MicroBlaze Processor Reference Guide www.xilinx.com 13
UG081 (v6.0) June 1, 2006 1-800-255-7778
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.
Instructions
All MicroBlaze instructions are 32 bits and are defined as either Type A or Type B. Type A
instructionshave uptotwosourceregisteroperandsandonedestinationregisteroperand.
TypeBinstructionshave onesourceregisteranda 16-bit immediateoperand(whichcanbe
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 1-6 lists the MicroBlaze instruction set. Refer to Chapter 4, “MicroBlaze Instruction
Set Architecture”, for more information on these instructions. Table 1-5 describes the
instruction set nomenclature used in the semantics of each instruction.
Table 1-2: Word Data Type
Byte address n n+1 n+2 n+3
Byte label 0 1 2 3
Byte
significance
MSByte LSByte
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
significance
MSByte LSByte
Bit label 0 15
Bit significance MSBit LSBit
Table 1-4: Byte Data Type
Byte address n
Bit label 0 7
Bit significance MSBit LSBit