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add generic lib/checksum.c

Add a generic (unoptimized) implementation of checksum.c in pure C for use by all architectures that cannot be bother with implementing their own version. Based on microblaze code by Michal Simek <monstr@monstr.eu>

Arnd Bergmann committed 17 years ago

Commit 26a28fa1 parent eed417d3 files · +274 −0Browse files

Unified · Split

3 files
  1. include/asm-generic/checksum.h +79 −0
  2. lib/Makefile +2 −0
  3. lib/checksum.c +193 −0
include/asm-generic/checksum.h+79−0
@@ -0,0 +1,79 @@
1#ifndef __ASM_GENERIC_CHECKSUM_H
2#define __ASM_GENERIC_CHECKSUM_H
3
4/*
5 * computes the checksum of a memory block at buff, length len,
6 * and adds in "sum" (32-bit)
7 *
8 * returns a 32-bit number suitable for feeding into itself
9 * or csum_tcpudp_magic
10 *
11 * this function must be called with even lengths, except
12 * for the last fragment, which may be odd
13 *
14 * it's best to have buff aligned on a 32-bit boundary
15 */
16extern __wsum csum_partial(const void *buff, int len, __wsum sum);
17
18/*
19 * the same as csum_partial, but copies from src while it
20 * checksums
21 *
22 * here even more important to align src and dst on a 32-bit (or even
23 * better 64-bit) boundary
24 */
25extern __wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum);
26
27/*
28 * the same as csum_partial_copy, but copies from user space.
29 *
30 * here even more important to align src and dst on a 32-bit (or even
31 * better 64-bit) boundary
32 */
33extern __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
34 int len, __wsum sum, int *csum_err);
35
36#define csum_partial_copy_nocheck(src, dst, len, sum) \
37 csum_partial_copy((src), (dst), (len), (sum))
38
39/*
40 * This is a version of ip_compute_csum() optimized for IP headers,
41 * which always checksum on 4 octet boundaries.
42 */
43extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
44
45/*
46 * Fold a partial checksum
47 */
48static inline __sum16 csum_fold(__wsum csum)
49{
50 u32 sum = (__force u32)csum;
51 sum = (sum & 0xffff) + (sum >> 16);
52 sum = (sum & 0xffff) + (sum >> 16);
53 return (__force __sum16)~sum;
54}
55
56#ifndef csum_tcpudp_nofold
57/*
58 * computes the checksum of the TCP/UDP pseudo-header
59 * returns a 16-bit checksum, already complemented
60 */
61extern __wsum
62csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
63 unsigned short proto, __wsum sum);
64#endif
65
66static inline __sum16
67csum_tcpudp_magic(__be32 saddr, __be32 daddr, unsigned short len,
68 unsigned short proto, __wsum sum)
69{
70 return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
71}
72
73/*
74 * this routine is used for miscellaneous IP-like checksums, mainly
75 * in icmp.c
76 */
77extern __sum16 ip_compute_csum(const void *buff, int len);
78
79#endif /* __ASM_GENERIC_CHECKSUM_H */
lib/Makefile+2−0
@@ -92,6 +92,8 @@ obj-$(CONFIG_NLATTR) += nlattr.o · 91 unmodified lines
92 92
93obj-$(CONFIG_DMA_API_DEBUG) += dma-debug.o93obj-$(CONFIG_DMA_API_DEBUG) += dma-debug.o
94 94
95obj-$(CONFIG_GENERIC_CSUM) += checksum.o
96
95hostprogs-y := gen_crc32table97hostprogs-y := gen_crc32table
96clean-files := crc32table.h98clean-files := crc32table.h
97 99
lib/checksum.c+193−0
@@ -0,0 +1,193 @@
1/*
2 *
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
6 *
7 * IP/TCP/UDP checksumming routines
8 *
9 * Authors: Jorge Cwik, <jorge@laser.satlink.net>
10 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
11 * Tom May, <ftom@netcom.com>
12 * Andreas Schwab, <schwab@issan.informatik.uni-dortmund.de>
13 * Lots of code moved from tcp.c and ip.c; see those files
14 * for more names.
15 *
16 * 03/02/96 Jes Sorensen, Andreas Schwab, Roman Hodek:
17 * Fixed some nasty bugs, causing some horrible crashes.
18 * A: At some points, the sum (%0) was used as
19 * length-counter instead of the length counter
20 * (%1). Thanks to Roman Hodek for pointing this out.
21 * B: GCC seems to mess up if one uses too many
22 * data-registers to hold input values and one tries to
23 * specify d0 and d1 as scratch registers. Letting gcc
24 * choose these registers itself solves the problem.
25 *
26 * This program is free software; you can redistribute it and/or
