/* * File: arch/blackfin/lib/checksum.c * Based on: none - original work * Author: * * Created: * Description: An implementation of the TCP/IP protocol suite for the LINUX * operating system. INET is implemented using the BSD Socket * interface as the means of communication with the user level. * * Modified: * Copyright 2004-2006 Analog Devices Inc. * * Bugs: Enter bugs at http://blackfin.uclinux.org/ * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see the file COPYING, or write * to the Free Software Foundation, Inc., * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ #include <net/checksum.h> #include <asm/checksum.h> #ifdef CONFIG_IP_CHECKSUM_L1 static unsigned short do_csum(const unsigned char *buff, int len)__attribute__((l1_text)); #endif static unsigned short do_csum(const unsigned char *buff, int len) { register unsigned long sum = 0; int swappem = 0; if (1 & (unsigned long)buff) { sum = *buff << 8; buff++; len--; ++swappem; } while (len > 1) { sum += *(unsigned short *)buff; buff += 2; len -= 2; } if (len > 0) sum += *buff; /* Fold 32-bit sum to 16 bits */ while (sum >> 16) sum = (sum & 0xffff) + (sum >> 16); if (swappem) sum = ((sum & 0xff00) >> 8) + ((sum & 0x00ff) << 8); return sum; } /* * This is a version of ip_compute_csum() optimized for IP headers, * which always checksum on 4 octet boundaries. */ unsigned short ip_fast_csum(unsigned char *iph, unsigned int ihl) { return ~do_csum(iph, ihl * 4); } /* * computes the checksum of a memory block at buff, length len, * and adds in "sum" (32-bit) * * returns a 32-bit number suitable for feeding into itself * or csum_tcpudp_magic * * this function must be called with even lengths, except * for the last fragment, which may be odd * * it's best to have buff aligned on a 32-bit boundary */ unsigned int csum_partial(const unsigned char *buff, int len, unsigned int sum) { /* * Just in case we get nasty checksum data... * Like 0xffff6ec3 in the case of our IPv6 multicast header. * We fold to begin with, as well as at the end. */ sum = (sum & 0xffff) + (sum >> 16); sum += do_csum(buff, len); sum = (sum & 0xffff) + (sum >> 16); return sum; } /* * this routine is used for miscellaneous IP-like checksums, mainly * in icmp.c */ unsigned short ip_compute_csum(const unsigned char *buff, int len) { return ~do_csum(buff, len); } /* * copy from fs while checksumming, otherwise like csum_partial */ unsigned int csum_partial_copy_from_user(const unsigned char *src, unsigned char *dst, int len, int sum, int *csum_err) { if (csum_err) *csum_err = 0; memcpy(dst, src, len); return csum_partial(dst, len, sum); } /* * copy from ds while checksumming, otherwise like csum_partial */ unsigned int csum_partial_copy(const unsigned char *src, unsigned char *dst, int len, int sum) { memcpy(dst, src, len); return csum_partial(dst, len, sum); }

Generated by Doxygen 1.6.0 Back to index