SH7050 Datasheet, PDF (44/841 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperH RISC engine Family/

Section 2 CPU
2.2 Data Formats
2.2.1 Data Format in Registers
Register operands are always longwords (32 bits). When the memory operand is only a byte (8
bits) or a word (16 bits), it is sign-extended into a longword when loaded into a register (figure
2.4).
31
0
Longword
Figure 2.4 Data Format in Registers
2.2.2 Data Format in Memory
Memory data formats are classified into bytes, words, and longwords. Byte data can be accessed
from any address, but an address error will occur if you try 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, referred to 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 (figure 2.5).
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 2.5 Data Format in Memory
Rev. 5.00 Jan 06, 2006 page 24 of 818
REJ09B0273-0500