xref: /freebsd/contrib/ofed/opensm/include/complib/cl_packon.h (revision 87181516ef48be852d5e5fee53c6e0dbfc62f21e)
1 /*
2  * Copyright (c) 2004, 2005 Voltaire, Inc. All rights reserved.
3  * Copyright (c) 2002-2005 Mellanox Technologies LTD. All rights reserved.
4  * Copyright (c) 1996-2003 Intel Corporation. All rights reserved.
5  *
6  * This software is available to you under a choice of one of two
7  * licenses.  You may choose to be licensed under the terms of the GNU
8  * General Public License (GPL) Version 2, available from the file
9  * COPYING in the main directory of this source tree, or the
10  * OpenIB.org BSD license below:
11  *
12  *     Redistribution and use in source and binary forms, with or
13  *     without modification, are permitted provided that the following
14  *     conditions are met:
15  *
16  *      - Redistributions of source code must retain the above
17  *        copyright notice, this list of conditions and the following
18  *        disclaimer.
19  *
20  *      - Redistributions in binary form must reproduce the above
21  *        copyright notice, this list of conditions and the following
22  *        disclaimer in the documentation and/or other materials
23  *        provided with the distribution.
24  *
25  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
26  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
27  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
28  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
29  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
30  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
31  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
32  * SOFTWARE.
33  *
34  */
35 
36 /*
37  * Abstract:
38  *  Turns on byte packing, which is necessary for passing information from
39  *	system to system over a network to ensure no padding by the compiler has
40  *	taken place.
41  */
42 
43 /****h* Component Library/Structure Packing
44 * NAME
45 *	Structure Packing
46 *
47 * DESCRIPTION
48 *	The structure packing header files allow packing structures on byte
49 *	boundaries.
50 *
51 *	Structure packing should be used whenever a structure is transmitted
52 *	between systems, as different platforms pad structures differently if
53 *	they are not packed.  Packing a structure that is not transmitted between
54 *	systems can be detrimental to performance, as fields in the structure may
55 *	not align properly for some platforms. Care must be taken when creating
56 *	packed structures that the alignment rules for all platforms are followed.
57 *
58 *	To pack a structure, include cl_packon.h before defining the structure, and
59 *	include cl_packoff.h after the structure definition.  Multiple structures
60 *	can be packed between the two include statements if desired.
61 *
62 *	The structure definition itself must use the PACK_SUFFIX keyword.
63 *
64 * EXAMPLE
65 *	#include <complib/cl_packon.h>
66 *
67 *	typedef _my_struct_t
68 *	{
69 *	    uint64 large;
70 *	    uint32 medium;
71 *	    uint16 small;
72 *
73 *	} PACK_SUFFIX my_struct_t;
74 *	#include <complib/cl_packoff.h>
75 *********/
76 
77 #ifndef PACK_SUFFIX
78 #define PACK_SUFFIX __attribute__((packed))
79 #endif
80 
81 #ifdef _MSC_VER
82 #pragma pack (push, 1)
83 #endif
84