>>> Also, I suggest to avoid the terms "left" and "right", since I >>> encountered various occasions where they caused more confusion than they >>> helped. And the term "most significant" can not generally be applied to >>> registers either, so in this case I'd prefer something like "located in >>> the lowest-addressed bytes of the register when stored in memory". >> >> I've not found this to be true. > > Really? I usually refer to lower- and higher-addressed memory units by > "left" and "right", respectively. However, all diagrams in the Intel 64 > and IA-32 architectures have this reversed and show lower addresses > below/right and higher addresses above/left. Similarly, when referring > to the bytes in a register I'd call the lower- and higher-addressed > bytes (in natural memory representation) "left" and "right", > respectively. But at least for integer registers some people call the > most significant bytes "left", independently from byte ordering. I had > a lengthy discussion with Jian Xu, where one of our misunderstandings > was centered around the definition of "left" and "right". How do you > interpret these terms?
I've been guilty of using "left" and "right", and been called out on it, even when the context was referring simply to bits within a byte or within a register. I thought they'd be unambiguous in that context, but they do seem to cause uncertainty, probably for the very reason that some little-endian diagrams will depict bytes forming a larger unit from right-to-left. Instead, I now try to stick with "most-significant" and "least-significant" when talking about bits within a larger unit, or bytes within a word, which should always be unambiguous. I really don't see how those terms could lead to any uncertainty. When talking about bytes in memory, I try to use "lower address" and "higher address". I would, however, avoid referring to bytes within a register. It would be better to talk about how a byte in memory is placed in the register, and it should be clear to say something like "a byte is loaded into the least-significant bits of the register." -cary _______________________________________________ Dwarf-Discuss mailing list Dwarf-Discuss@lists.dwarfstd.org http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org
