hw/i386.reference/OR.htm

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   4 <TITLE>80386 Programmer's Reference Manual -- Opcode OR</TITLE>
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   7 <B>up:</B> <A HREF="c17.htm">
   8 Chapter 17 -- 80386 Instruction Set</A><BR>
   9 <B>prev:</B><A HREF="NOT.htm"> NOT One's Complement Negation</A><BR>
  10 <B>next:</B><A HREF="OUT.htm"> OUT Output to Port</A>
  11 <P>
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  13 <P>
  14 <H1>OR -- Logical Inclusive OR</H1>
  15
  16 <PRE>
  17 Opcode       Instruction       Clocks    Description
  18
  19 0C  ib       OR AL,imm8        2         OR immediate byte to AL
  20 0D  iw       OR AX,imm16       2         OR immediate word to AX
  21 0D  id       OR EAX,imm32      2         OR immediate dword to EAX
  22 80  /1 ib    OR r/m8,imm8      2/7       OR immediate byte to r/m byte
  23 81  /1 iw    OR r/m16,imm16    2/7       OR immediate word to r/m word
  24 81  /1 id    OR r/m32,imm32    2/7       OR immediate dword to r/m dword
  25 83  /1 ib    OR r/m16,imm8     2/7       OR sign-extended immediate byte
  26                                          with r/m word
  27 83  /1 ib    OR r/m32,imm8     2/7       OR sign-extended immediate byte
  28                                          with r/m dword
  29 08  /r       OR r/m8,r8        2/6       OR byte register to r/m byte
  30 09  /r       OR r/m16,r16      2/6       OR word register to r/m word
  31 09  /r       OR r/m32,r32      2/6       OR dword register to r/m dword
  32 0A  /r       OR r8,r/m8        2/7       OR byte register to r/m byte
  33 0B  /r       OR r16,r/m16      2/7       OR word register to r/m word
  34 0B  /r       OR r32,r/m32      2/7       OR dword register to r/m dword
  35 </PRE>
  36
  37
  38 <H2>Operation</H2>
  39
  40 <PRE>
  41 DEST := DEST OR SRC;
  42 CF := 0;
  43 OF := 0
  44 </PRE>
  45
  46 <H2>Description</H2>
  47
  48 OR computes the inclusive OR of its two operands and places the result
  49 in the first operand. Each bit of the result is 0 if both corresponding
  50 bits of the operands are 0; otherwise, each bit is 1.
  51
  52 <H2>Flags Affected</H2>
  53
  54 OF := 0, CF := 0; SF, ZF, and PF as described in <A HREF="appc.htm">Appendix C</A>; AF is
  55 undefined
  56
  57 <H2>Protected Mode Exceptions</H2>
  58
  59 #GP(0) if the result is in a nonwritable segment; #GP(0) for an illegal
  60 memory operand effective address in the CS, DS, ES, FS, or GS
  61 segments; #SS(0) for an illegal address in the SS segment; #PF(fault-code)
  62 for a page fault
  63
  64 <H2>Real Address Mode Exceptions</H2>
  65
  66 Interrupt 13 if any part of the operand would lie outside of the effective
  67 address space from 0 to 0FFFFH
  68
  69 <H2>Virtual 8086 Mode Exceptions</H2>
  70
  71 Same exceptions as in real-address mode; #PF(fault-code) for a page
  72 fault
  73
  74
  75 <P>
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  78 <B>up:</B> <A HREF="c17.htm">
  79 Chapter 17 -- 80386 Instruction Set</A><BR>
  80 <B>prev:</B><A HREF="NOT.htm"> NOT One's Complement Negation</A><BR>
  81 <B>next:</B><A HREF="OUT.htm"> OUT Output to Port</A>
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