Hi Mirek, > Doubles and long long are 8 bytes long but the byte order differs > on my host linux Intel PC from this what I have on the target > linux ppc 405.
That would be due to the difference in endianness of the processors. http://en.wikipedia.org/wiki/Endianness If you want to work on data on both an Intel machine, and a PowerPC, then you have to transfer the data between the machines using a machine-independent binary format. There are several around: 1. Network byte order = big-endian. 2. XDR http://en.wikipedia.org/wiki/External_Data_Representation used by NFS, 3. Common Data Representation http://en.wikipedia.org/wiki/Common_Data_Representation Which is implemented in the ACE C++ library. The nice thing about CDR is that the 'reader makes right', so its only when the endianness of the reader is different that it has to use CPU cycles to reformat the data. Its not only processors that have subtle endian issues. I use little-endian x86 host CPUs in a little-endian PCI backplane talking to big-endian PowerPC processors. Data transferred between the processors is first encoded into a CDR data stream and then decoded. I write binary data files using the same stream formatters, and then use mex routines written in C++ to pull the data into MATLAB data structures. MATLAB data files are also an example of a machine independent binary format. But I don't use them. Cheers, Dave _______________________________________________ Linuxppc-embedded mailing list Linuxppc-embedded@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-embedded
