linux / linux / kernel / git / mellanox / linux / refs/tags/v2.6.24 / . / arch / blackfin / lib / checksum.c

/* | |

* 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); | |

} |