minix/lib/stdio/ungetc.c
2009-11-09 10:26:00 +00:00

26 lines
541 B
C

/*
* ungetc.c - push a character back onto an input stream
*/
/* $Header$ */
#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;
}