/*
**  FREEBUF.C -- more routines for LIFO dynamic buffer allocation [need.c]
**
**	These routines allow the deallocation of a need() type buffer,
**	and also using the same buffer for various SERIALIZED purposes
**	by marking the end of one, beginning of the next.
**
**	Defines:
**		freebuf()
**		markbuf()
**		seterr()
**
**	Requires:
**		that the buffer structure be IDENTICAL to that in [need.c]
**
**	History:
**		10/12/78 -- (marc) separated from [need.c] so that processes
**			not using more that need() and initbuf() wouldn't load
**			it.
*/






/* structure that the routines use to allocate space */
struct nodbuffer
{
	int		nleft;		/* bytes left */
	int		err_num;	/* error code on overflow */
	int		(*err_func)();	/* error function on overflow */
	char		*xfree;		/* next free byte */
	char		buffer [];	/*beginning of buffer area */
};

/*
**  MARKBUF -- Mark a place in the buffer to deallocate to
**
**	Parameters:
**		bf -- buffer
**
**	Returns:
**		int >= 0 marking place in buffer (should be used in calling
**			freebuf())
**
**	Side Effects:
**		none
*/

markbuf(bf)
struct nodbuffer	*bf;
{
	register struct nodbuffer	*buf;

	buf = bf;
	return (buf->nleft);
}


/*
**  FREEBUF -- frees part of a buffer
**
**	Parameters:
**		bf -- buffer
**		bytes -- a previous return from markbuf().
**
**	Returns:
**		none
**
**	Side Effects:
**		none
*/

freebuf(bf, bytes)
struct nodbuffer	*bf;
int			bytes;
{
	register struct nodbuffer	*buf;
	register int			i;

	buf = bf;
	i = bytes - buf->nleft;
	if (i < 0)
		syserr("freebuf %d, %d", i, bytes);
	buf->xfree -= i;
	buf->nleft += i;
}

/*
**  SETERR -- change the error info for a buffer
**
**	Parameters:
**		bf -- buffer
**		errnum -- new overflow error code
**		err_func -- new error handler
**
**	Returns:
**		none
**
**	Side Effects:
**		adjusts buffer structure
*/

seterr(bf, errnum, err_func)
struct nodbuffer	*bf;
int			errnum;
int			(*err_func)();
{
	register struct nodbuffer	*buf;
	register int			(*erf)();

	buf = bf;
	erf = err_func;
	buf->err_num = errnum;
	bf->err_func = erf;
}