Data Types and Endianness

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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

n

07

MSBit LSBit

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

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UG081 (v6.0) June 1, 2006

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Xilinx EDK 8.2i manual Data Types and Endianness, Instructions