i386/i386.reference/MOVZX.htm

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   4 <TITLE>80386 Programmer's Reference Manual -- Opcode MOVZX</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="MOVSX.htm"> MOVSX Move with Sign-Extend</A><BR>
  10 <B>next:</B><A HREF="MUL.htm"> MUL Unsigned Multiplication of AL or AX</A>
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  13 <P>
  14 <H1>MOVZX -- Move with Zero-Extend</H1>
  15
  16 <PRE>
  17 Opcode      Instruction        Clocks   Description
  18
  19 0F  B6 /r   MOVZX r16,r/m8     3/6      Move byte to word with zero-extend
  20 0F  B6 /r   MOVZX r32,r/m8     3/6      Move byte to dword, zero-extend
  21 0F  B7 /r   MOVZX r32,r/m16    3/6      Move word to dword, zero-extend
  22 </PRE>
  23
  24 <H2>Operation</H2>
  25
  26 <PRE>
  27 DEST := ZeroExtend(SRC);
  28 </PRE>
  29
  30 <H2>Description</H2>
  31
  32 MOVZX reads the contents of the effective address or register as a byte
  33 or a word, zero extends the value to the operand-size attribute of the
  34 instruction (16 or 32 bits), and stores the result in the destination
  35 register.
  36
  37 <H2>Flags Affected</H2>
  38
  39 None
  40
  41 <H2>Protected Mode Exceptions</H2>
  42
  43 #GP(0) for an illegal memory operand effective address in the CS, DS,
  44 ES, FS, or GS segments; #SS(0) for an illegal address in the SS segment;
  45 #PF(fault-code) for a page fault
  46
  47 <H2>Real Address Mode Exceptions</H2>
  48
  49 Interrupt 13 if any part of the operand would lie outside of the effective
  50 address space from 0 to 0FFFFH
  51
  52 <H2>Virtual 8086 Mode Exceptions</H2>
  53
  54 Same exceptions as in Real Address Mode; #PF(fault-code) for a page
  55 fault
  56
  57
  58 <P>
  59 <HR>
  60 <P>
  61 <B>up:</B> <A HREF="c17.htm">
  62 Chapter 17 -- 80386 Instruction Set</A><BR>
  63 <B>prev:</B><A HREF="MOVSX.htm"> MOVSX Move with Sign-Extend</A><BR>
  64 <B>next:</B><A HREF="MUL.htm"> MUL Unsigned Multiplication of AL or AX</A>
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