SH7101 datasheet(53/560 Pages) RENESAS

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Section 2 CPU

Rev.1.00 Sep. 18, 2008 Page 19 of 522

REJ09B0069-0100

2.3

Data Formats

2.3.1

Data Format in Registers

or a word (16 bits), it is changed into a longword by expanding the sign-part when loaded into a

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.

Byte

Word

Address 2n

Address 4n

Longword

Address m

Address m + 2

Address m + 1

Address m + 3

Figure 2.3 Data Formats in Memory

2.3.3

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.

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