linux / linux / kernel / git / torvalds / linux / refs/tags/v2.6.13-rc2 / . / arch / ia64 / lib / checksum.c

/* | |

* Network checksum routines | |

* | |

* Copyright (C) 1999, 2003 Hewlett-Packard Co | |

* Stephane Eranian <eranian@hpl.hp.com> | |

* | |

* Most of the code coming from arch/alpha/lib/checksum.c | |

* | |

* This file contains network checksum routines that are better done | |

* in an architecture-specific manner due to speed.. | |

*/ | |

#include <linux/module.h> | |

#include <linux/string.h> | |

#include <asm/byteorder.h> | |

static inline unsigned short | |

from64to16 (unsigned long x) | |

{ | |

/* add up 32-bit words for 33 bits */ | |

x = (x & 0xffffffff) + (x >> 32); | |

/* add up 16-bit and 17-bit words for 17+c bits */ | |

x = (x & 0xffff) + (x >> 16); | |

/* add up 16-bit and 2-bit for 16+c bit */ | |

x = (x & 0xffff) + (x >> 16); | |

/* add up carry.. */ | |

x = (x & 0xffff) + (x >> 16); | |

return x; | |

} | |

/* | |

* computes the checksum of the TCP/UDP pseudo-header | |

* returns a 16-bit checksum, already complemented. | |

*/ | |

unsigned short int | |

csum_tcpudp_magic (unsigned long saddr, unsigned long daddr, unsigned short len, | |

unsigned short proto, unsigned int sum) | |

{ | |

return ~from64to16(saddr + daddr + sum + ((unsigned long) ntohs(len) << 16) + | |

((unsigned long) proto << 8)); | |

} | |

EXPORT_SYMBOL(csum_tcpudp_magic); | |

unsigned int | |

csum_tcpudp_nofold (unsigned long saddr, unsigned long daddr, unsigned short len, | |

unsigned short proto, unsigned int sum) | |

{ | |

unsigned long result; | |

result = (saddr + daddr + sum + | |

((unsigned long) ntohs(len) << 16) + | |

((unsigned long) proto << 8)); | |

/* Fold down to 32-bits so we don't lose in the typedef-less network stack. */ | |

/* 64 to 33 */ | |

result = (result & 0xffffffff) + (result >> 32); | |

/* 33 to 32 */ | |

result = (result & 0xffffffff) + (result >> 32); | |

return result; | |

} | |

extern unsigned long do_csum (const unsigned char *, long); | |

/* | |

* 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) | |

{ | |

unsigned long result = do_csum(buff, len); | |

/* add in old sum, and carry.. */ | |

result += sum; | |

/* 32+c bits -> 32 bits */ | |

result = (result & 0xffffffff) + (result >> 32); | |

return result; | |

} | |

EXPORT_SYMBOL(csum_partial); | |

/* | |

* this routine is used for miscellaneous IP-like checksums, mainly | |

* in icmp.c | |

*/ | |

unsigned short | |

ip_compute_csum (unsigned char * buff, int len) | |

{ | |

return ~do_csum(buff,len); | |

} | |

EXPORT_SYMBOL(ip_compute_csum); |