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Bryan Wu1394f032007-05-06 14:50:22 -07001/*
2 * File: arch/blackfin/lib/checksum.c
3 * Based on: none - original work
4 * Author:
5 *
6 * Created:
7 * Description: An implementation of the TCP/IP protocol suite for the LINUX
8 * operating system. INET is implemented using the BSD Socket
9 * interface as the means of communication with the user level.
10 *
11 * Modified:
12 * Copyright 2004-2006 Analog Devices Inc.
13 *
14 * Bugs: Enter bugs at http://blackfin.uclinux.org/
15 *
16 * This program is free software; you can redistribute it and/or modify
17 * it under the terms of the GNU General Public License as published by
18 * the Free Software Foundation; either version 2 of the License, or
19 * (at your option) any later version.
20 *
21 * This program is distributed in the hope that it will be useful,
22 * but WITHOUT ANY WARRANTY; without even the implied warranty of
23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
24 * GNU General Public License for more details.
25 *
26 * You should have received a copy of the GNU General Public License
27 * along with this program; if not, see the file COPYING, or write
28 * to the Free Software Foundation, Inc.,
29 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
30 */
31
Mike Frysingerfe8015c2008-10-28 11:07:15 +080032#include <linux/module.h>
Bryan Wu1394f032007-05-06 14:50:22 -070033#include <net/checksum.h>
34#include <asm/checksum.h>
35
36#ifdef CONFIG_IP_CHECKSUM_L1
37static unsigned short do_csum(const unsigned char *buff, int len)__attribute__((l1_text));
38#endif
39
40static unsigned short do_csum(const unsigned char *buff, int len)
41{
42 register unsigned long sum = 0;
43 int swappem = 0;
44
45 if (1 & (unsigned long)buff) {
46 sum = *buff << 8;
47 buff++;
48 len--;
49 ++swappem;
50 }
51
52 while (len > 1) {
53 sum += *(unsigned short *)buff;
54 buff += 2;
55 len -= 2;
56 }
57
58 if (len > 0)
59 sum += *buff;
60
61 /* Fold 32-bit sum to 16 bits */
62 while (sum >> 16)
63 sum = (sum & 0xffff) + (sum >> 16);
64
65 if (swappem)
66 sum = ((sum & 0xff00) >> 8) + ((sum & 0x00ff) << 8);
67
68 return sum;
69
70}
71
72/*
73 * This is a version of ip_compute_csum() optimized for IP headers,
74 * which always checksum on 4 octet boundaries.
75 */
Al Viro45b39472008-05-12 11:55:10 +080076__sum16 ip_fast_csum(unsigned char *iph, unsigned int ihl)
Bryan Wu1394f032007-05-06 14:50:22 -070077{
Al Viro45b39472008-05-12 11:55:10 +080078 return (__force __sum16)~do_csum(iph, ihl * 4);
Bryan Wu1394f032007-05-06 14:50:22 -070079}
Mike Frysingerfe8015c2008-10-28 11:07:15 +080080EXPORT_SYMBOL(ip_fast_csum);
Bryan Wu1394f032007-05-06 14:50:22 -070081
82/*
83 * computes the checksum of a memory block at buff, length len,
84 * and adds in "sum" (32-bit)
85 *
86 * returns a 32-bit number suitable for feeding into itself
87 * or csum_tcpudp_magic
88 *
89 * this function must be called with even lengths, except
90 * for the last fragment, which may be odd
91 *
92 * it's best to have buff aligned on a 32-bit boundary
93 */
Al Viro45b39472008-05-12 11:55:10 +080094__wsum csum_partial(const void *buff, int len, __wsum sum)
Bryan Wu1394f032007-05-06 14:50:22 -070095{
96 /*
97 * Just in case we get nasty checksum data...
98 * Like 0xffff6ec3 in the case of our IPv6 multicast header.
99 * We fold to begin with, as well as at the end.
100 */
101 sum = (sum & 0xffff) + (sum >> 16);
102
103 sum += do_csum(buff, len);
104
105 sum = (sum & 0xffff) + (sum >> 16);
106
107 return sum;
108}
Mike Frysingerfe8015c2008-10-28 11:07:15 +0800109EXPORT_SYMBOL(csum_partial);
Bryan Wu1394f032007-05-06 14:50:22 -0700110
111/*
112 * this routine is used for miscellaneous IP-like checksums, mainly
113 * in icmp.c
114 */
Al Viro45b39472008-05-12 11:55:10 +0800115__sum16 ip_compute_csum(const void *buff, int len)
Bryan Wu1394f032007-05-06 14:50:22 -0700116{
Al Viro45b39472008-05-12 11:55:10 +0800117 return (__force __sum16)~do_csum(buff, len);
Bryan Wu1394f032007-05-06 14:50:22 -0700118}
119
120/*
121 * copy from fs while checksumming, otherwise like csum_partial
122 */
123
Al Viro45b39472008-05-12 11:55:10 +0800124__wsum
125csum_partial_copy_from_user(const void __user *src, void *dst,
126 int len, __wsum sum, int *csum_err)
Bryan Wu1394f032007-05-06 14:50:22 -0700127{
128 if (csum_err)
129 *csum_err = 0;
Al Viro45b39472008-05-12 11:55:10 +0800130 memcpy(dst, (__force void *)src, len);
Bryan Wu1394f032007-05-06 14:50:22 -0700131 return csum_partial(dst, len, sum);
132}
133
134/*
135 * copy from ds while checksumming, otherwise like csum_partial
136 */
137
Al Viro45b39472008-05-12 11:55:10 +0800138__wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum)
Bryan Wu1394f032007-05-06 14:50:22 -0700139{
140 memcpy(dst, src, len);
141 return csum_partial(dst, len, sum);
142}
Mike Frysingerfe8015c2008-10-28 11:07:15 +0800143EXPORT_SYMBOL(csum_partial_copy);