i386/i386.reference/OUT.htm

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   4 <TITLE>80386 Programmer's Reference Manual -- Opcode OUT</TITLE>
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   8 Chapter 17 -- 80386 Instruction Set</A><BR>
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  13 <P>
  14 <H1>OUT -- Output to Port</H1>
  15
  16 <PRE>
  17 Opcode    Instruction     Clocks          Description
  18
  19 E6  ib    OUT imm8,AL     10,pm=4*/24**   Output byte AL to immediate port
  20                                           number
  21 E7  ib    OUT imm8,AX     10,pm=4*/24**   Output word AL to immediate port
  22                                           number
  23 E7  ib    OUT imm8,EAX    10,pm=4*/24**   Output dword AL to immediate
  24                                           port number
  25 EE        OUT DX,AL       11,pm=5*/25**   Output byte AL to port number in
  26 DX
  27 EF        OUT DX,AX       11,pm=5*/25**   Output word AL to port number in
  28 DX
  29 EF        OUT DX,EAX      11,pm=5*/25**   Output dword AL to port number
  30                                           in DX
  31 </PRE>
  32
  33
  34 <EM>
  35 <H3>Notes</H3>
  36 <PRE>
  37    *If CPL <= IOPL
  38   **If CPL > IOPL or if in virtual 8086 mode
  39 </PRE>
  40 </EM>
  41
  42 <H2>Operation</H2>
  43
  44 <PRE>
  45 IF (PE = 1) AND ((VM = 1) OR (CPL > IOPL))
  46 THEN (* Virtual 8086 mode, or protected mode with CPL > IOPL *)
  47    IF NOT I-O-Permission (DEST, width(DEST))
  48    THEN #GP(0);
  49    FI;
  50 FI;
  51 [DEST] := SRC; (* I/O address space used *)
  52 </PRE>
  53
  54 <H2>Description</H2>
  55
  56 OUT transfers a data byte or data word from the register (AL, AX, or
  57 EAX) given as the second operand to the output port numbered by the
  58 first operand. Output to any port from 0 to 65535 is performed by placing
  59 the port number in the DX register and then using an OUT instruction
  60 with DX as the first operand. If the instruction contains an eight-bit port
  61 ID, that value is zero-extended to 16 bits.
  62
  63 <H2>Flags Affected</H2>
  64
  65 None
  66
  67 <H2>Protected Mode Exceptions</H2>
  68
  69 #GP(0) if the current privilege level is higher (has less privilege) than
  70 IOPL and any of the corresponding I/O permission bits in TSS equals 1
  71
  72 <H2>Real Address Mode Exceptions</H2>
  73
  74 None
  75
  76 <H2>Virtual 8086 Mode Exceptions</H2>
  77
  78 #GP(0) fault if any of the corresponding I/O permission bits in TSS
  79 equals 1
  80
  81
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  84 <P>
  85 <B>up:</B> <A HREF="c17.htm">
  86 Chapter 17 -- 80386 Instruction Set</A><BR>
  87 <B>prev:</B><A HREF="OR.htm"> OR Logical Inclusive OR</A><BR>
  88 <B>next:</B><A HREF="OUTS.htm"> OUTS/OUTSB/OUTSW/OUTSD Output String to Port</A>
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