2017年7月7日 · Registers like eax, ebx, etc are the 32-bit registers which exist both in the original 32-bit x86 ISA, as well as the 64-bit x86-64. If your book refers only to those registers, it is likely that it doesn't cover the 64-bit extension (perhaps it was written before it).

2016年12月20日 · mov (%rax), %eax # AT&T syntax or, equivalently in Intel syntax: mov eax, DWORD PTR [rax] ; Intel syntax dereferences the memory address stored in rax, reads a 32-bit value from that memory address, and stores it in the eax register.

In particular, the notion of the processor registers does not match reality, there is no such thing as a EAX or RAX register. One primary job of the instruction decoder is to convert the legacy x86/x64 instructions into micro-ops, instructions of a RISC-like processor.

With the advent of x64 and 64-bit architecture, register size doubled once again and the EAX register was renamed RAX. However a new naming convention was also adopted, and the RAX register is also known as the R0 register:

2021年10月8日 · 累加寄存器 (eax / rax) eax是32位累加寄存器，rax是它的64位扩展版本。 常用于算术运算和函数返回值。 基址寄存器 (ebx / rbx) ebx是32位基址寄存器，rbx是它的64位扩展版本。 通常用作基址指针，但在现代编程中用途较少固定。

Like C++ variables, registers are actually available in several sizes: rax is the 64-bit, "long" size register. It was added in 2003 during the transition to 64-bit processors. eax is the 32-bit, "int" size register. It was added in 1985 during the transition to 32-bit processors with the 80386 CPU.

2019年8月27日 · EAX 是"累加器" (accumulator), 它是很多加法乘法指令的缺省寄存器。 EBX 是"基地址" (base)寄存器, 在内存寻址时存放基地址。 ECX 是计数器 (counter), 是重复 (REP)前缀指令和LOOP指令的内定计数器。 EDX 则总是被用来放整数除法产生的余数。 ESI/EDI分别叫做"源/目标索引寄存器" (source/destination index),因为在很多字符串操作指令中, DS:ESI指向源串,而ES:EDI指向目标串. EBP是"基址指针" (BASE POINTER), 它最经常被用作高级语言函数调用 …

2020年1月31日 · 1.对32位寄存器的写操作和运算操作，则会对相应的64位寄存器的高32位清零。 如在x64dbg上实验，mov eax, 1和add eax, 1会使rax的高32位清零； xor eax, eax是对eax的清零运算操作，所以xor rax, rax会被编译器优化为指令更短的xor eax, eax因为二者在x64汇编中的效果是一样的； 但是mov ax,1和mov al, 1不会对rax的高32位进行清零的操作。 2.立即数的使用，优先使用32位扩展，64位的立即数使用较少。 push指令和对内存的写操作只支持4字节的立即数 …

以 r 开头的寄存器，如 rax 、 rbx 等，是使用 AMD64扩展 引入的 64位 寄存器，对现有32位x86 ISA进行了扩展。 后来，英特尔采用了这种ISA扩展，并常被称为更中性的名称 x86-64。 从AMD和英特尔在过去十年发布的几乎所有x86芯片都支持此ISA。 像 eax 、 ebx 等的寄存器是32位寄存器，既存在于原始的32位x86 ISA中，也存在于64位x86-64中。 如果你的书籍只提到这些寄存器，很可能它没有涵盖64位扩展（可能是在其出版之前编写的）。 请注意，32位和64位寄存器不是 …

2024年12月11日 · For example, the 64-bit extension of eax is called rax. The new registers are named r8 through r15. The lower 32 bits, 16 bits, and 8 bits of each register are directly addressable in operands. This includes registers, like esi, …