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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 | /* * INET 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. * * MIPS specific IP/TCP/UDP checksumming routines * * Authors: Ralf Baechle, <ralf@waldorf-gmbh.de> * Lots of code moved from tcp.c and ip.c; see those files * for more names. * * 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. * * $Id: checksum.c,v 1.1 2002/09/28 14:58:40 gerg Exp $ */ #include <net/checksum.h> #include <linux/module.h> #include <linux/types.h> #include <asm/byteorder.h> #include <asm/string.h> #include <asm/uaccess.h> static inline unsigned short from32to16 (unsigned long sum) { unsigned int result; /* %0 %1 hsw %1, %0 H L L H add %1, %0 H L H+L+C H+L */ asm ("hsw %1, %0; add %1, %0" : "=&r" (result) : "r" (sum)); return result >> 16; } static inline unsigned int do_csum(const unsigned char * buff, int len) { int odd, count; unsigned int result = 0; if (len <= 0) goto out; odd = 1 & (unsigned long) buff; if (odd) { result = be16_to_cpu(*buff); len--; buff++; } count = len >> 1; /* nr of 16-bit words.. */ if (count) { if (2 & (unsigned long) buff) { result += *(unsigned short *) buff; count--; len -= 2; buff += 2; } count >>= 1; /* nr of 32-bit words.. */ if (count) { unsigned int carry = 0; do { unsigned int w = *(unsigned int *) buff; count--; buff += 4; result += carry; result += w; carry = (w > result); } while (count); result += carry; result = (result & 0xffff) + (result >> 16); } if (len & 2) { result += *(unsigned short *) buff; buff += 2; } } if (len & 1) result += le16_to_cpu(*buff); result = from32to16(result); if (odd) result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); out: return result; } /* * 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); } /* * 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); } /* * computes a partial checksum, e.g. for TCP/UDP fragments */ unsigned int csum_partial(const unsigned char *buff, int len, unsigned int sum) { unsigned int result = do_csum(buff, len); /* add in old sum, and carry.. */ result += sum; if(sum > result) result += 1; return result; } EXPORT_SYMBOL(csum_partial); /* * copy while checksumming, otherwise like csum_partial */ unsigned int csum_partial_copy(const unsigned char *src, unsigned char *dst, int len, unsigned int sum) { /* * It's 2:30 am and I don't feel like doing it real ... * This is lots slower than the real thing (tm) */ sum = csum_partial(src, len, sum); memcpy(dst, src, len); return sum; } /* * Copy from userspace and compute checksum. If we catch an exception * then zero the rest of the buffer. */ unsigned int csum_partial_copy_from_user (const unsigned char *src, unsigned char *dst, int len, unsigned int sum, int *err_ptr) { int missing; missing = copy_from_user(dst, src, len); if (missing) { memset(dst + len - missing, 0, missing); *err_ptr = -EFAULT; } return csum_partial(dst, len, sum); } |