Dave Angel wrote:
Little-endian is the method used by the Intel processor (such as the
Pentium). Big-endian is the system used by most network protocols, as
well as the 68000 and many other processors.
There used to be mainframes with various forms of middle-endian layouts.
Fortunately they are no longer around.
http://www.retrologic.com/jargon/M/middle-endian.html
For our purposes, it's the ordering of the bytes within a 16 or 32 bit
number. Little-endian puts the least significant byte first, while
big-endian puts the most significant byte first.
In this context, least significant and most significant may need explaining.
In decimal numbers, we write one hundred and twenty-three as 123. The 1
is most significant, because it represents 1 HUNDRED rather than 1 UNIT.
And similarly the 3 is least significant. So numbers using Arabic
numerals are big-endian.
The same applies for computer integers. 123 written in hexadecimal is
7B, which of course is big-endian just like decimal. But when storing
this number in memory, we have a choice: we can store it in big-endian
format, just like we write it: 7B, where the 7 is the "left-most"
(lowest address) number. Or we can store it in little-endian format, B7,
where the 7 has the higher address, and read from right-to-left.
And of course, bytes themselves can be either little-endian or
big-endian, *independently* of byte ordering within larger units.
http://en.wikipedia.org/wiki/Endianness
http://en.wikipedia.org/wiki/Bit_numbering
--
Steven
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