CHAPTER 31. ENDIANNESS CHAPTER 31. ENDIANNESS

Chapter 31

Endianness

The endianness is a way of representing values in memory.

31.1 Big-endian.

The0x12345678value is represented in memory as:

address in memory byte value

+0 0x12

+1 0x34

+2 0x56

+3 0x78

Big-endian CPUs include Motorola 68k, IBM POWER.

31.2 Little-endian

The0x12345678value is represented in memory as:

address in memory byte value

+0 0x78

+1 0x56

+2 0x34

+3 0x12

Little-endian CPUs include Intel x86.

31.3 Example

Let’s take big-endian MIPS Linux installed and ready in QEMU^1.

And let’s compile this simple example:

#include <stdio.h>

int main()
{
int v, i;

v=123;

printf ("%02X %02X %02X %02X\n",
(char)&v,
(((char)&v)+1),
(((char)&v)+2),
(((char)&v)+3));
};

(^1) Available for download here:http://go.yurichev.com/17008