On 02/04/2020 21:25, J. Gareth Moreton wrote: > Am I right in thinking that, for C alignment, each field is aligned > according to its data size? For example, if you had: > > TType = record > Field1: Byte > Field2: LongInt; > end; > > Are there are three unused bytes between Field1 and Field2 and the > structure as a whole is 8 bytes long and aligned to a 4-byte boundary?
On most platforms, yes. Probably not on 16 bit platforms. > I'm trying to find the page that explains all that, and also exceptional > cases where the data size is not necessary the same as the minimum > alignment. "C alignment" is actually a bad name. It's in fact the ABI alignment (which is indeed what C uses), and hence this is different depending on architecture and OS. As a result, there is no page that explains it all, since you have to look it up in the ABI documentation of every individual platform. Some examples of non-matching alignments on Darwin/i386: * double is aligned to 4 bytes * extended is aligned to 16 bytes Jonas _______________________________________________ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
