/* cksumLib.c - checksum routine *//* Copyright 1992-2001 Wind River Systems, Inc. *//*modification history--------------------01d,15oct01,rae  merged from truestack version 01d (SPRs 30521, 64231, 67304)01c,19oct00,rae  fixed error with little endian targets and odd packet sizes                 (spr# 30521)01b,04jul92,smb  added everything above sys/types.h01a,23mar92,jmm  taken from net source  *//*DESCRIPTION*/#include "vxWorks.h"#include "sys/types.h"/********************************************************************************* checksum - portable internet checksum calculation routine** This checksums the buffer <pAddr> of length <len>.  This routine differs* from the standard checksum algorithm (in_cksum) in that it checksums a buffer* while the other checksums an mbuf chain.  For of a description of the* internet checksum algorithm, please refer to RFC 1071.** RETURNS: checksum** NOMANUAL*/u_short checksum    (    u_short *           pAddr,                  /* pointer to buffer  */    int                 len                     /* length of buffer   */    )    {    int         nLeft   = len;    int         sum     = 0;    u_short *   w       = pAddr;    u_short     answer;    while (nLeft > 1)        {        sum     += *w++;        nLeft   -= 2;        }    if (nLeft == 1)#if _BYTE_ORDER == _BIG_ENDIAN        sum += 0 | ((*(u_char *) w) << 8);#else        sum += *(u_char *) w;#endif    sum = (sum >> 16) + (sum & 0xffff);    sum += (sum >> 16);    answer = sum;    return (~answer & 0xffff);    }