/* * 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. */ __sum16 ip_fast_csum(const void *iph, unsigned int ihl) { return (__force __sum16)~do_csum(iph,ihl*4); } /* * this routine is used for miscellaneous IP-like checksums, mainly * in icmp.c */ __sum16 ip_compute_csum(const void *buff, int len) { return (__force __sum16)~do_csum(buff,len); } /* * computes a partial checksum, e.g. for TCP/UDP fragments */ __wsum csum_partial(const void *buff, int len, __wsum sum) { unsigned int result = do_csum(buff, len); /* add in old sum, and carry.. */ result += (__force u32)sum; if ((__force u32)sum > result) result += 1; return (__force __wsum)result; } EXPORT_SYMBOL(csum_partial); /* * copy while checksumming, otherwise like csum_partial */ __wsum csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum 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. */ __wsum csum_partial_copy_from_user (const void *src, void *dst, int len, __wsum 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); }