MN1030 Просмотр технического описания (PDF) - Unspecified

Номер в каталоге

Компоненты Описание

производитель

MN1030

MICROCOMPUTER

Unspecified 

Expalanation for Code

Sequences to avoid

Description

Pipeline architecture

Example of problematic

program

Example of revised

program

Applicable instructions

Notes

Read carefully to run

the program right

Chapter 3 Usage Notes

(3) Cachable Memory, DCBYPS = 0, Follower Storing without d32/abs32

[ Description ]

High-speed

To prevent pipeline stalls, we recommend inserting at least one cycle when the DCBYPS bit is “0,”

AM31

the leading instruction accesses cachable external memory, and the following instruction stores the

data without using a d32 or abs32 operand.

AM32

DEC

EX

MEM

WB

load

cache data

available

1cycle gap

Store instruction

without 32-bit immediate value

instruction decoding

calculation

instruction

decoding

calculation

cache access

cache access

cache readout/

alignment/extension

of memory data/

register write

cache readout

complete

write cache

readout-data

[ Example ]

[ Problematic Version ]

inc

a1

mov

(a0),d0

mov

d0,(a1)

Load instruction

Instruction storing loaded data without d32/abs32 operand

Retrieving and aligning the data from the cache takes one cycle, so the pipeline stalls

until the data loaded with the first MOV instruction is available to the second MOV

instruction.

[ Revised Version ]

mov

inc

mov

(a0),d0

a1

d0,(a1)

Load instruction

Instruction storing loaded data without d32/abs32 operand

The data loaded with the first MOV instruction is available to the second MOV instruc-

tion, so the pipeline does not stall.

[ Applicable Instructions ]

<Leading instruction>

<Following instruction>

All load variants of MOV, MOVBU, and MOVHU

MOV, MOVBU, MOVB, MOVHU, and MOVH store without d32/abs32

operands

Here cachable external memory refers to the cachable portions of AM31 or AM32

external memory.

Code Sequences to Avoid 131

< About This Manual - 5 >

Share Link: