uip_arch.c

基于STC单片机与MICROCHIP ENC28J60的TCPIP以太网控制器

/*
 * Copyright (c) 2001, Adam Dunkels.
 * All rights reserved. 
 *
 *
 * This file is part of the uIP TCP/IP stack.
 *
 * $Id: uip_arch.c,v 1.2.2.1 2003/10/04 22:54:17 adam Exp $
 *
 */



#include "uip.h"
#include "uip_arch.h"

#define BUF ((uip_tcpip_hdr *)&uip_buf[UIP_LLH_LEN])
#define IP_PROTO_TCP    6

/*----------------------------------------------------------------------------*/
void
uip_add32(u8_t *op32, u16_t op16)		//产生一随机序列
{
  
  uip_acc32[3] = op32[3] + (op16 & 0xff);
  uip_acc32[2] = op32[2] + (op16 >> 8);
  uip_acc32[1] = op32[1];
  uip_acc32[0] = op32[0];				//高位
  
  if(uip_acc32[2] < (op16 >> 8)) {
    ++uip_acc32[1];    
    if(uip_acc32[1] == 0) {
      ++uip_acc32[0];
    }
  }
  
  
  if(uip_acc32[3] < (op16 & 0xff)) {
    ++uip_acc32[2];  
    if(uip_acc32[2] == 0) {
      ++uip_acc32[1];    
      if(uip_acc32[1] == 0) {
	++uip_acc32[0];
      }
    }
  }
}
/*-----------------------------------------------------------------------------------*/
u16_t
uip_chksum(u16_t *sdata, u16_t len)			//
{
  u16_t acc;
  
  for(acc = 0; len > 1; len -= 2) {
    acc += *sdata;
    if(acc < *sdata) {
      /* Overflow, so we add the carry to acc (i.e., increase by
         one). */
      ++acc;
    }
    ++sdata;
  }

  /* add up any odd byte */
  if(len == 1) {
    acc += htons(((u16_t)(*(u8_t *)sdata)) << 8);
    if(acc < htons(((u16_t)(*(u8_t *)sdata)) << 8)) {
      ++acc;
    }
  }

  return acc;
}
/*-----------------------------------------------------------------------------------*/
u16_t
uip_ipchksum(void)
{						//如果用ENC28J60的检验和呢？
  return uip_chksum((u16_t *)&uip_buf[UIP_LLH_LEN], 20);
}
/*-----------------------------------------------------------------------------------*/
u16_t
uip_tcpchksum(void)										//BUF->len里面放的长度没有加以太网头
{
  u16_t hsum, sum;

 
  /* Compute the checksum of the TCP header. */
  hsum = uip_chksum((u16_t *)&uip_buf[20 + UIP_LLH_LEN], 20);  //add5

  /* Compute the checksum of the data in the TCP packet and add it to
     the TCP header checksum. */
  sum = uip_chksum((u16_t *)uip_appdata,
		   (u16_t)(((((u16_t)(BUF->len[0]) << 8) + BUF->len[1]) - 40)));		   //add5

  if((sum += hsum) < hsum) {
    ++sum;
  }
  
  if((sum += BUF->srcipaddr[0]) < BUF->srcipaddr[0]) {
    ++sum;
  }
  if((sum += BUF->srcipaddr[1]) < BUF->srcipaddr[1]) {
    ++sum;
  }
  if((sum += BUF->destipaddr[0]) < BUF->destipaddr[0]) {
    ++sum;
  }
  if((sum += BUF->destipaddr[1]) < BUF->destipaddr[1]) {
    ++sum;
  }
  if((sum += (u16_t)htons((u16_t)IP_PROTO_TCP)) < (u16_t)htons((u16_t)IP_PROTO_TCP)) {
    ++sum;
  }

  hsum = (u16_t)htons((((u16_t)(BUF->len[0]) << 8) + BUF->len[1]) - 20);		//减IP头？
  
  if((sum += hsum) < hsum) {
    ++sum;
  }
  
  return sum;
}
/*-----------------------------------------------------------------------------------*/