| /* |
| * Copyright 2004-2009 Analog Devices Inc. |
| * |
| * Licensed under the GPL-2 or later. |
| * |
| * 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. |
| * |
| */ |
| |
| #include <linux/module.h> |
| #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. |
| */ |
| __sum16 ip_fast_csum(unsigned char *iph, unsigned int ihl) |
| { |
| return (__force __sum16)~do_csum(iph, ihl * 4); |
| } |
| EXPORT_SYMBOL(ip_fast_csum); |
| |
| /* |
| * 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 |
| */ |
| __wsum csum_partial(const void *buff, int len, __wsum 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; |
| } |
| EXPORT_SYMBOL(csum_partial); |
| |
| /* |
| * 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); |
| } |
| EXPORT_SYMBOL(ip_compute_csum); |
| |
| /* |
| * copy from fs while checksumming, otherwise like csum_partial |
| */ |
| |
| __wsum |
| csum_partial_copy_from_user(const void __user *src, void *dst, |
| int len, __wsum sum, int *csum_err) |
| { |
| if (csum_err) |
| *csum_err = 0; |
| memcpy(dst, (__force void *)src, len); |
| return csum_partial(dst, len, sum); |
| } |
| EXPORT_SYMBOL(csum_partial_copy_from_user); |
| |
| /* |
| * copy from ds while checksumming, otherwise like csum_partial |
| */ |
| |
| __wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum) |
| { |
| memcpy(dst, src, len); |
| return csum_partial(dst, len, sum); |
| } |
| EXPORT_SYMBOL(csum_partial_copy); |