getc.c

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/* getc.c - getc */

#include <xinu.h>

/*------------------------------------------------------------------------
 *  getc  -  Obtain one byte from a device
 *------------------------------------------------------------------------
 */
syscall getc(
      did32     descrp      /* Descriptor for device    */
    )
{
    intmask     mask;       /* Saved interrupt mask     */
    struct dentry   *devptr;    /* Entry in device switch table */
    int32       retval;     /* Value to return to caller    */

    mask = disable();
    if (isbaddev(descrp)) {
        restore(mask);
        return SYSERR;
    }
    devptr = (struct dentry *) &devtab[descrp];
    retval = (*devptr->dvgetc) (devptr);
    restore(mask);
    return retval;
}