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-rw-r--r--arch/v850/lib/checksum.c154
1 files changed, 154 insertions, 0 deletions
diff --git a/arch/v850/lib/checksum.c b/arch/v850/lib/checksum.c
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1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * MIPS specific IP/TCP/UDP checksumming routines
7 *
8 * Authors: Ralf Baechle, <ralf@waldorf-gmbh.de>
9 * Lots of code moved from tcp.c and ip.c; see those files
10 * for more names.
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version
15 * 2 of the License, or (at your option) any later version.
16 *
17 * $Id: checksum.c,v 1.1 2002/09/28 14:58:40 gerg Exp $
18 */
19#include <net/checksum.h>
20#include <linux/module.h>
21#include <linux/types.h>
22#include <asm/byteorder.h>
23#include <asm/string.h>
24#include <asm/uaccess.h>
25
26static inline unsigned short from32to16 (unsigned long sum)
27{
28 unsigned int result;
29 /*
30 %0 %1
31 hsw %1, %0 H L L H
32 add %1, %0 H L H+L+C H+L
33 */
34 asm ("hsw %1, %0; add %1, %0" : "=&r" (result) : "r" (sum));
35 return result >> 16;
36}
37
38static inline unsigned int do_csum(const unsigned char * buff, int len)
39{
40 int odd, count;
41 unsigned int result = 0;
42
43 if (len <= 0)
44 goto out;
45 odd = 1 & (unsigned long) buff;
46 if (odd) {
47 result = be16_to_cpu(*buff);
48 len--;
49 buff++;
50 }
51 count = len >> 1; /* nr of 16-bit words.. */
52 if (count) {
53 if (2 & (unsigned long) buff) {
54 result += *(unsigned short *) buff;
55 count--;
56 len -= 2;
57 buff += 2;
58 }
59 count >>= 1; /* nr of 32-bit words.. */
60 if (count) {
61 unsigned int carry = 0;
62 do {
63 unsigned int w = *(unsigned int *) buff;
64 count--;
65 buff += 4;
66 result += carry;
67 result += w;
68 carry = (w > result);
69 } while (count);
70 result += carry;
71 result = (result & 0xffff) + (result >> 16);
72 }
73 if (len & 2) {
74 result += *(unsigned short *) buff;
75 buff += 2;
76 }
77 }
78 if (len & 1)
79 result += le16_to_cpu(*buff);
80 result = from32to16(result);
81 if (odd)
82 result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
83out:
84 return result;
85}
86
87/*
88 * This is a version of ip_compute_csum() optimized for IP headers,
89 * which always checksum on 4 octet boundaries.
90 */
91unsigned short ip_fast_csum(unsigned char * iph, unsigned int ihl)
92{
93 return ~do_csum(iph,ihl*4);
94}
95
96/*
97 * this routine is used for miscellaneous IP-like checksums, mainly
98 * in icmp.c
99 */
100unsigned short ip_compute_csum(const unsigned char * buff, int len)
101{
102 return ~do_csum(buff,len);
103}
104
105/*
106 * computes a partial checksum, e.g. for TCP/UDP fragments
107 */
108unsigned int csum_partial(const unsigned char *buff, int len, unsigned int sum)
109{
110 unsigned int result = do_csum(buff, len);
111
112 /* add in old sum, and carry.. */
113 result += sum;
114 if(sum > result)
115 result += 1;
116 return result;
117}
118
119EXPORT_SYMBOL(csum_partial);
120
121/*
122 * copy while checksumming, otherwise like csum_partial
123 */
124unsigned int csum_partial_copy(const unsigned char *src, unsigned char *dst,
125 int len, unsigned int sum)
126{
127 /*
128 * It's 2:30 am and I don't feel like doing it real ...
129 * This is lots slower than the real thing (tm)
130 */
131 sum = csum_partial(src, len, sum);
132 memcpy(dst, src, len);
133
134 return sum;
135}
136
137/*
138 * Copy from userspace and compute checksum. If we catch an exception
139 * then zero the rest of the buffer.
140 */
141unsigned int csum_partial_copy_from_user (const unsigned char *src, unsigned char *dst,
142 int len, unsigned int sum,
143 int *err_ptr)
144{
145 int missing;
146
147 missing = copy_from_user(dst, src, len);
148 if (missing) {
149 memset(dst + len - missing, 0, missing);
150 *err_ptr = -EFAULT;
151 }
152
153 return csum_partial(dst, len, sum);
154}