FreeBSD/Linux Kernel Cross Reference
sys/net/netmap_user.h

     /*
      * Copyright (C) 2011 Matteo Landi, Luigi Rizzo. 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 authors nor the names of their contributors
     *      may be used to endorse or promote products derived from this
     *      software without specific prior written permission.
     * 
     * THIS SOFTWARE IS PROVIDED BY MATTEO LANDI 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 MATTEO LANDI 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.
     */
    
    /*
     * $FreeBSD: releng/8.4/sys/net/netmap_user.h 231717 2012-02-14 22:49:34Z luigi $
     * $Id: netmap_user.h 9495 2011-10-18 15:28:23Z luigi $
     *
     * This header contains the macros used to manipulate netmap structures
     * and packets in userspace. See netmap(4) for more information.
     *
     * The address of the struct netmap_if, say nifp, is determined
     * by the value returned from ioctl(.., NIOCREG, ...) and the mmap
     * region:
     *      ioctl(fd, NIOCREG, &req);
     *      mem = mmap(0, ... );
     *      nifp = NETMAP_IF(mem, req.nr_nifp);
     *              (so simple, we could just do it manually)
     *
     * From there:
     *      struct netmap_ring *NETMAP_TXRING(nifp, index)
     *      struct netmap_ring *NETMAP_RXRING(nifp, index)
     *              we can access ring->nr_cur, ring->nr_avail, ring->nr_flags
     *
     *      ring->slot[i] gives us the i-th slot (we can access
     *              directly plen, flags, bufindex)
     *
     *      char *buf = NETMAP_BUF(ring, index) returns a pointer to
     *              the i-th buffer
     *
     * Since rings are circular, we have macros to compute the next index
     *      i = NETMAP_RING_NEXT(ring, i);
     */
    
    #ifndef _NET_NETMAP_USER_H_
    #define _NET_NETMAP_USER_H_
    
    #define NETMAP_IF(b, o) (struct netmap_if *)((char *)(b) + (o))
    
    #define NETMAP_TXRING(nifp, index)                      \
            ((struct netmap_ring *)((char *)(nifp) +        \
                    (nifp)->ring_ofs[index] ) )
    
    #define NETMAP_RXRING(nifp, index)                      \
            ((struct netmap_ring *)((char *)(nifp) +        \
                (nifp)->ring_ofs[index + (nifp)->ni_num_queues+1] ) )
    
    #define NETMAP_BUF(ring, index)                         \
            ((char *)(ring) + (ring)->buf_ofs + ((index)*(ring)->nr_buf_size))
    
    #define NETMAP_RING_NEXT(r, i)                          \
            ((i)+1 == (r)->num_slots ? 0 : (i) + 1 )
    
    /*
     * Return 1 if the given tx ring is empty.
     *
     * @r netmap_ring descriptor pointer.
     * Special case, a negative value in hwavail indicates that the
     * transmit queue is idle.
     * XXX revise
     */
    #define NETMAP_TX_RING_EMPTY(r) ((r)->avail >= (r)->num_slots - 1)
    
    #endif /* _NET_NETMAP_USER_H_ */

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