x86 寄存器

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X86家族CPU寄存器介绍。

x86家族CPU寄存器比较少，整理起来也比较方便，但是他们仍然可以分门别类，
现整理如下。

通用寄存器(general registers)

按照位数的不同，通用寄存器进一步分为8位、16位、32位通用寄存器，

32 bits: EAX, EBX, ECX, EDX
16 bits: AX, BX, CX, DX
8 bits: AH AL, BH BL, CH CL, DH DL

其中，”E”表示extended，”H”表示high byte，”L”表示low byte。
A、B、C、D四组通用寄存器其实也是有自己的专长的，而不仅仅是按照字母顺序命名而已，

EAX, AX, AH, AL:
Accumulator register，它们用于I/O port access, arithmetic, interrupt calls etc.
EBX, BX, BH, BL:
Base register，它们被当做base pointer for memory access
ECX, CX, CH, CL:
Counter register，它们被当做loop counter and for shifts
EDX, DX, DH, DL:
Data register，它们用于I/O port access, arithmetic, some interrupt etc.

段寄存器(segment registers)

CS: code segment
DS: data segment
ES, FS, GS: extra segment. 用于far pointer addressing like video memory and such
SS: stack segment

索引和指针寄存器(index and pointers)

ES:EDI, EDI, DI:
Destination index register. Used for string, memory array copying and setting
and for far pointer addressing with ES

DS:ESI, EDI, SI:
Source index register. Used for string and memory array copying

SS:EBP, EBP, BP:
Stack Base pointer register. Holds the base address of the stack

SS:ESP, ESP, SP:
Stack pointer register. Holds the top address of the stack

CS:EIP, EIP, IP:
Index Pointer. Holds the offset of the next instruction. It can only be read

标志位寄存器(flag register)

标志位寄存器只有一个: EFLAGS，各个bit的含义如下，

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
/*
Bit   Label    Desciption
---------------------------
0      CF      Carry flag
2      PF      Parity flag
4      AF      Auxiliary carry flag
6      ZF      Zero flag
7      SF      Sign flag
8      TF      Trap flag
9      IF      Interrupt enable flag
10     DF      Direction flag
11     OF      Overflow flag
12-13  IOPL    I/O Priviledge level
14     NT      Nested task flag
16     RF      Resume flag
17     VM      Virtual 8086 mode flag
18     AC      Alignment check flag (486+)
19     VIF     Virutal interrupt flag
20     VIP     Virtual interrupt pending flag
21     ID      ID flag

Those that are not listed are reserved by Intel.
 */

控制寄存器(controll registers)

CR0: 开启/关闭 保护模式
CR1:
CR2:
CR3:
CR4:

调试寄存器(debug registers)

DR0 ~ DR7

测试寄存器(test registers)

TR3 ~ TR7

其他寄存器

GDTR: Global Descriptor Table Register
LDTR: Local Descriptor Table Register
IDTR: Interrupt Descriptor Table Register
TR:

这篇文章大部分内容来自这里，致谢。