ia64/linux-2.6.18-xen.hg

view arch/v850/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 * 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>
26 static 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 }
38 static inline unsigned int do_csum(const unsigned char * buff, int len)
39 {
40 int odd, count;
41 unsigned int result = 0;
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);
83 out:
84 return result;
85 }
87 /*
88 * This is a version of ip_compute_csum() optimized for IP headers,
89 * which always checksum on 4 octet boundaries.
90 */
91 unsigned short ip_fast_csum(unsigned char * iph, unsigned int ihl)
92 {
93 return ~do_csum(iph,ihl*4);
94 }
96 /*
97 * this routine is used for miscellaneous IP-like checksums, mainly
98 * in icmp.c
99 */
100 unsigned short ip_compute_csum(const unsigned char * buff, int len)
101 {
102 return ~do_csum(buff,len);
103 }
105 /*
106 * computes a partial checksum, e.g. for TCP/UDP fragments
107 */
108 unsigned int csum_partial(const unsigned char *buff, int len, unsigned int sum)
109 {
110 unsigned int result = do_csum(buff, len);
112 /* add in old sum, and carry.. */
113 result += sum;
114 if(sum > result)
115 result += 1;
116 return result;
117 }
119 EXPORT_SYMBOL(csum_partial);
121 /*
122 * copy while checksumming, otherwise like csum_partial
123 */
124 unsigned 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);
134 return sum;
135 }
137 /*
138 * Copy from userspace and compute checksum. If we catch an exception
139 * then zero the rest of the buffer.
140 */
141 unsigned int csum_partial_copy_from_user (const unsigned char *src,
142 unsigned char *dst,
143 int len, unsigned int sum,
144 int *err_ptr)
145 {
146 int missing;
148 missing = copy_from_user(dst, src, len);
149 if (missing) {
150 memset(dst + len - missing, 0, missing);
151 *err_ptr = -EFAULT;
152 }
154 return csum_partial(dst, len, sum);
155 }