Renesas M32R/ECU Series User Manual page 47

2
(2) Data formats in memory
The data sizes in memory can be byte (8 bits), halfword (16 bits) or word (32 bits). Although byte data can
be located at any address, halfword and word data must be located at the addresses aligned with a
halfword boundary (least significant address bit = "0") or a word boundary (two low-order address bits =
"00"), respectively. If an attempt is made to access memory data that overlaps the halfword or word bound-
ary, an address exception occurs.
Byte
Halfword
Word
Figure 2.6.3 Data Formats in Memory
(3) Endian
The diagrams below show a general endian system and the endian adopted for the M32R family of
Mitsubishi microcomputers.
Big endian
Little endian
Note: • Even when bits are arranged in big endian, H'01 is not B'10000000.
Figure 2.6.4 General Endian System
Address
+0 address +1 address
b0 7 8
Byte
Byte
b0
Halfword
b0
Bit endian
(H'01)
B'0000001
b0 b7
B'0000001
b7 b0
2-10
+2 address +3 address
15 16 23 24
Byte
Byte
15
Halfword
Word
Byte endian
(H'01234567)
H'01 H'23
HH HL
H'45
H'67
LL LH
32180 Group User's Manual (Rev.1.0)
CPU
2.6 Data Formats
b31
b31
b31
H'45 H'67
LH LL
H'23 H'01
HL HH