SH7046 Datasheet, PDF (57/611 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7046 Series

2.3 Data Formats
Section 2 CPU
2.3.1 Data Format in Registers
Register operands are always longwords (32 bits). If the size of memory operand is a byte (8 bits)
or a word (16 bits), it is changed into a longword by expanding the sign-part when loaded into a
register.
31
0
Longword
Figure 2.2 Data Format in Registers
2.3.2 Data Formats in Memory
Memory data formats are classified into bytes, words, and longwords. Byte data can be accessed
from any address. Locate, however, word data at an address 2n, longword data at 4n. Otherwise,
an address error will occur if an attempt is made to access word data starting from an address other
than 2n or longword data starting from an address other than 4n. In such cases, the data accessed
cannot be guaranteed. The hardware stack area, pointed by the hardware stack pointer (SP, R15),
uses only longword data starting from address 4n because this area holds the program counter and
status register.
Address 2n
Address 4n
Address m + 1
Address m + 3
Address m
Address m + 2
31
23
15
7
0
Byte
Byte
Byte
Byte
Word
Word
Longword
Figure 2.3 Data Formats in Memory
Rev. 4.00 Dec 05, 2005 page 13 of 564
REJ09B0270-0400