E 和 R 前缀在英特尔 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，64 位寄存器名称以 R 开头.E 和 R 代表什么?选择这些字母有什么理由吗?

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(例如 Windbg)中看到，最右边的位仍然使用与 64 位寄存器相同的名称，除了名称以 E 开头.例如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，为什么注册后缀X?

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

推荐答案

• R 仅代表register".AMD64 ISA 扩展添加了 8 个额外的通用寄存器，命名为 R8 到 R15.原始 8 个寄存器的 64 位扩展版本添加了一个 R 前缀为了对称.

  • 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extended"或enhanced".(维基百科说e扩展".)它们是 16-bit 寄存器，因为它们提供 16 个额外的位，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 也表示extended"——或者它可能意味着 16，就像他的x十进制一样. 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，L 后缀表示低"，H 后缀表示高".

    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，您有 8 位 AL 和 AH 寄存器，它们是 16 位的低字节和高字节AX寄存器，即32位EAX寄存器的低位字，即64位RAX的低位双字注册.

    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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