/*      $OpenBSD: ring.h,v 1.9 2014/07/20 08:12:46 guenther Exp $       */
/*      $NetBSD: ring.h,v 1.5 1996/02/28 21:04:09 thorpej Exp $ */

/*
 * Copyright (c) 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      from: @(#)ring.h        8.1 (Berkeley) 6/6/93
 */

/*
 * This defines a structure for a ring buffer.
 *
 * The circular buffer has two parts:
 *(((
 *      full:   [consume, supply)
 *      empty:  [supply, consume)
 *]]]
 *
 */
typedef struct {
        unsigned char   *consume;       /* where data comes out of */
        unsigned char   *supply;        /* where data comes in to */
        unsigned char   *bottom;        /* lowest address in buffer */
        unsigned char   *top;           /* highest address+1 in buffer */
        unsigned char   *mark;          /* marker (user defined) */
        int             size;           /* size in bytes of buffer */
        unsigned long   consumetime;    /* help us keep straight full, empty, etc. */
        unsigned long   supplytime;
} Ring;

/* Here are some functions and macros to deal with the ring buffer */

/* Initialization routine */
void    ring_init(Ring *ring, unsigned char *buffer, int size);

/* Data movement routines */
void    ring_supply_data(Ring *ring, unsigned char *buffer, int count);

/* Buffer state transition routines */
void    ring_supplied(Ring *ring, int count);
void    ring_consumed(Ring *ring, int count);

/* Buffer state query routines */
int     ring_empty_count(Ring *ring);
int     ring_empty_consecutive(Ring *ring);
int     ring_full_count(Ring *ring);
int     ring_full_consecutive(Ring *ring);

/* Buffer urgent data handling */
void    ring_clear_mark(Ring *);
void    ring_mark(Ring *);
int     ring_at_mark(Ring *);