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/*
 * Copyright (c) 1982, 1986, 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.
 *
 *      @(#)mbuf.h      8.3 (Berkeley) 1/21/94
 * mbuf.h,v 1.9 1994/11/14 13:54:20 bde Exp
 */


#ifndef _MBUF_H_
#define _MBUF_H_

#define m_freem m_free


#define MINCSIZE 4096   /* Amount to increase mbuf if too small */

/*
 * Macros for type conversion
 * mtod(m,t) -  convert mbuf pointer to data pointer of correct type
 */

#define mtod(m,t)       ((t)(m)->m_data)

/* XXX About mbufs for slirp:
 * Only one mbuf is ever used in a chain, for each "cell" of data.
 * m_nextpkt points to the next packet, if fragmented.
 * If the data is too large, the M_EXT is used, and a larger block
 * is alloced.  Therefore, m_free[m] must check for M_EXT and if set
 * free the m_ext.  This is inefficient memory-wise, but who cares.
 */


/* XXX should union some of these! */
/* header at beginning of each mbuf: */
struct m_hdr {
        struct  mbuf *mh_next;          /* Linked list of mbufs */
        struct  mbuf *mh_prev;
        struct  mbuf *mh_nextpkt;       /* Next packet in queue/record */
        struct  mbuf *mh_prevpkt; /* Flags aren't used in the output queue */
        int     mh_flags;         /* Misc flags */

        int     mh_size;                /* Size of data */
        struct  socket *mh_so;

        caddr_t mh_data;                /* Location of data */
        int     mh_len;                 /* Amount of data in this mbuf */
};

/*
 * How much room is in the mbuf, from m_data to the end of the mbuf
 */

#define M_ROOM(m) ((m->m_flags & M_EXT)? \
                        (((m)->m_ext + (m)->m_size) - (m)->m_data) \
                   : \
                        (((m)->m_dat + (m)->m_size) - (m)->m_data))


/*
 * How much free room there is
 */

#define M_FREEROOM(m) (M_ROOM(m) - (m)->m_len)
#define M_TRAILINGSPACE M_FREEROOM

struct mbuf {
        struct  m_hdr m_hdr;
        Slirp *slirp;
        union M_dat {
                char    m_dat_[1]; /* ANSI don't like 0 sized arrays */
                char    *m_ext_;
        } M_dat;
};

#define m_next          m_hdr.mh_next
#define m_prev          m_hdr.mh_prev
#define m_nextpkt       m_hdr.mh_nextpkt
#define m_prevpkt       m_hdr.mh_prevpkt
#define m_flags         m_hdr.mh_flags
#define m_len           m_hdr.mh_len
#define m_data          m_hdr.mh_data
#define m_size          m_hdr.mh_size
#define m_dat           M_dat.m_dat_
#define m_ext           M_dat.m_ext_
#define m_so            m_hdr.mh_so

#define ifq_prev m_prev
#define ifq_next m_next
#define ifs_prev m_prevpkt
#define ifs_next m_nextpkt
#define ifq_so m_so

#define M_EXT                   0x01    /* m_ext points to more (malloced) data */
#define M_FREELIST              0x02    /* mbuf is on free list */
#define M_USEDLIST              0x04    /* XXX mbuf is on used list (for dtom()) */
#define M_DOFREE                0x08    /* when m_free is called on the mbuf, free()
                                         * it rather than putting it on the free list */

void m_init(Slirp *);
struct mbuf * m_get(Slirp *);
void m_free(struct mbuf *);
void m_cat(register struct mbuf *, register struct mbuf *);
void m_inc(struct mbuf *, int);
void m_adj(struct mbuf *, int);
int m_copy(struct mbuf *, struct mbuf *, int, int);
struct mbuf * dtom(Slirp *, void *);

#endif