2005-04-16 16:20:36 -06:00
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/*
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* arch/alpha/lib/checksum.c
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*
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* This file contains network checksum routines that are better done
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* in an architecture-specific manner due to speed..
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* Comments in other versions indicate that the algorithms are from RFC1071
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*
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* accellerated versions (and 21264 assembly versions ) contributed by
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* Rick Gorton <rick.gorton@alpha-processor.com>
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*/
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#include <linux/module.h>
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#include <linux/string.h>
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#include <asm/byteorder.h>
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static inline unsigned short from64to16(unsigned long x)
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{
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/* Using extract instructions is a bit more efficient
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than the original shift/bitmask version. */
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union {
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unsigned long ul;
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unsigned int ui[2];
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unsigned short us[4];
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} in_v, tmp_v, out_v;
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in_v.ul = x;
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tmp_v.ul = (unsigned long) in_v.ui[0] + (unsigned long) in_v.ui[1];
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/* Since the bits of tmp_v.sh[3] are going to always be zero,
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we don't have to bother to add that in. */
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out_v.ul = (unsigned long) tmp_v.us[0] + (unsigned long) tmp_v.us[1]
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+ (unsigned long) tmp_v.us[2];
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/* Similarly, out_v.us[2] is always zero for the final add. */
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return out_v.us[0] + out_v.us[1];
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}
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/*
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* computes the checksum of the TCP/UDP pseudo-header
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* returns a 16-bit checksum, already complemented.
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*/
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2006-11-14 22:14:53 -07:00
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__sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
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unsigned short len,
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unsigned short proto,
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2006-11-14 22:14:53 -07:00
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__wsum sum)
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2005-04-16 16:20:36 -06:00
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{
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2006-11-14 22:14:53 -07:00
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return (__force __sum16)~from64to16(
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(__force u64)saddr + (__force u64)daddr +
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(__force u64)sum + ((len + proto) << 8));
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2005-04-16 16:20:36 -06:00
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}
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2006-11-14 22:14:53 -07:00
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__wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
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2005-04-16 16:20:36 -06:00
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unsigned short len,
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unsigned short proto,
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2006-11-14 22:14:53 -07:00
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__wsum sum)
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2005-04-16 16:20:36 -06:00
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{
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unsigned long result;
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2006-11-14 22:14:53 -07:00
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result = (__force u64)saddr + (__force u64)daddr +
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(__force u64)sum + ((len + proto) << 8);
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2005-04-16 16:20:36 -06:00
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/* Fold down to 32-bits so we don't lose in the typedef-less
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network stack. */
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/* 64 to 33 */
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result = (result & 0xffffffff) + (result >> 32);
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/* 33 to 32 */
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result = (result & 0xffffffff) + (result >> 32);
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2006-11-14 22:14:53 -07:00
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return (__force __wsum)result;
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2005-04-16 16:20:36 -06:00
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}
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/*
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* Do a 64-bit checksum on an arbitrary memory area..
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*
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* This isn't a great routine, but it's not _horrible_ either. The
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* inner loop could be unrolled a bit further, and there are better
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* ways to do the carry, but this is reasonable.
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*/
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static inline unsigned long do_csum(const unsigned char * buff, int len)
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{
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int odd, count;
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unsigned long result = 0;
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if (len <= 0)
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goto out;
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odd = 1 & (unsigned long) buff;
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if (odd) {
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result = *buff << 8;
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len--;
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buff++;
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}
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count = len >> 1; /* nr of 16-bit words.. */
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if (count) {
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if (2 & (unsigned long) buff) {
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result += *(unsigned short *) buff;
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count--;
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len -= 2;
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buff += 2;
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}
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count >>= 1; /* nr of 32-bit words.. */
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if (count) {
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if (4 & (unsigned long) buff) {
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result += *(unsigned int *) buff;
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count--;
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len -= 4;
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buff += 4;
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}
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count >>= 1; /* nr of 64-bit words.. */
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if (count) {
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unsigned long carry = 0;
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do {
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unsigned long w = *(unsigned long *) buff;
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count--;
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buff += 8;
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result += carry;
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result += w;
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carry = (w > result);
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} while (count);
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result += carry;
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result = (result & 0xffffffff) + (result >> 32);
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}
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if (len & 4) {
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result += *(unsigned int *) buff;
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buff += 4;
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}
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}
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if (len & 2) {
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result += *(unsigned short *) buff;
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buff += 2;
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}
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}
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if (len & 1)
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result += *buff;
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result = from64to16(result);
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if (odd)
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result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
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out:
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return result;
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}
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/*
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* This is a version of ip_compute_csum() optimized for IP headers,
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* which always checksum on 4 octet boundaries.
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*/
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__sum16 ip_fast_csum(const void *iph, unsigned int ihl)
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{
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return (__force __sum16)~do_csum(iph,ihl*4);
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2005-04-16 16:20:36 -06:00
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}
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/*
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* computes the checksum of a memory block at buff, length len,
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* and adds in "sum" (32-bit)
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*
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* returns a 32-bit number suitable for feeding into itself
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* or csum_tcpudp_magic
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*
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* this function must be called with even lengths, except
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* for the last fragment, which may be odd
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*
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* it's best to have buff aligned on a 32-bit boundary
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*/
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2006-11-14 22:14:53 -07:00
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__wsum csum_partial(const void *buff, int len, __wsum sum)
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{
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unsigned long result = do_csum(buff, len);
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/* add in old sum, and carry.. */
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result += (__force u32)sum;
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2005-04-16 16:20:36 -06:00
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/* 32+c bits -> 32 bits */
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result = (result & 0xffffffff) + (result >> 32);
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2006-11-14 22:14:53 -07:00
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return (__force __wsum)result;
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2005-04-16 16:20:36 -06:00
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}
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EXPORT_SYMBOL(csum_partial);
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/*
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* this routine is used for miscellaneous IP-like checksums, mainly
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* in icmp.c
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*/
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2006-11-14 22:14:53 -07:00
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__sum16 ip_compute_csum(const void *buff, int len)
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{
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2006-11-14 22:14:53 -07:00
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return (__force __sum16)~from64to16(do_csum(buff,len));
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2005-04-16 16:20:36 -06:00
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}
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