[lwip-users] a question about alignment

[jack W]

hi everyone 
      i have defined a non-alignment struct named ip_addr {.....}
and i use the macro IP4_ADDR()  in the file  ip_addr.h to write the ip address 
"192.168.0.3" into  a pointer variable my_addr.  in the netif_add function , 
there is a macoro ip_add_set() . when the  my_addr is put into the macro . the 
result is (192.168.0.1)0x0100A8C0    not (192.168.0.3)0x0300A8C0 . I do not 
know why ?

my struct is following : PACK_STRUCT_BEGIN
                           struct ip_addr{
                          PACK_STRUCT_FIELD(u32_t ip_addr);}
   

and i defined the macro PACK_STRUC_BEGIN __packed 
                 and the macro PACK_STRUCT_FIEL __packed x;


i use the ADS (a METROWERKS CODEWARRIOR ARM DEVELOPMETN SUITE) in the winxp; 
the __packed is the keyword of ads compiler that can define the non-alignment 
struct. 
there is a url of __packed information 
http://www.arm.com/support/faqdev/1228.html