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authorArnd Bergmann <arnd@arndb.de>2009-05-13 22:56:38 +0000
committerArnd Bergmann <arnd@klappe2.(none)>2009-06-11 21:02:51 +0200
commit26a28fa4fea5b8c65713aa50c124f76a88c7924d (patch)
tree95d5989e0cdcb4f565d7546b4c0fd76e30cfd249 /lib/checksum.c
parenteed417ddd52146f446595b5a7d8f21b1814b95b7 (diff)
downloadlinux-26a28fa4fea5b8c65713aa50c124f76a88c7924d.tar.gz
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> Cc: Michal Simek <monstr@monstr.eu> Signed-off-by: Remis Lima Baima <remis.developer@googlemail.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'lib/checksum.c')
-rw-r--r--lib/checksum.c193
1 files changed, 193 insertions, 0 deletions
diff --git a/lib/checksum.c b/lib/checksum.c
new file mode 100644
index 000000000000..12e5a1c91cda
--- /dev/null
+++ b/lib/checksum.c
@@ -0,0 +1,193 @@
+/*
+ *
+ * INET An implementation of the TCP/IP protocol suite for the LINUX
+ * operating system. INET is implemented using the BSD Socket
+ * interface as the means of communication with the user level.
+ *
+ * IP/TCP/UDP checksumming routines
+ *
+ * Authors: Jorge Cwik, <jorge@laser.satlink.net>
+ * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
+ * Tom May, <ftom@netcom.com>
+ * Andreas Schwab, <schwab@issan.informatik.uni-dortmund.de>
+ * Lots of code moved from tcp.c and ip.c; see those files
+ * for more names.
+ *
+ * 03/02/96 Jes Sorensen, Andreas Schwab, Roman Hodek:
+ * Fixed some nasty bugs, causing some horrible crashes.
+ * A: At some points, the sum (%0) was used as
+ * length-counter instead of the length counter
+ * (%1). Thanks to Roman Hodek for pointing this out.
+ * B: GCC seems to mess up if one uses too many
+ * data-registers to hold input values and one tries to
+ * specify d0 and d1 as scratch registers. Letting gcc
+ * choose these registers itself solves the problem.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+/* Revised by Kenneth Albanowski for m68knommu. Basic problem: unaligned access
+ kills, so most of the assembly has to go. */
+
+#include <linux/module.h>
+#include <net/checksum.h>
+
+#include <asm/byteorder.h>
+
+static inline unsigned short from32to16(unsigned long x)
+{
+ /* add up 16-bit and 16-bit for 16+c bit */
+ x = (x & 0xffff) + (x >> 16);
+ /* add up carry.. */
+ x = (x & 0xffff) + (x >> 16);
+ return x;
+}
+
+static unsigned int do_csum(const unsigned char *buff, int len)
+{
+ int odd, count;
+ unsigned long result = 0;
+
+ if (len <= 0)
+ goto out;
+ odd = 1 & (unsigned long) buff;
+ if (odd) {
+ result = *buff;
+ len--;
+ buff++;
+ }
+ count = len >> 1; /* nr of 16-bit words.. */
+ if (count) {
+ if (2 & (unsigned long) buff) {
+ result += *(unsigned short *) buff;
+ count--;
+ len -= 2;
+ buff += 2;
+ }
+ count >>= 1; /* nr of 32-bit words.. */
+ if (count) {
+ unsigned long carry = 0;
+ do {
+ unsigned long w = *(unsigned long *) buff;
+ count--;
+ buff += 4;
+ result += carry;
+ result += w;
+ carry = (w > result);
+ } while (count);
+ result += carry;
+ result = (result & 0xffff) + (result >> 16);
+ }
+ if (len & 2) {
+ result += *(unsigned short *) buff;
+ buff += 2;
+ }
+ }
+ if (len & 1)
+ result += (*buff << 8);
+ result = from32to16(result);
+ if (odd)
+ result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
+out:
+ return result;
+}
+
+/*
+ * This is a version of ip_compute_csum() optimized for IP headers,
+ * which always checksum on 4 octet boundaries.
+ */
+__sum16 ip_fast_csum(const void *iph, unsigned int ihl)
+{
+ return (__force __sum16)~do_csum(iph, ihl*4);
+}
+EXPORT_SYMBOL(ip_fast_csum);
+
+/*
+ * computes the checksum of a memory block at buff, length len,
+ * and adds in "sum" (32-bit)
+ *
+ * returns a 32-bit number suitable for feeding into itself
+ * or csum_tcpudp_magic
+ *
+ * this function must be called with even lengths, except
+ * for the last fragment, which may be odd
+ *
+ * it's best to have buff aligned on a 32-bit boundary
+ */
+__wsum csum_partial(const void *buff, int len, __wsum wsum)
+{
+ unsigned int sum = (__force unsigned int)wsum;
+ unsigned int result = do_csum(buff, len);
+
+ /* add in old sum, and carry.. */
+ result += sum;
+ if (sum > result)
+ result += 1;
+ return (__force __wsum)result;
+}
+EXPORT_SYMBOL(csum_partial);
+
+/*
+ * this routine is used for miscellaneous IP-like checksums, mainly
+ * in icmp.c
+ */
+__sum16 ip_compute_csum(const void *buff, int len)
+{
+ return (__force __sum16)~do_csum(buff, len);
+}
+EXPORT_SYMBOL(ip_compute_csum);
+
+/*
+ * copy from fs while checksumming, otherwise like csum_partial
+ */
+__wsum
+csum_partial_copy_from_user(const void __user *src, void *dst, int len,
+ __wsum sum, int *csum_err)
+{
+ int missing;
+
+ missing = __copy_from_user(dst, src, len);
+ if (missing) {
+ memset(dst + len - missing, 0, missing);
+ *csum_err = -EFAULT;
+ } else
+ *csum_err = 0;
+
+ return csum_partial(dst, len, sum);
+}
+EXPORT_SYMBOL(csum_partial_copy_from_user);
+
+/*
+ * copy from ds while checksumming, otherwise like csum_partial
+ */
+__wsum
+csum_partial_copy(const void *src, void *dst, int len, __wsum sum)
+{
+ memcpy(dst, src, len);
+ return csum_partial(dst, len, sum);
+}
+EXPORT_SYMBOL(csum_partial_copy);
+
+#ifndef csum_tcpudp_nofold
+__wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
+ unsigned short len,
+ unsigned short proto,
+ __wsum sum)
+{
+ unsigned long long s = (__force u32)sum;
+
+ s += (__force u32)saddr;
+ s += (__force u32)daddr;
+#ifdef __BIG_ENDIAN
+ s += proto + len;
+#else
+ s += (proto + len) << 8;
+#endif
+ s += (s >> 32);
+ return (__force __wsum)s;
+}
+EXPORT_SYMBOL(csum_tcpudp_nofold);
+#endif