mbuf.h

/*
 * 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
 * dtom(x) -	convert data pointer within mbuf to mbuf pointer (XXX)
 */
#define mtod(m, t) ((t)(m)->m_data)
/* #define	dtom(x)		((struct mbuf *)((int)(x) & ~(M_SIZE-1))) */

/* 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;
    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 */

/*
 * Mbuf statistics. XXX
 */

struct mbstat {
    int mbs_alloced; /* Number of mbufs allocated */
};

extern struct mbstat mbstat;
extern int mbuf_alloced;
extern struct mbuf m_freelist, m_usedlist;
extern int mbuf_max;

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

#endif