------------------------
 */
devcall ttyputc(
    struct  dentry  *devptr,    /* Entry in device switch table */
    char    ch          /* Character to write       */
    )
{
    struct  ttycblk *typtr;     /* Pointer to tty control block */

    typtr = &ttytab[devptr->dvminor];

    /* Handle output CRLF by sending CR first */

        if ( ch==TY_NEWLINE && typtr->tyocrlf ) {
                ttyputc(devptr, TY_RETURN);
    }

    wait(typtr->tyosem);        /* Wait for space in queue */
    *typtr->tyotail++ = ch;

    /* Wrap around to beginning of buffer, if needed */

    if (typtr->tyotail >= &typtr->tyobuff[TY_OBUFLEN]) {
        typtr->tyotail = typtr->tyobuff;
    }

    /* Start output in case device is idle */

    ttykickout((struct uart_csreg *)devptr->dvcsr);

    return OK;
}