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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+ */
16+extern __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+ */
25+extern __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+ */
33+extern __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+ */
43+extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
44+
45+/*
46+ * Fold a partial checksum
47+ */
48+static 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+ */
61+extern __wsum
62+csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
63+ unsigned short proto, __wsum sum);
64+#endif
65+
66+static inline __sum16
67+csum_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+ */
77+extern __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-$(CONFIG_NLATTR) += nlattr.o · 91 unmodified lines
9292
9393 obj-$(CONFIG_DMA_API_DEBUG) += dma-debug.o
9494
95+obj-$(CONFIG_GENERIC_CSUM) += checksum.o
96+
9597 hostprogs-y := gen_crc32table
9698 clean-files := crc32table.h
9799
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+
40+static 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+
49+static 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);
94+out:
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+}
106+EXPORT_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+}
131+EXPORT_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+}
141+EXPORT_SYMBOL(ip_compute_csum);
142+
143+/*
144+ * copy from fs while checksumming, otherwise like csum_partial
145+ */
146+__wsum
147+csum_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+}
161+EXPORT_SYMBOL(csum_partial_copy_from_user);
162+
163+/*
164+ * copy from ds while checksumming, otherwise like csum_partial
165+ */
166+__wsum
167+csum_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+}
172+EXPORT_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+}
192+EXPORT_SYMBOL(csum_tcpudp_nofold);
193+#endif