netmap_user.h revision 241166 
1/*
2 * Copyright (C) 2011 Matteo Landi, Luigi Rizzo. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met:
7 *
8 *   1. Redistributions of source code must retain the above copyright
9 *      notice, this list of conditions and the following disclaimer.
10 *
11 *   2. Redistributions in binary form must reproduce the above copyright
12 *      notice, this list of conditions and the following disclaimer in the
13 *      documentation and/or other materials provided with the
14 *      distribution.
15 *
16 *   3. Neither the name of the authors nor the names of their contributors
17 *      may be used to endorse or promote products derived from this
18 *      software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY MATTEO LANDI AND CONTRIBUTORS "AS IS" AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTEO LANDI OR CONTRIBUTORS
24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
30 * THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33/*
34 * $FreeBSD: head/sys/net/netmap_user.h 241166 2012-10-03 21:41:20Z emaste $
35 * $Id: netmap_user.h 10597 2012-02-21 05:08:32Z luigi $
36 *
37 * This header contains the macros used to manipulate netmap structures
38 * and packets in userspace. See netmap(4) for more information.
39 *
40 * The address of the struct netmap_if, say nifp, is computed from the
41 * value returned from ioctl(.., NIOCREG, ...) and the mmap region:
42 *	ioctl(fd, NIOCREG, &req);
43 *	mem = mmap(0, ... );
44 *	nifp = NETMAP_IF(mem, req.nr_nifp);
45 *		(so simple, we could just do it manually)
46 *
47 * From there:
48 *	struct netmap_ring *NETMAP_TXRING(nifp, index)
49 *	struct netmap_ring *NETMAP_RXRING(nifp, index)
50 *		we can access ring->nr_cur, ring->nr_avail, ring->nr_flags
51 *
52 *	ring->slot[i] gives us the i-th slot (we can access
53 *		directly plen, flags, bufindex)
54 *
55 *	char *buf = NETMAP_BUF(ring, index) returns a pointer to
56 *		the i-th buffer
57 *
58 * Since rings are circular, we have macros to compute the next index
59 *	i = NETMAP_RING_NEXT(ring, i);
60 */
61
62#ifndef _NET_NETMAP_USER_H_
63#define _NET_NETMAP_USER_H_
64
65#define _NETMAP_OFFSET(type, ptr, offset) \
66	((type)(void *)((char *)(ptr) + (offset)))
67
68#define NETMAP_IF(b, o)	_NETMAP_OFFSET(struct netmap_if *, b, o)
69
70#define NETMAP_TXRING(nifp, index) _NETMAP_OFFSET(struct netmap_ring *, \
71	nifp, (nifp)->ring_ofs[index] )
72
73#define NETMAP_RXRING(nifp, index) _NETMAP_OFFSET(struct netmap_ring *,	\
74	nifp, (nifp)->ring_ofs[index + (nifp)->ni_tx_rings + 1] )
75
76#define NETMAP_BUF(ring, index)				\
77	((char *)(ring) + (ring)->buf_ofs + ((index)*(ring)->nr_buf_size))
78
79#define NETMAP_BUF_IDX(ring, buf)			\
80	( ((char *)(buf) - ((char *)(ring) + (ring)->buf_ofs) ) / \
81		(ring)->nr_buf_size )
82
83#define	NETMAP_RING_NEXT(r, i)				\
84	((i)+1 == (r)->num_slots ? 0 : (i) + 1 )
85
86#define	NETMAP_RING_FIRST_RESERVED(r)			\
87	( (r)->cur < (r)->reserved ?			\
88	  (r)->cur + (r)->num_slots - (r)->reserved :	\
89	  (r)->cur - (r)->reserved )
90
91/*
92 * Return 1 if the given tx ring is empty.
93 */
94#define NETMAP_TX_RING_EMPTY(r)	((r)->avail >= (r)->num_slots - 1)
95
96#endif /* _NET_NETMAP_USER_H_ */
97