Motorola MPC823e

MOTOROLA MPC823e REFERENCE MANUAL 14-1
ENDIAN MODES
14
SECTION 14
ENDIAN MODES
This section will discuss how the MPC823e supports three system endian configurations:
• Little-endian system
• Big-endian system
• PowerPC
™
little-endian system
A general description of the different endian modes can be found in
The PowerPC
Microprocessor Family: The Programming Environments (MPCFPE/AD) manual that is
available from Motorola. Throughout the MPC823e Reference Manual , the term system
refers to the devices that reside on the MPC823e bus. The MPC823e core operates in the
big-endian mode of a big-endian system and in the PowerPC little-endian mode of two other
configurations.
Table 14-2 contains possible programming configurations.
Table 14-1. Little-Endian Effective Address Modification
For Individual Aligned Scalar
DATA LENGTH (BYTES) ADDRESS MODIFICATION
1 XOR with 0b111
2 XOR with 0b110
4 XOR with 0b100
8 (No Change)
NOTE: There are no 8-byte scalars in the MPC823e .
Table 14-2. Endian Mode Programming For Core Data Structures
MODE MSR
LE
(AND MSR
ILE
) DC_CSR
LES
Big-Endian Mode 0 0
Little-Endian Mode 0 1
PowerPC Little-Endian Mode 1 0
Reserved 1 1