2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
6 * Copyright (C) 1995, 96, 97, 98, 99, 2001 by Ralf Baechle
7 * Copyright (C) 1999 Silicon Graphics, Inc.
8 * Copyright (C) 2001 Thiemo Seufer.
9 * Copyright (C) 2002 Maciej W. Rozycki
11 #ifndef _ASM_CHECKSUM_H
12 #define _ASM_CHECKSUM_H
14 #include <linux/config.h>
15 #include <linux/in6.h>
17 #include <asm/uaccess.h>
20 * computes the checksum of a memory block at buff, length len,
21 * and adds in "sum" (32-bit)
23 * returns a 32-bit number suitable for feeding into itself
24 * or csum_tcpudp_magic
26 * this function must be called with even lengths, except
27 * for the last fragment, which may be odd
29 * it's best to have buff aligned on a 32-bit boundary
31 unsigned int csum_partial(const unsigned char *buff, int len, unsigned int sum);
34 * this is a new version of the above that records errors it finds in *errp,
35 * but continues and zeros the rest of the buffer.
37 unsigned int csum_partial_copy_from_user(const char *src, char *dst, int len,
38 unsigned int sum, int *errp);
41 * Copy and checksum to user
43 #define HAVE_CSUM_COPY_USER
44 static inline unsigned int csum_and_copy_to_user (const char *src,
49 sum = csum_partial(src, len, sum);
51 if (copy_to_user(dst, src, len)) {
60 * the same as csum_partial, but copies from user space (but on MIPS
61 * we have just one address space, so this is identical to the above)
63 unsigned int csum_partial_copy_nocheck(const char *src, char *dst, int len,
67 * Fold a partial checksum without adding pseudo headers
69 static inline unsigned short int csum_fold(unsigned int sum)
72 ".set\tnoat\t\t\t# csum_fold\n\t"
87 * This is a version of ip_compute_csum() optimized for IP headers,
88 * which always checksum on 4 octet boundaries.
90 * By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
93 static inline unsigned short ip_fast_csum(unsigned char *iph, unsigned int ihl)
95 unsigned int *word = (unsigned int *) iph;
96 unsigned int *stop = word + ihl;
102 carry = (csum < word[1]);
106 carry = (csum < word[2]);
110 carry = (csum < word[3]);
116 carry = (csum < *word);
119 } while (word != stop);
121 return csum_fold(csum);
124 static inline unsigned int csum_tcpudp_nofold(unsigned long saddr,
125 unsigned long daddr, unsigned short len, unsigned short proto,
129 ".set\tnoat\t\t\t# csum_tcpudp_nofold\n\t"
132 "sltu\t$1, %0, %2\n\t"
136 "sltu\t$1, %0, %3\n\t"
140 "sltu\t$1, %0, %4\n\t"
147 "dsll32\t$1, %0, 0\n\t"
149 "dsrl32\t%0, %0, 0\n\t"
153 : "0" (daddr), "r"(saddr),
155 "r" (((unsigned long)htons(len)<<16) + proto*256),
157 "r" (((unsigned long)(proto)<<16) + len),
165 * computes the checksum of the TCP/UDP pseudo-header
166 * returns a 16-bit checksum, already complemented
168 static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
171 unsigned short proto,
174 return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
178 * this routine is used for miscellaneous IP-like checksums, mainly
181 static inline unsigned short ip_compute_csum(unsigned char * buff, int len)
183 return csum_fold(csum_partial(buff, len, 0));
186 #define _HAVE_ARCH_IPV6_CSUM
187 static __inline__ unsigned short int csum_ipv6_magic(struct in6_addr *saddr,
188 struct in6_addr *daddr,
190 unsigned short proto,
194 ".set\tpush\t\t\t# csum_ipv6_magic\n\t"
195 ".set\tnoreorder\n\t"
197 "addu\t%0, %5\t\t\t# proto (long in network byte order)\n\t"
198 "sltu\t$1, %0, %5\n\t"
201 "addu\t%0, %6\t\t\t# csum\n\t"
202 "sltu\t$1, %0, %6\n\t"
203 "lw\t%1, 0(%2)\t\t\t# four words source address\n\t"
206 "sltu\t$1, %0, %1\n\t"
211 "sltu\t$1, %0, %1\n\t"
216 "sltu\t$1, %0, %1\n\t"
221 "sltu\t$1, %0, %1\n\t"
226 "sltu\t$1, %0, %1\n\t"
231 "sltu\t$1, %0, %1\n\t"
236 "sltu\t$1, %0, %1\n\t"
241 "sltu\t$1, %0, %1\n\t"
243 "addu\t%0, $1\t\t\t# Add final carry\n\t"
245 : "=r" (sum), "=r" (proto)
246 : "r" (saddr), "r" (daddr),
247 "0" (htonl(len)), "1" (htonl(proto)), "r" (sum));
249 return csum_fold(sum);
252 #endif /* _ASM_CHECKSUM_H */