如何确定目标文件中指令的开始和结束？ [英] How do I determine the start and end of instructions in an object file?

问题描述

因此，我一直在尝试编写模拟器，或者至少了解东西的工作原理。我对汇编语言（尤其是z80和x86）有相当的了解，但是我从来没有真正理解过目标文件（或者我的情况是.gb ROM文件）如何指示指令的开始和结束。

So, I've been trying to write an emulator, or at least understand how stuff works. I have a decent grasp of assembly, particularly z80 and x86, but I've never really understood how an object file (or in my case, a .gb ROM file) indicates the start and end of an instruction.

我正在尝试为每条指令解析操作码，但是我发现这并不像每条指令后都有换行符。那么这是怎么发生的呢？对我来说，它看起来像是一堆字节，无法分辨操作码及其操作数之间的区别。

I'm trying to parse out the opcode for each instruction, but it occurred to me that it's not like there's a line break after every instruction. So how does this happen? To me, it just looks like a bunch of bytes, with no way to tell the difference between an opcode and its operands.

推荐答案

对于大多数CPU-我相信Z80属于此类-指令的长度是隐含的。

For most CPUs - and I believe Z80 falls in this category - the length of an instruction is implicit.

也就是说，您必须对指令进行解码才能弄清楚它有多长。

That is, you must decode the instruction in order to figure out how long it is.

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