27 * modify it under the terms of the GNU General Public License
28 * as published by the Free Software Foundation; either version
29 * 2 of the License, or (at your option) any later version.
30 */
31
32/* Revised by Kenneth Albanowski for m68knommu. Basic problem: unaligned access
33 kills, so most of the assembly has to go. */
34
35#include <linux/module.h>
36#include <net/checksum.h>
37
38#include <asm/byteorder.h>
39
40static inline unsigned short from32to16(unsigned long x)
41{
42 /* add up 16-bit and 16-bit for 16+c bit */
43 x = (x & 0xffff) + (x >> 16);
44 /* add up carry.. */
45 x = (x & 0xffff) + (x >> 16);
46 return x;
47}
48
49static unsigned int do_csum(const unsigned char *buff, int len)
50{
51 int odd, count;
52 unsigned long result = 0;
53
54 if (len <= 0)
55 goto out;
56 odd = 1 & (unsigned long) buff;
57 if (odd) {
58 result = *buff;
59 len--;
60 buff++;
61 }
62 count = len >> 1; /* nr of 16-bit words.. */
63 if (count) {
64 if (2 & (unsigned long) buff) {
65 result += *(unsigned short *) buff;
66 count--;
67 len -= 2;
68 buff += 2;
69 }
70 count >>= 1; /* nr of 32-bit words.. */
71 if (count) {
72 unsigned long carry = 0;
73 do {
74 unsigned long w = *(unsigned long *) buff;
75 count--;
76 buff += 4;
77 result += carry;
78 result += w;
79 carry = (w > result);
80 } while (count);
81 result += carry;
82 result = (result & 0xffff) + (result >> 16);
83 }
84 if (len & 2) {
85 result += *(unsigned short *) buff;
86 buff += 2;
87 }
88 }
89 if (len & 1)
90 result += (*buff << 8);
91 result = from32to16(result);
92 if (odd)
93 result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
94out:
95 return result;
96}
97
98/*
99 * This is a version of ip_compute_csum() optimized for IP headers,
100 * which always checksum on 4 octet boundaries.
101 */
102__sum16 ip_fast_csum(const void *iph, unsigned int ihl)
103{
104 return (__force __sum16)~do_csum(iph, ihl*4);
105}
106EXPORT_SYMBOL(ip_fast_csum);
107
108/*
109 * computes the checksum of a memory block at buff, length len,
110 * and adds in "sum" (32-bit)
111 *
112 * returns a 32-bit number suitable for feeding into itself
113 * or csum_tcpudp_magic
114 *
115 * this function must be called with even lengths, except
116 * for the last fragment, which may be odd
117 *
118 * it's best to have buff aligned on a 32-bit boundary
119 */
120__wsum csum_partial(const void *buff, int len, __wsum wsum)
121{
122 unsigned int sum = (__force unsigned int)wsum;
123 unsigned int result = do_csum(buff, len);
124
125 /* add in old sum, and carry.. */
126 result += sum;
127 if (sum > result)
128 result += 1;
129 return (__force __wsum)result;
130}
131EXPORT_SYMBOL(csum_partial);
132
133/*
134 * this routine is used for miscellaneous IP-like checksums, mainly
135 * in icmp.c
136 */
137__sum16 ip_compute_csum(const void *buff, int len)
138{
139 return (__force __sum16)~do_csum(buff, len);
140}
141EXPORT_SYMBOL(ip_compute_csum);
142
143/*
144 * copy from fs while checksumming, otherwise like csum_partial
145 */
146__wsum
147csum_partial_copy_from_user(const void __user *src, void *dst, int len,
148 __wsum sum, int *csum_err)
149{
150 int missing;
151
152 missing = __copy_from_user(dst, src, len);
153 if (missing) {
154 memset(dst + len - missing, 0, missing);
155 *csum_err = -EFAULT;
156 } else
157 *csum_err = 0;
158
159 return csum_partial(dst, len, sum);
160}
161EXPORT_SYMBOL(csum_partial_copy_from_user);
162
163/*
164 * copy from ds while checksumming, otherwise like csum_partial
165 */
166__wsum
167csum_partial_copy(const void *src, void *dst, int len, __wsum sum)
168{
169 memcpy(dst, src, len);
170 return csum_partial(dst, len, sum);
171}
172EXPORT_SYMBOL(csum_partial_copy);
173
174#ifndef csum_tcpudp_nofold
175__wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
176 unsigned short len,
177 unsigned short proto,
178 __wsum sum)
179{
180 unsigned long long s = (__force u32)sum;
181
182 s += (__force u32)saddr;
183 s += (__force u32)daddr;
184#ifdef __BIG_ENDIAN
185 s += proto + len;
186#else
187 s += (proto + len) << 8;
188#endif
189 s += (s >> 32);
190 return (__force __wsum)s;
191}
192EXPORT_SYMBOL(csum_tcpudp_nofold);
193#endif