모두의 코드
IN (Intel x86/64 assembly instruction)
IN
Input from Port
참고 사항
아래 표를 해석하는 방법은 x86-64 명령어 레퍼런스 읽는 법 글을 참조하시기 바랍니다.
Opcode | Instruction | Op/ | 64-Bit | Compat/ | Description |
|---|---|---|---|---|---|
E4 ib | IN AL imm8 | I | Valid | Valid | Input byte from imm8 I/O port address into AL. |
E5 ib | IN AX imm8 | I | Valid | Valid | Input word from imm8 I/O port address into AX. |
E5 ib | IN EAX imm8 | I | Valid | Valid | Input dword from imm8 I/O port address into EAX. |
EC | IN AL DX | NP | Valid | Valid | Input byte from I/O port in DX into AL. |
ED | IN AX DX | NP | Valid | Valid | Input word from I/O port in DX into AX. |
ED | IN EAX DX | NP | Valid | Valid | Input doubleword from I/O port in DX into EAX. |
Instruction Operand Encoding
Op/En | Operand 1 | Operand 2 | Operand 3 | Operand 4 |
|---|---|---|---|---|
I | imm8 | NA | NA | NA |
NP | NA | NA | NA | NA |
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 imme-diate 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 18, "Input/Output," in the Intel(R) 64 and IA-32 Architectures Software Developer's Manual, Volume 1, for more infor-mation on accessing I/O ports in the I/O address space.
This instruction's operation is the same in non-64-bit modes and 64-bit mode.
Operation
IF ((PE = 1) and ((CPL > IOPL) or (VM = 1)))
THEN (* Protected mode with CPL > IOPL or virtual-8086 mode *)
IF (Any I/O Permission Bit for I/O port being accessed = 1)
THEN (* I/O operation is not allowed *)
#GP(0);
ELSE ( * I/O operation is allowed *)
DEST <- SRC; (* Read from selected I/O port *)
FI;
ELSE (Real Mode or Protected Mode with CPL <= IOPL *)
DEST <- SRC; (* Read from selected I/O port *)
FI;
Flags Affected
None
Protected Mode Exceptions
#GP(0)
If the CPL is greater than (has less privilege) the I/O privilege level (IOPL) and any of the corresponding I/O permission bits in TSS for the I/O port being accessed is 1.
#UD
If the LOCK prefix is used.
Real-Address Mode Exceptions
#UD
If the LOCK prefix is used.
Virtual-8086 Mode Exceptions
#GP(0)
If any of the I/O permission bits in the TSS for the I/O port being accessed is 1.
#PF(fault-code)
If a page fault occurs.
#UD
If the LOCK prefix is used.
Compatibility Mode Exceptions
Same exceptions as in protected mode.
64-Bit Mode Exceptions
#GP(0)
If the CPL is greater than (has less privilege) the I/O privilege level (IOPL) and any of the corresponding I/O permission bits in TSS for the I/O port being accessed is 1.
#UD
If the LOCK prefix is used.
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