1 /* $Id$ */
2 /*
3  * Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
4  * Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
19  */
20 #ifndef __PJLIB_UTIL_CRC32_H__
21 #define __PJLIB_UTIL_CRC32_H__
22 
23 /**
24  * @file crc32.h
25  * @brief CRC32 implementation
26  */
27 
28 #include <pjlib-util/types.h>
29 
30 PJ_BEGIN_DECL
31 
32 /**
33  * @defgroup PJLIB_UTIL_CRC32 CRC32 (Cyclic Redundancy Check)
34  * @ingroup PJLIB_UTIL_ENCRYPTION
35  * @{
36  * This implements CRC32 algorithm. See ITU-T V.42 for the formal
37  * specification.
38  */
39 
40 /** CRC32 context. */
41 typedef struct pj_crc32_context
42 {
43     pj_uint32_t	crc_state;	/**< Current state. */
44 } pj_crc32_context;
45 
46 
47 /**
48  * Initialize CRC32 context.
49  *
50  * @param ctx	    CRC32 context.
51  */
52 PJ_DECL(void) pj_crc32_init(pj_crc32_context *ctx);
53 
54 /**
55  * Feed data incrementally to the CRC32 algorithm.
56  *
57  * @param ctx	    CRC32 context.
58  * @param data	    Input data.
59  * @param nbytes    Length of the input data.
60  *
61  * @return	    The current CRC32 value.
62  */
63 PJ_DECL(pj_uint32_t) pj_crc32_update(pj_crc32_context *ctx,
64 				     const pj_uint8_t *data,
65 				     pj_size_t nbytes);
66 
67 /**
68  * Finalize CRC32 calculation and retrieve the CRC32 value.
69  *
70  * @param ctx	    CRC32 context.
71  *
72  * @return	    The current CRC value.
73  */
74 PJ_DECL(pj_uint32_t) pj_crc32_final(pj_crc32_context *ctx);
75 
76 /**
77  * Perform one-off CRC32 calculation to the specified data.
78  *
79  * @param data	    Input data.
80  * @param nbytes    Length of input data.
81  *
82  * @return	    CRC value of the data.
83  */
84 PJ_DECL(pj_uint32_t) pj_crc32_calc(const pj_uint8_t *data,
85 				   pj_size_t nbytes);
86 
87 
88 /**
89  * @}
90  */
91 
92 PJ_END_DECL
93 
94 
95 #endif	/* __PJLIB_UTIL_CRC32_H__ */
96 
97