Data Types and Endianness
Data Types and Endianness
MicroBlaze uses Big-Endian, bit-reversed format to represent data. The hardware supported data types for MicroBlaze are word, half word, and byte. The bit and byte organization for each type is shown in the following tables.
Table 1-2:Word Data Type | | | | |
| | | | |
Byte address | n | n+1 | n+2 | n+3 |
| | | | |
Byte label | 0 | 1 | 2 | 3 |
| | | | |
Byte | MSByte | | | LSByte |
significance | | | | |
| | | | |
Bit label | 0 | | | 31 |
| | | | |
Bit significance | MSBit | | | LSBit |
Table 1-3:Half Word Data Type | | | | |
| | | |
| | | | |
Byte address | n | n+1 | | |
| | | | |
Byte label | 0 | 1 | | |
| | | | |
Byte | MSByte | LSByte | | |
significance | | | | |
| | | | |
Bit label | 0 | 15 | | |
| | | | |
Bit significance | MSBit | LSBit | | |
| | | | |
Table 1-4:Byte Data Type
Byte address
Bit label
Bit significance
Instructions
All MicroBlaze instructions are 32 bits and are defined as either Type A or Type B. Type A instructions have up to two source register operands and one destination register operand. Type B instructions have one source register and a 16-bit immediate operand (which can be extended to 32 bits by preceding the Type B instruction with an IMM instruction). Type B instructions have a single destination register operand. Instructions are provided in the following functional categories: arithmetic, logical, branch, load/store, and special. Table 1-6lists the MicroBlaze instruction set. Refer to Chapter 4, “MicroBlaze Instruction Set Architecture”, for more information on these instructions. Table 1-5describes the instruction set nomenclature used in the semantics of each instruction.
MicroBlaze Processor Reference Guide | www.xilinx.com | 13 |
UG081 (v6.0) June 1, 2006 | 1-800-255-7778 | |