给vivi增加tftp下载功能(4)

  做这个vivi的时候，遇到两个问题,不知道是什么原因：

void
NetSetIP(volatile uchar * xip, IPaddr_t dest, int dport, int sport, int len)
{
    volatile IP_t *ip = (IP_t *)xip;

    /*
     *    If the data is an odd number of bytes, zero the
     *    byte after the last byte so that the checksum
     *    will work.
     */
    if (len & 1)
        xip[IP_HDR_SIZE + len] = 0;

    /*
     *    Construct an IP and UDP header.
     *    (need to set no fragment bit - XXX)
     */
    ip->ip_hl_v = 0x45;        /* IP_HDR_SIZE / 4 (not including UDP) */
    ip->ip_tos = 0;
    ip->ip_len = htons(IP_HDR_SIZE + len);
    ip->ip_id = htons(NetIPID++);
    ip->ip_off = htons(0x4000);    /* No fragmentation */
    ip->ip_ttl = 255;
    ip->ip_p = 17;        /* UDP */
    ip->ip_sum = 0;
    NetCopyIP((void*)&ip->ip_src, &NetOurIP); /* already in network byte order */
    NetCopyIP((void*)&ip->ip_dst, &dest);     /* - "" - */
    ip->udp_src = htons(sport);
    ip->udp_dst = htons(dport);
    ip->udp_len = htons(8 + len);
    ip->udp_xsum = 0;
    ip->ip_sum = ~NetCksum((uchar *)ip, IP_HDR_SIZE_NO_UDP / 2);
}

如果这里定义为volatile IP_t *ip = (IP_t *)xip;则运行的时候会卡在这里。去掉volatile限定词即可。。
二：


static __inline__ void
store_block (unsigned block, uchar * src, size_t len)
{    
    ulong offset = block * TftpBlkSize + TftpBlockWrapOffset;
    ulong newsize = offset + len;
    int rc=0;
    rc=write_to_flash(write_addr+offset,len,src,flag);
    if(rc!=0){
        printk("error when write to flash\n");
        NetState = NETLOOP_FAIL;
        return;
    ...


}
}

传递给write_to_flash的参数len的值为512.而当程序进入write_to_flash执行后，len值却不是512,变成了一个很大的数。后来改为：
int to=write_addr+offset;
write_to_flash(to,len,src,flag);
后问题解决..