in out怎么用？？急！！！！！！（汇编中，386）

[cuick2000]

用到哪些寄存器？？我手头没书，可怜！！！！

[awinder]

IN - Input from Port
E4 ib IN AL, imm8 Input byte from imm8 I/O port address into AL
E5 ib IN AX, imm8 Input byte from imm8 I/O port address into AX
E5 ib IN EAX, imm8 Input byte from imm8 I/O port address into EAX
EC IN AL,DX Input byte from I/O port in DX into AL
ED IN AX,DX Input word from I/O port in DX into AX
ED IN EAX,DX Input doubleword from I/O port in DX into EAX

Description
Copies the value from the I/O port specified with the second operand (source operand) to the destination operand (first operand). The source operand can be a byte-immediate or the DX register; the destination operand can be register AL, AX, or EAX, depending on the size of the port being accessed (8, 16, or 32 bits, respectively). Using the DX register as a source operand allows I/O port addresses from 0 to 65,535 to be accessed; using a byte immediate allows I/O port addresses 0 to 255 to be accessed.

When accessing an 8-bit I/O port, the opcode determines the port size; when accessing a 16- and 32-bit I/O port, the operand-size attribute determines the port size.

At the machine code level, I/O instructions are shorter when accessing 8-bit I/O ports. Here, the upper eight bits of the port address will be 0.

This instruction is only useful for accessing I/O ports located in the processor's I/O address space. See Chapter 9, Input/Output, in the Intel Architecture Software Developer's Manual, Vo l u me 1 , for more information on accessing I/O ports in the I/O address space.

Operands Bytes Clocks
al, imm8 2 7 NP
ax, imm8 2 7 NP
eax, imm8 2 7 NP
al, dx 1 7 NP
ax, dx 1 7 NP
eax, dx 1 7 NP

Protected mode
acc, imm 2 4/21/19 NP
acc, dx 1 4/21/19 NP

cycles for: CPL <= IOPL / CPL > IOPL / V86

Flags
None.


OUT - Output to Port
E6 ib OUT imm8, AL Output byte in AL to I/O port address imm8
E7 ib OUT imm8, AX Output word in AX to I/O port address imm8
E7 ib OUT imm8, EAX Output doubleword in EAX to I/O port address imm8
EE OUT DX, AL Output byte in AL to I/O port address in DX
EF OUT DX, AX Output word in AX to I/O port address in DX
EF OUT DX, EAX Output doubleword in EAX to I/O port address in DX

Description
Copies the value from the second operand (source operand) to the I/O port specified with the destination operand (first operand). The source operand can be register AL, AX, or EAX, depending on the size of the port being accessed (8, 16, or 32 bits, respectively); the destination operand can be a byte-immediate or the DX register. Using a byte immediate allows I/O port addresses 0 to 255 to be accessed; using the DX register as a source operand allows I/O ports from 0 to 65,535 to be accessed.

The size of the I/O port being accessed is determined by the opcode for an 8-bit I/O port or by the operand-size attribute of the instruction for a 16- or 32-bit I/O port.

At the machine code level, I/O instructions are shorter when accessing 8-bit I/O ports. Here, the upper eight bits of the port address will be 0.

This instruction is only useful for accessing I/O ports located in the processor's I/O address space. See Chapter 9, Input/Output, in the Intel Architecture Software Developer's Manual, Vo l u me 1 , for more information on accessing I/O ports in the I/O address space.

Operands Bytes Clocks
imm8, al 2 12 NP
imm8, ax 2 12 NP
imm8, eax 2 12 NP
dx, al 1 12 NP
dx, ax 1 12 NP
dx, eax 1 12 NP

Protected Mode
imm8, acc 2 9/26/24 NP
dx, acc 1 9/26/24 NP

cycles for: CPL <= IOPL / CPL > IOPL / V86

Flags
None.

[CodeDemon]

up!!!

[wowocock]

简单的说只用到AL（8），AX（16），EAX（32），用于存放数据，DX指定端口号。