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, char *dst,
48 sum = csum_partial(src, len, sum);
50 if (copy_to_user(dst, src, len)) {
59 * the same as csum_partial, but copies from user space (but on MIPS
60 * we have just one address space, so this is identical to the above)
62 unsigned int csum_partial_copy_nocheck(const char *src, char *dst, int len,
66 * Fold a partial checksum without adding pseudo headers
68 static inline unsigned short int csum_fold(unsigned int sum)
71 ".set\tnoat\t\t\t# csum_fold\n\t"
86 * This is a version of ip_compute_csum() optimized for IP headers,
87 * which always checksum on 4 octet boundaries.
89 * By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
92 static inline unsigned short ip_fast_csum(unsigned char *iph, unsigned int ihl)
94 unsigned int *word = (unsigned int *) iph;
95 unsigned int *stop = word + ihl;
101 carry = (csum < word[1]);
105 carry = (csum < word[2]);
109 carry = (csum < word[3]);
115 carry = (csum < *word);
118 } while (word != stop);
120 return csum_fold(csum);
124 * computes the checksum of the TCP/UDP pseudo-header
125 * returns a 16-bit checksum, already complemented
127 static inline unsigned int csum_tcpudp_nofold(unsigned long saddr,
128 unsigned long daddr, unsigned short len, unsigned short proto,
132 ".set\tnoat\t\t\t# csum_tcpudp_nofold\n\t"
135 "sltu\t$1, %0, %2\n\t"
139 "sltu\t$1, %0, %3\n\t"
143 "sltu\t$1, %0, %4\n\t"
150 "dsll32\t$1, %0, 0\n\t"
152 "dsrl32\t%0, %0, 0\n\t"
156 : "0" (daddr), "r"(saddr),
158 "r" (((unsigned long)htons(len)<<16) + proto*256),
160 "r" (((unsigned long)(proto)<<16) + len),
168 * computes the checksum of the TCP/UDP pseudo-header
169 * returns a 16-bit checksum, already complemented
171 static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
174 unsigned short proto,
177 return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
181 * this routine is used for miscellaneous IP-like checksums, mainly
184 static inline unsigned short ip_compute_csum(unsigned char * buff, int len)
186 return csum_fold(csum_partial(buff, len, 0));
189 #define _HAVE_ARCH_IPV6_CSUM
190 static __inline__ unsigned short int csum_ipv6_magic(struct in6_addr *saddr,
191 struct in6_addr *daddr,
193 unsigned short proto,
197 ".set\tpush\t\t\t# csum_ipv6_magic\n\t"
198 ".set\tnoreorder\n\t"
200 "addu\t%0, %5\t\t\t# proto (long in network byte order)\n\t"
201 "sltu\t$1, %0, %5\n\t"
204 "addu\t%0, %6\t\t\t# csum\n\t"
205 "sltu\t$1, %0, %6\n\t"
206 "lw\t%1, 0(%2)\t\t\t# four words source address\n\t"
209 "sltu\t$1, %0, %1\n\t"
214 "sltu\t$1, %0, %1\n\t"
219 "sltu\t$1, %0, %1\n\t"
224 "sltu\t$1, %0, %1\n\t"
229 "sltu\t$1, %0, %1\n\t"
234 "sltu\t$1, %0, %1\n\t"
239 "sltu\t$1, %0, %1\n\t"
244 "sltu\t$1, %0, %1\n\t"
246 "addu\t%0, $1\t\t\t# Add final carry\n\t"
248 : "=r" (sum), "=r" (proto)
249 : "r" (saddr), "r" (daddr),
250 "0" (htonl(len)), "1" (htonl(proto)), "r" (sum));
252 return csum_fold(sum);
255 #endif /* _ASM_CHECKSUM_H */