SH7205 datasheet(84/1904 Pages) RENESAS

84 / 1904 page

Section 2 CPU

Rev. 1.00 Mar. 25, 2008 Page 52 of 1868

REJ09B0372-0100

2.3

Instruction Features

2.3.1

RISC-Type Instruction Set

Instructions are RISC type. This section details their functions.

(1)

16-Bit Fixed-Length Instructions

Basic instructions have a fixed length of 16 bits, improving program code efficiency.

(2)

32-Bit Fixed-Length Instructions

The SH-2A additionally features 32-bit fixed-length instructions, improving performance and ease

of use.

(3)

One Instruction per State

Each basic instruction can be executed in one cycle using the pipeline system.

(4)

Data Length

Longword is the standard data length for all operations. Memory can be accessed in bytes, words,

or longwords. Byte or word data in memory is sign-extended and handled as longword data.

Immediate data is sign-extended for arithmetic operations or zero-extended for logic operations. It

is also handled as longword data.

Table 2.2

Sign Extension of Word Data

SH2-A CPU

Description

Example of Other CPU

MOV.W

@(disp,PC),R1

ADD

R1,R0

.........

.DATA.W

H'1234

Data is sign-extended to 32

bits, and R1 becomes

H'00001234. It is next

operated upon by an ADD

instruction.

ADD.W

#H'1234,R0

Note:

@(disp, PC) accesses the immediate data.

(5)

Load-Store Architecture

Basic operations are executed between registers. For operations that involve memory access, data

is loaded to the registers and executed (load-store architecture). Instructions such as AND that

manipulate bits, however, are executed directly in memory.

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