什么是＆QUOT; EU＆QUOT;在x86架构？ （计算有效地址？） [英] What is the "EU" in x86 architecture? (calculates effective address?)

问题描述

我读的地方，在x86指令有效地址（如LEA指令）通过计算得出的欧盟。什么是欧盟？究竟是什么参与计算的有效地址？

I read somewhere that effective addresses (as in the LEA instruction) in x86 instructions are calculated by the "EU." What is the EU? What is involved exactly in calculating an effective address?

我只了解了MC68K指令集（UC博尔德教这首），我不能找到一个很好的的x86网页直通谷歌= /。

I've only learned about the MC68k instruction set (UC Boulder teaches this first) and I can't find a good x86 webpage thru google =/ .

谢谢！

推荐答案

英特尔自己的软件开发人员手册是对x86的信息的良好来源，虽然他们可能是矫枉过正位（和更多的参考样，而不是教程等等）。

Intel's own Software Developer's Manuals are a good source of information on the x86, though they may be bit of an overkill (and are more reference-like rather than tutorial-like).

欧盟（执行单元）参考是最有可能在相反的ALU（算术逻辑单元），这是通常负责算术和逻辑指令的处理器的一部分。但是，欧盟已经（或有）算术能力，以及用于计算内存地址。 X86的LEA指令传达这些功能来汇编编程人员。

The EU (Execution Unit) reference was most likely in contrast to ALU (Arithmetic Logic Unit) which is usually the part of the processor responsible for arithmetic and logic instructions. However, the EU has (or had) some arithmetic capabilities as well, for calculating memory addresses. The x86 LEA instruction conveys these capabilities to the assembly programmer.

通常你可以提供一些pretty复杂的内存地址的x86指令：

Normally you can supply some pretty complex memory addresses to an x86 instruction:

sub eax, [eax + ebx*4 + 0042]

和，而ALU处理的算术减法，欧盟负责产生的地址。

and while the ALU handles the arithmetic subtraction, the EU is responsible for generating the address.

通过LEA，可以利用有限的地址生成功能用于其他用途：

With LEA, you can use the limited address-generating capabilities for other purposes:

lea ebx, [eax + ebx*4 + 0042]

比较：

mul ebx, 4
add ebx, eax
add ebx, 0042

我的链接页面上的1卷有节3.7.5张一兵同志商榷的寻址模式 - 什么样的内存地址，你可以提供一个指令期待一个内存操作数（其中LEA就是其中之一），反映什么样的算术欧盟（或任何存储接口部分被称为）是可以胜任的。

"Volume 1" on the page I've linked has a section "3.7.5" dicussing addressing modes - what kind of memory addresses you can supply to an instruction expecting a memory operand (of which LEA is one), reflecting what kind of arithmetic the EU (or whatever the memory interface part is called) is capable of.

卷2是指令集，对所有指令的权威信息，包括LEA。

"Volume 2" is the instruction set reference and has definitive information on all instructions, including LEA.

这篇关于什么是＆QUOT; EU＆QUOT;在x86架构？ （计算有效地址？）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！