Summary edit

Explanation edit

Here is an example of using the image:

Big endian edit

In Big-Endian: Say you would want to:

• write "0x12345678" 32 bit into memory at addr "0"
• read back 16 bit from address "2"

You would take the parts of the diagram for 32 bit and Big-Endian:

 Value in register:
 81234561
  A B C D  

 Register:
 |------->
  A B C D  32 bit access

 Memory:
 | A B C D  32 bit access address 0
 ---------
   0 1 2 3
   ^
   |-> map 0 here
   A B C D  

 Result in memory: 
 | 12345678  
 ---------
   0 1 2 3
   

Now you would want to read back 16 bit from address "2" in Big-Endian: Then you would use:

 Value in memory: 
 | 12345678  
 ---------
   0 1 2 3

 Memory:
 | A B C D  16 bit access 2
 ---------
   0 1 2 3
       ^
       |-> map 2 here
       |--->
       C D  

 Register:
    |-->|
 A B C D  16 bit access 

 Result in register: 
 | 00005678  
 ---------
   0 1 2 3

Little endian edit

In Little-Endian: Say you would want to :

• write your "0x12345678" 32 bit into memory at addr "0"
• read back 16 bit from address "2"

You would take the parts of the diagram for 32 bit and Little-Endian:

 Value in register:
 12345678
  A B C D  

 Register:
  A B C D  32 bit access
 <-------

 Memory:
  A B C D |  32 bit access 0
 ---------
  3 2 1 0
        ^
      <-| map 0 here
  A B C D  

 Result in memory: 
  12345678|  
 ---------
   3 2 1 0
   

Now you would want to read back 16 bit from address "2" in Little-Endian: Then you would use:

 Value in memory: 
  12345678 |
 -----------
   3 2 1 0

 Memory:
  A B C D |  32 bit access address 2
 ---------
  3 2 1 0
    ^
  <-| map 2 here
  C D  

 Register:
 A B C D  16 bit access
    |<--|

 Result in register: 
  00001234  
 ---------
   3 2 1 0

Licensing edit

Konrad Eisele, the copyright holder of this work, hereby publishes it under the following licenses:

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.http://www.gnu.org/copyleft/fdl.htmlGFDLGNU Free Documentation Licensetruetrue

	This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
	Attribution: Konrad Eisele
	You are free: to share – to copy, distribute and transmit the work to remix – to adapt the work Under the following conditions: attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
	This licensing tag was added to this file as part of the GFDL licensing update.http://creativecommons.org/licenses/by-sa/3.0/CC BY-SA 3.0Creative Commons Attribution-Share Alike 3.0truetrue

This file is licensed under the Creative Commons Attribution-Share Alike 2.5 Generic, 2.0 Generic and 1.0 Generic license.

Attribution: Konrad Eisele

You are free:

• to share – to copy, distribute and transmit the work
• to remix – to adapt the work

Under the following conditions:

• attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
• share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.

https://creativecommons.org/licenses/by-sa/2.5CC BY-SA 2.5 Creative Commons Attribution-Share Alike 2.5 truetrue

You may select the license of your choice.