source: trunk/minix/lib/stdio/ungetc.c@ 20

/*
 * ungetc.c - push a character back onto an input stream
 */
/* $Header: /cvsup/minix/src/lib/stdio/ungetc.c,v 1.1.1.1 2005/04/21 14:56:36 beng Exp $ */

#include        <stdio.h>
#include        "loc_incl.h"

int
ungetc(int ch, FILE *stream)
{
        unsigned char *p;

        if (ch == EOF  || !io_testflag(stream,_IOREADING))
                return EOF;
        if (stream->_ptr == stream->_buf) {
                if (stream->_count != 0) return EOF;
                stream->_ptr++;
        }
        stream->_count++;
        p = --(stream->_ptr);           /* ??? Bloody vax assembler !!! */
        /* ungetc() in sscanf() shouldn't write in rom */
        if (*p != (unsigned char) ch)
                *p = (unsigned char) ch;
        return ch;
}