Hi Fabi, have you followed this guide
http://lwip.wikia.com/wiki/Porting_for_an_OS ? In particular:
Packet headers data is stored in network byte order
http://en.wikipedia.org/wiki/Endianness#Endianness_in_networking which is
the the big-endian mode http://en.wikipedia.org/wiki/Endianness#Big-endian.
If your processor architure is little-endian
http://en.wikipedia.org/wiki/Endianness#Little-endian, then we need to
convert data using htons()/htonl()/ntohs()/ntohl()
http://www.opengroup.org/onlinepubs/007908799/xns/htonl.html functions.
Here an example (the following code use CMSIS, so you must be sure to have
it enabled)
---
u16_t
lwip_le_htons(u16_t n)
{
return ((n 0xff) 8) | ((n 0xff00) 8);
}
/**
* Convert an u16_t from network- to host byte order.
*
* @param n u16_t in network byte order
* @return n in host byte order
*/
u16_t
lwip_le_ntohs(u16_t n)
{
return ((n 0xff) 8) | ((n 0xff00) 8);
}
/**
* Convert an u32_t from host- to network byte order.
*
* @param n u32_t in host byte order
* @return n in network byte order
*/
u32_t
lwip_le_htonl(u32_t n)
{
return __REV(n);
}
/**
* Convert an u32_t from network- to host byte order.
*
* @param n u32_t in network byte order
* @return n in host byte order
*/
u32_t
lwip_le_ntohl(u32_t n)
{
return __REV(n);
}
---
you must insert these functions in /core/def.c and check the #define chain
Bye Adriano
2014-06-26 11:14 GMT+02:00 Fabian Cenedese cened...@indel.ch:
Hi
I'm using lwip 1.4.1 on big endian targets and it works. Now I
want to use the same software on little endian targets (ARM)
and have problems. Should that work from the lwip part? The
Ethernet frame of course is always big endian why it works
without problems on big endian targets. However I'm not sure
that all places do the correct conversion between host and
network order.
E.g. the IP address for the interface:
IP4_ADDR(ipaddr, 192, 168, 1, 197)
netif_add(m_Netif, ipaddr...
gives a debug trace
... set to 197.1.168.192
Is the trace wrong or did I give a wrong address?
Sending (e.g. ARP reply):
ip_output_if_opt
The ip address is copied directly into the frame:
ip_addr_copy(iphdr-src, *src);
Shouldn't that be
ip_addr_set_hton(iphdr-src, src);
if the runnig hardware is little endian?
And yes, I do have
#define BYTE_ORDER LITTLE_ENDIAN
Thanks
bye Fabi
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Adriano Pallavicino
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