ttygetc.c

Go to the documentation of this file.

/* ttygetc.c - ttygetc */

#include <xinu.h>

/*------------------------------------------------------------------------
 *  ttygetc  -  Read one character from a tty device (interrupts disabled)
 *------------------------------------------------------------------------
 */
devcall ttygetc(
      struct dentry *devptr     /* Entry in device switch table */
    )
{
    char    ch;         /* Character to return      */
    struct  ttycblk *typtr;     /* Pointer to ttytab entry  */

    typtr = &ttytab[devptr->dvminor];

    /* Wait for a character in the buffer and extract one character */

    wait(typtr->tyisem);
    ch = *typtr->tyihead++;

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

    if (typtr->tyihead >= &typtr->tyibuff[TY_IBUFLEN]) {
        typtr->tyihead = typtr->tyibuff;
    }

    /* In cooked mode, check for the EOF character */

    if ( (typtr->tyimode == TY_IMCOOKED) && (typtr->tyeof) &&
         (ch == typtr->tyeofch) ) {
        return (devcall)EOF;
    }

    return (devcall)ch;
}