~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/arch/frv/lib/checksum.c

Version: ~ [ linux-5.11-rc3 ] ~ [ linux-5.10.7 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.89 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.167 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.215 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.251 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.251 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.85 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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  */
 30 
 31 /* Revised by Kenneth Albanowski for m68knommu. Basic problem: unaligned access kills, so most
 32    of the assembly has to go. */
 33 
 34 #include <net/checksum.h>
 35 #include <linux/module.h>
 36 
 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 }
 45 
 46 static unsigned long do_csum(const unsigned char * buff, int len)
 47 {
 48         int odd, count;
 49         unsigned long result = 0;
 50 
 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 }
 94 
 95 /*
 96  * computes the checksum of a memory block at buff, length len,
 97  * and adds in "sum" (32-bit)
 98  *
 99  * returns a 32-bit number suitable for feeding into itself
100  * or csum_tcpudp_magic
101  *
102  * this function must be called with even lengths, except
103  * for the last fragment, which may be odd
104  *
105  * it's best to have buff aligned on a 32-bit boundary
106  */
107 __wsum csum_partial(const void *buff, int len, __wsum sum)
108 {
109         unsigned int result = do_csum(buff, len);
110 
111         /* add in old sum, and carry.. */
112         result += (__force u32)sum;
113         if ((__force u32)sum > result)
114                 result += 1;
115         return (__force __wsum)result;
116 }
117 
118 EXPORT_SYMBOL(csum_partial);
119 
120 /*
121  * this routine is used for miscellaneous IP-like checksums, mainly
122  * in icmp.c
123  */
124 __sum16 ip_compute_csum(const void *buff, int len)
125 {
126         return (__force __sum16)~do_csum(buff, len);
127 }
128 
129 EXPORT_SYMBOL(ip_compute_csum);
130 
131 /*
132  * copy from fs while checksumming, otherwise like csum_partial
133  */
134 __wsum
135 csum_partial_copy_from_user(const void __user *src, void *dst,
136                             int len, __wsum sum, int *csum_err)
137 {
138         int rem;
139 
140         if (csum_err)
141                 *csum_err = 0;
142 
143         rem = copy_from_user(dst, src, len);
144         if (rem != 0) {
145                 if (csum_err)
146                         *csum_err = -EFAULT;
147                 memset(dst + len - rem, 0, rem);
148                 len = rem;
149         }
150 
151         return csum_partial(dst, len, sum);
152 }
153 
154 EXPORT_SYMBOL(csum_partial_copy_from_user);
155 
156 /*
157  * copy from ds while checksumming, otherwise like csum_partial
158  */
159 __wsum
160 csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
161 {
162         memcpy(dst, src, len);
163         return csum_partial(dst, len, sum);
164 }
165 
166 EXPORT_SYMBOL(csum_partial_copy_nocheck);
167 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp