SH7052 datasheet(52/919 Pages) RENESAS

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2.2

Data Formats

2.2.1

Data Format in Registers

bits) or a word (16 bits), it is sign-extended into a longword when loaded into a register (figure

2.4).

Longword

Figure 2.4 Longword Operand

2.2.2

Data Format in Memory

Memory data formats are classified into bytes, words, and longwords. Byte data can be located at

any address, but word data must begin at address 2n and longword data at address 4n. An address

error will occur if access is attempted beginning at an address other than these boundaries. 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).

Byte

Word

Address 2n

Address 4n

Longword

Address m

Address m + 2

Address m + 1

Address m + 3

Figure 2.5 Byte, Word, and Longword Alignment

2.2.3

Immediate Data Format

Byte (8-bit) immediate data resides in an instruction code. Immediate data accessed by the MOV,

ADD, and CMP/EQ instructions is sign-extended and handled in registers as longword data.

Immediate data accessed by the TST, AND, OR, and XOR instructions is zero-extended and

handled as longword data. Consequently, AND instructions with immediate data always clear the

upper 24 bits of the destination register.

SH7052 Datasheet(PDF) 52 Page - Renesas Technology Corp