microudp: fix udp txlen

* the preample length 8 is already included in sizeof(struct
ethernet_header)
* the minimum packet size is 64, exluding fcs and including
preample it is 68 (the arp functions are correct)

diff --git a/software/libnet/microudp.c b/software/libnet/microudp.c
index 31bb5aaeb6e3ca19e7c8963c2a0d754cec5dd5a0..d499d63924f9a6f2505e85531e0a4af64dda5255 100644 (file)
--- a/software/libnet/microudp.c
+++ b/software/libnet/microudp.c
@@ -262,8 +262,8 @@ int microudp_send(unsigned short src_port, unsigned short dst_port, unsigned int
                && (cached_mac[3] == 0) && (cached_mac[4] == 0) && (cached_mac[5] == 0))
                return 0;
 
-       txlen = length + sizeof(struct ethernet_header) + sizeof(struct udp_frame) + 8;
-       if(txlen < 72) txlen = 72;
+       txlen = length + sizeof(struct ethernet_header) + sizeof(struct udp_frame);
+       if(txlen < 68) txlen = 68;
        
        fill_eth_header(&txbuffer->frame.eth_header,
                cached_mac,