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CPU
2.4.2 Data Types
Data types can be processed in the four types of bit, byte, halfword and word data. Byte data, halfword data and
word data can be handled as signed and unsigned data. The sign bit is MSB.
The data in the memory must be aligned data. In other words, the two bits on the LSB side of addresses containing
word data must be "00" (addresses which are a multiple of 4), and the LSB of addresses containing halfword data
must be "0" (addresses which are a multiple of 2).
Byte and bit placement conforms with the Little Endian format. Therefore, the address of the byte data on the MSB
side of halfword data is the LSB side byte data address + 1,and the address of the byte data on the MSB side of word
data is the LSB side byte data address + 3. The bit number for bit data starts at 0 on the LSB and increases towards
the MSB.
(1) Bit data
(2) Byte data
Unsigned 8-bit
Signed 8-bit (sign bit: MSB)
(3) Halfword data
Unsigned 16-bit
Signed 16-bit (sign bit: MSB)
(4) Word data
Unsigned 32-bit
Signed 32-bit (sign bit: MSB)
Table 2-4-2 Data Types
Fig. 2-4-1 Little Endian Format
MSB LSB
Address in the memory
Word data
Bit No. 31 24 23 16 15 8 7 0
4n4n+14n+24n+3
Most significant byte Least significant byte
Upper halfword Lower halfword
Halfword data
Most significant byte Least significant byte
Byte data