On Tuesday 11 of December 2012 09:12:09 Holmes.Sherlock wrote: > Paweł Sikora-2 wrote > > iirc, the C language gives no guarantee of the ordering of fields within > > machine words, > > so if you use them for the h/w register modeling, you program will not > > only be nonportable, > > it will be compiler-dependent too. you should really read suitable > > byte/word/doubleword > > from mapped h/w memory, convert it with le/be_to_cpu() method and > > shift/mask to access bits. > > But here __attribute__ ((__packed__)) has been used. Doesn't it have any > effect? Or are we missing out the ordering compiler is enforcing? gcc's 'packed' attribute is related to the memory usage only. ordering is still compiler specific. > Isn't it surprising that on Little Endian system the ordering is as we expect, > while in Big-Endian system, no apparent correlation is being found? nothing should be surprising in the times when ARM cores could work in both modes :) btw. there's a thread about different ordering @ http://gcc.gnu.org/ml/gcc/2012-10/msg00016.html
