1/* 2 * File: arch/blackfin/lib/checksum.c 3 * Based on: none - original work 4 * Author: 5 * 6 * Created: 7 * Description: An implementation of the TCP/IP protocol suite for the LINUX 8 * operating system. INET is implemented using the BSD Socket 9 * interface as the means of communication with the user level. 10 * 11 * Modified: 12 * Copyright 2004-2006 Analog Devices Inc. 13 * 14 * Bugs: Enter bugs at http://blackfin.uclinux.org/ 15 * 16 * This program is free software; you can redistribute it and/or modify 17 * it under the terms of the GNU General Public License as published by 18 * the Free Software Foundation; either version 2 of the License, or 19 * (at your option) any later version. 20 * 21 * This program is distributed in the hope that it will be useful, 22 * but WITHOUT ANY WARRANTY; without even the implied warranty of 23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 24 * GNU General Public License for more details. 25 * 26 * You should have received a copy of the GNU General Public License 27 * along with this program; if not, see the file COPYING, or write 28 * to the Free Software Foundation, Inc., 29 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 30 */ 31 32#include <net/checksum.h> 33#include <asm/checksum.h> 34 35#ifdef CONFIG_IP_CHECKSUM_L1 36static unsigned short do_csum(const unsigned char *buff, int len)__attribute__((l1_text)); 37#endif 38 39static unsigned short do_csum(const unsigned char *buff, int len) 40{ 41 register unsigned long sum = 0; 42 int swappem = 0; 43 44 if (1 & (unsigned long)buff) { 45 sum = *buff << 8; 46 buff++; 47 len--; 48 ++swappem; 49 } 50 51 while (len > 1) { 52 sum += *(unsigned short *)buff; 53 buff += 2; 54 len -= 2; 55 } 56 57 if (len > 0) 58 sum += *buff; 59 60 /* Fold 32-bit sum to 16 bits */ 61 while (sum >> 16) 62 sum = (sum & 0xffff) + (sum >> 16); 63 64 if (swappem) 65 sum = ((sum & 0xff00) >> 8) + ((sum & 0x00ff) << 8); 66 67 return sum; 68 69} 70 71/* 72 * This is a version of ip_compute_csum() optimized for IP headers, 73 * which always checksum on 4 octet boundaries. 74 */ 75unsigned short ip_fast_csum(unsigned char *iph, unsigned int ihl) 76{ 77 return ~do_csum(iph, ihl * 4); 78} 79 80/* 81 * computes the checksum of a memory block at buff, length len, 82 * and adds in "sum" (32-bit) 83 * 84 * returns a 32-bit number suitable for feeding into itself 85 * or csum_tcpudp_magic 86 * 87 * this function must be called with even lengths, except 88 * for the last fragment, which may be odd 89 * 90 * it's best to have buff aligned on a 32-bit boundary 91 */ 92unsigned int csum_partial(const unsigned char *buff, int len, unsigned int sum) 93{ 94 /* 95 * Just in case we get nasty checksum data... 96 * Like 0xffff6ec3 in the case of our IPv6 multicast header. 97 * We fold to begin with, as well as at the end. 98 */ 99 sum = (sum & 0xffff) + (sum >> 16); 100 101 sum += do_csum(buff, len); 102 103 sum = (sum & 0xffff) + (sum >> 16); 104 105 return sum; 106} 107 108/* 109 * this routine is used for miscellaneous IP-like checksums, mainly 110 * in icmp.c 111 */ 112unsigned short ip_compute_csum(const unsigned char *buff, int len) 113{ 114 return ~do_csum(buff, len); 115} 116 117/* 118 * copy from fs while checksumming, otherwise like csum_partial 119 */ 120 121unsigned int 122csum_partial_copy_from_user(const unsigned char *src, unsigned char *dst, 123 int len, int sum, int *csum_err) 124{ 125 if (csum_err) 126 *csum_err = 0; 127 memcpy(dst, src, len); 128 return csum_partial(dst, len, sum); 129} 130 131/* 132 * copy from ds while checksumming, otherwise like csum_partial 133 */ 134 135unsigned int csum_partial_copy(const unsigned char *src, unsigned char *dst, 136 int len, int sum) 137{ 138 memcpy(dst, src, len); 139 return csum_partial(dst, len, sum); 140} 141