E和R前缀在Intel 32位和64位寄存器的名称中代表什么？

问题描述

32位寄存器名称以E开头，而64位寄存器名称以R开头。E和R代表什么？

The 32-bit register names start with an E and the 64-bit ones start with an R. What do the E and R stand for? Is there a reason for choosing these alphabets?

此外，在64位寄存器中，我们也可以在任何低级调试器（如Windbg）中看到正确的-除名称以E开头外，大多数位仍使用与64位寄存器相同的名称来引用。在64位系统中，RAX寄存器最右边的32位称为EAX。

Also, in 64-bit registers, too, we can see in any low-level debugger such as Windbg that the right-most bits are still referred to by the same name as that of the 64-bit register except the name starts with an E. For e.g. the right-most 32 bits of the RAX register in a 64-bit system is referred to as EAX.

那么，E和R代表什么吗？还有，为什么要使用后缀X进行注册？

So, do the E and R stand for something? And also, why the suffix X for register?

推荐答案

• 。 AMD64 ISA扩展增加了8个其他通用寄存器，分别通过 R15 命名为 R8 。原始8个寄存器的64位扩展版本在其上添加了 R 前缀。

  • R just stands for "register". The AMD64 ISA extension added 8 additional general-purpose registers, named R8 through R15. The 64-bit extended versions of the original 8 registers had an R prefix added to them for symmetry.

    E 代表 e xtended或 e 增强。 （。）它们是16个版本的扩展版本。位寄存器，因为它们提供了16个附加位，总共32位。

    E stands for "extended" or "enhanced". (Wikipedia says "extended".) They are the "extended" versions of the 16-bit registers, in that they offer 16 additional bits for 32 bits total.

    X 也是表示 e x 或 16，如he x 十进制。 X 后缀的寄存器是8位寄存器的16位扩展版本。对于8位寄存器，后缀 L 表示低，后缀 H 表示高。 / p>

  
  

  X is also for "extended"—or perhaps it implies 16 as in hexadecimal. The X-suffixed registers are the 16-bit extended versions of the 8-bit registers. For 8-bit registers, the L suffix means "low", and the H suffix means "high".

  因此，以一个特定的寄存器为例，您具有8位的 AL 和 AH 寄存器，它们是16位 AX 寄存器的低字节和高字节，它是32位 EAX 寄存器的低位字，它是64位 RAX 注册。

  Therefore, taking one particular register as an example, you have the 8-bit AL and AH registers, which are the low and high bytes of the 16-bit AX register, which is the low word of the 32-bit EAX register, which is the low double-word of the 64-bit RAX register.

  | 63 - 32 | 31 - 16 | 15 - 8 | 7 - 0 |
  ======================================
  .         .         | AH     | AL    |
  .         .         | AX             |
  .         | EAX                      | 
  | RAX                                |
  ======================================
  | 63 - 32 | 31 - 16 | 15 - 8 | 7 - 0 |
  

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