Little endian - Revision history

80.145.152.119 at 11:49, 4 March 2006

2006-03-04T11:49:00Z

Thedude0001: =Example= typo

2005-03-15T12:28:57Z

=Example= typo

Jacobo221 at 01:16, 10 March 2005

2005-03-10T01:16:36Z

Jacobo221 at 01:16, 10 March 2005

2005-03-10T01:16:21Z

80.224.220.139 at 20:49, 9 March 2005

2005-03-09T20:49:47Z

New page

== Introduction to [[endian]]ness ==

Having read the [[endian]]ness article, you might already have an idea of what this is for.

The [[endian]]ess defines the bytes' order in physical memory.

== Definition ==

When you must store a two-bytes (or larger) value in memory, you can either store the first byte(s) in the first place or the second byte(s) in the first place.

Little [[endian]] defines that the first bytes will go first.

== Example ==

An example of a two-bytes number is 65534. This number requires two bytes to be stored in memory. The decimal number 65534 is represented, in hexadecimal, as FFFE (or 0xFFFE). Here we can see the two byes: FF and FE.

We can decide wether we want to place the FF byte first in memory or the FE byte first.

Little [[endian]] tells us to place first the which whose numbers have less weight in the total number. That is FF, since FE here represents 254, while FF represents 65280.

So, physically in memory we would have:

_________________________
Memory Graph: |_____FE_____|_____FF_____|
Memory Possitions: 000001 000002

== Uses ==

This [[endian]]ness is used (amongst others) in machines.

== Notes ==

To understand better the little [[endian]] concept it is helpful to compare it to the [[big endian]] concept.

@@ Line 17: / Line 17: @@
 We can decide wether we want to place the FF byte first in memory or the FE byte first.
-Little [[endian]] tells us to place first the which whose numbers have less weight in the total number. That is FF, since FE here represents 254, while FF represents 65280.
+Little [[endian]] tells us to place first the which whose numbers have less weight in the total number. That is FE, since FE here represents 254, while FF represents 65280.
 So, physically in memory we would have:

@@ Line 13: / Line 13: @@
 == Example ==
-An example of a two-bytes number is 65534. This number requires two bytes to be stored in memory. The decimal number 65534 is represented, in hexadecimal, as FFFE (or 0xFFFE). Here we can see the two byes: FF and FE.
+An example of a two-bytes number is 65534. This number requires two bytes to be stored in memory. The decimal number 65534 is represented, in hexadecimal, as FFFE (or 0xFFFE). Here we can see the two bytes: FF and FE.
 We can decide wether we want to place the FF byte first in memory or the FE byte first.

@@ Line 27: / Line 27: @@
 == Uses ==
-This [[endian]]ness is used (amongst others) in [http://www.intel.com x86], in [http://www.x86-64.org AMD64] and in  [http://h18002.www1.hp.com/alphaserver/vax VAX] machines.
+This [[endian]]ness is used (amongst others) in [http://www.intel.com x86], in [http://www.x86-64.org AMD64] and in [http://h18002.www1.hp.com/alphaserver/vax VAX] machines.
 == Notes ==
 To understand better the little [[endian]] concept it is helpful to compare it to the [[big endian]] concept.