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CPU如何区分REP和REPE指令？

[英]How does CPU differentiate REP and REPE instructions?

 原文  2015-06-24 13:11:49  0   1    assembly/ x86

问题描述

According to this manual, REP and REPE instructions have different behaviour, but the same opcode F3 . 根据本手册， REP和REPE指令具有不同的行为，但操作码F3相同。

How does CPU differentiate this two commands, if they both have the same opcode? 如果两个命令都具有相同的操作码，CPU如何区分这两个命令？

1 个解决方案

解决方案1
 5 已采纳  2015-06-24 13:14:50

REP and REPE are prefixes , not instructions. REP和REPE是前缀 ，而不是指令。 Some instructions accept the REPE prefix. 一些指令接受REPE前缀。 Others accept REP . 其他人接受REP 。 The ISA was designed so that no instruction accepts both, so the problem does not arise. ISA的设计使任何指令都不能接受两者，因此不会出现问题。

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