ttyread.c File Reference

#include <xinu.h>

Include dependency graph for ttyread.c:

Go to the source code of this file.

Functions
devcall	ttyread (struct dentry *devptr, char *buff, int32 count)

Function Documentation

ttyread()

devcall ttyread	(	struct dentry *	devptr,
		char *	buff,
		int32	count
	)

Definition at line 9 of file ttyread.c.

References dentry::dvminor, EOF, semcount(), SYSERR, ttygetc(), ttytab, TY_IMCOOKED, TY_NEWLINE, TY_RETURN, ttycblk::tyimode, and ttycblk::tyisem.

{
    struct  ttycblk *typtr;     /* Pointer to tty control block */
    int32   avail;          /* Characters available in buff.*/
    int32   nread;          /* Number of characters read    */
    int32   firstch;        /* First input character on line*/
    char    ch;         /* Next input character     */

    if (count < 0) {
        return SYSERR;
    }
    typtr= &ttytab[devptr->dvminor];

    if (typtr->tyimode != TY_IMCOOKED) {

        /* For count of zero, return all available characters */

        if (count == 0) {
            avail = semcount(typtr->tyisem);
            if (avail == 0) {
                return 0;
            } else {
                count = avail;
            }
        }
        for (nread = 0; nread < count; nread++) {
            *buff++ = (char) ttygetc(devptr);
        }
        return nread;
    }

    /* Block until input arrives */

    firstch = ttygetc(devptr);

    /* Check for End-Of-File */

    if (firstch == EOF) {
        return EOF;
    }

    /* Read up to a line */

    ch = (char) firstch;
    *buff++ = ch;
    nread = 1;
    while ( (nread < count) && (ch != TY_NEWLINE) &&
            (ch != TY_RETURN) ) {
        ch = ttygetc(devptr);
        *buff++ = ch;
        nread++;
    }
    return nread;
}

Here is the call graph for this function: