ia64/linux-2.6.18-xen.hg

view arch/m68knommu/lib/checksum.c @ 854:950b9eb27661

usbback: fix urb interval value for interrupt urbs.

Signed-off-by: Noboru Iwamatsu <n_iwamatsu@jp.fujitsu.com>
author Keir Fraser <keir.fraser@citrix.com>
date Mon Apr 06 13:51:20 2009 +0100 (2009-04-06)
parents 831230e53067
children
line source
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 * IP/TCP/UDP checksumming routines
7 *
8 * Authors: Jorge Cwik, <jorge@laser.satlink.net>
9 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
10 * Tom May, <ftom@netcom.com>
11 * Andreas Schwab, <schwab@issan.informatik.uni-dortmund.de>
12 * Lots of code moved from tcp.c and ip.c; see those files
13 * for more names.
14 *
15 * 03/02/96 Jes Sorensen, Andreas Schwab, Roman Hodek:
16 * Fixed some nasty bugs, causing some horrible crashes.
17 * A: At some points, the sum (%0) was used as
18 * length-counter instead of the length counter
19 * (%1). Thanks to Roman Hodek for pointing this out.
20 * B: GCC seems to mess up if one uses too many
21 * data-registers to hold input values and one tries to
22 * specify d0 and d1 as scratch registers. Letting gcc choose these
23 * registers itself solves the problem.
24 *
25 * This program is free software; you can redistribute it and/or
26 * modify it under the terms of the GNU General Public License
27 * as published by the Free Software Foundation; either version
28 * 2 of the License, or (at your option) any later version.
29 */
31 /* Revised by Kenneth Albanowski for m68knommu. Basic problem: unaligned access kills, so most
32 of the assembly has to go. */
34 #include <linux/module.h>
35 #include <net/checksum.h>
37 static inline unsigned short from32to16(unsigned long x)
38 {
39 /* add up 16-bit and 16-bit for 16+c bit */
40 x = (x & 0xffff) + (x >> 16);
41 /* add up carry.. */
42 x = (x & 0xffff) + (x >> 16);
43 return x;
44 }
46 static unsigned long do_csum(const unsigned char * buff, int len)
47 {
48 int odd, count;
49 unsigned long result = 0;
51 if (len <= 0)
52 goto out;
53 odd = 1 & (unsigned long) buff;
54 if (odd) {
55 result = *buff;
56 len--;
57 buff++;
58 }
59 count = len >> 1; /* nr of 16-bit words.. */
60 if (count) {
61 if (2 & (unsigned long) buff) {
62 result += *(unsigned short *) buff;
63 count--;
64 len -= 2;
65 buff += 2;
66 }
67 count >>= 1; /* nr of 32-bit words.. */
68 if (count) {
69 unsigned long carry = 0;
70 do {
71 unsigned long w = *(unsigned long *) buff;
72 count--;
73 buff += 4;
74 result += carry;
75 result += w;
76 carry = (w > result);
77 } while (count);
78 result += carry;
79 result = (result & 0xffff) + (result >> 16);
80 }
81 if (len & 2) {
82 result += *(unsigned short *) buff;
83 buff += 2;
84 }
85 }
86 if (len & 1)
87 result += (*buff << 8);
88 result = from32to16(result);
89 if (odd)
90 result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
91 out:
92 return result;
93 }
95 /*
96 * This is a version of ip_compute_csum() optimized for IP headers,
97 * which always checksum on 4 octet boundaries.
98 */
99 unsigned short ip_fast_csum(unsigned char * iph, unsigned int ihl)
100 {
101 return ~do_csum(iph,ihl*4);
102 }
104 /*
105 * computes the checksum of a memory block at buff, length len,
106 * and adds in "sum" (32-bit)
107 *
108 * returns a 32-bit number suitable for feeding into itself
109 * or csum_tcpudp_magic
110 *
111 * this function must be called with even lengths, except
112 * for the last fragment, which may be odd
113 *
114 * it's best to have buff aligned on a 32-bit boundary
115 */
116 unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum)
117 {
118 unsigned int result = do_csum(buff, len);
120 /* add in old sum, and carry.. */
121 result += sum;
122 if (sum > result)
123 result += 1;
124 return result;
125 }
127 EXPORT_SYMBOL(csum_partial);
129 /*
130 * this routine is used for miscellaneous IP-like checksums, mainly
131 * in icmp.c
132 */
133 unsigned short ip_compute_csum(const unsigned char * buff, int len)
134 {
135 return ~do_csum(buff,len);
136 }
138 /*
139 * copy from fs while checksumming, otherwise like csum_partial
140 */
142 unsigned int
143 csum_partial_copy_from_user(const unsigned char *src, unsigned char *dst,
144 int len, int sum, int *csum_err)
145 {
146 if (csum_err) *csum_err = 0;
147 memcpy(dst, src, len);
148 return csum_partial(dst, len, sum);
149 }
151 /*
152 * copy from ds while checksumming, otherwise like csum_partial
153 */
155 unsigned int
156 csum_partial_copy(const unsigned char *src, unsigned char *dst, int len, int sum)
157 {
158 memcpy(dst, src, len);
159 return csum_partial(dst, len, sum);
160 }