72 lines
3.2 KiB
HTML
72 lines
3.2 KiB
HTML
<html><!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
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<html>
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<head>
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<title>80386 Programmer's Reference Manual -- Opcode MOV Special Registers</title>
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</head>
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<body>
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<b>up:</b> <a href="C17.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/C17.HTM">Chapter 17 -- 80386 Instruction Set</a><br>
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<b>prev:</b><a href="MOV.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/MOV.HTM"> MOV Move Data</a><br>
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<b>next:</b><a href="MOVS.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/MOVS.HTM"> MOVS/MOVSB/MOVSW/MOVSD Move Data from String to String</a>
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<p>
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<hr>
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<p>
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<h1>MOV -- Move to/from Special Registers</h1>
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<pre>
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Opcode Instruction Clocks Description
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0F 20 /r MOV r32,CR0/CR2/CR3 6 Move (control register) to
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(register)
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0F 22 /r MOV CR0/CR2/CR3,r32 10/4/5 Move (register) to (control
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register)
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0F 21 /r MOV r32,DR0 -- 3 22 Move (debug register) to
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(register)
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0F 21 /r MOV r32,DR6/DR7 14 Move (debug register) to
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(register)
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0F 23 /r MOV DR0 -- 3,r32 22 Move (register) to (debug
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register)
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0F 23 /r MOV DR6/DR7,r32 16 Move (register) to (debug
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register)
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0F 24 /r MOV r32,TR6/TR7 12 Move (test register) to
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(register)
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0F 26 /r MOV TR6/TR7,r32 12 Move (register) to (test
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register)
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</pre>
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<h2>Operation</h2>
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<pre>
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DEST := SRC;
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</pre>
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<h2>Description</h2>
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The above forms of MOV store or load the following special registers in or from a general purpose register:
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<ul>
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<li>Control registers CR0, CR2, and CR3
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<li>Debug Registers DR0, DR1, DR2, DR3, DR6, and DR7
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<li>Test Registers TR6 and TR7
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</ul>
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32-bit operands are always used with these instructions, regardless of the operand-size attribute.
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<h2>Flags Affected</h2>
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OF, SF, ZF, AF, PF, and CF are undefined
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<h2>Protected Mode Exceptions</h2>
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#GP(0) if the current privilege level is not 0
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<h2>Real Address Mode Exceptions</h2>
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None
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<h2>Virtual 8086 Mode Exceptions</h2>
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#GP(0) if instruction execution is attempted
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<h2>Notes</h2>
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The instructions must be executed at privilege level 0 or in real-address mode; otherwise, a protection exception will be raised.
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<p>The reg field within the ModRM byte specifies which of the special registers in each category is involved. The two bits in the field are always 11. The r/m field specifies the general register involved.
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<p>
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<hr>
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<p><b>up:</b> <a href="C17.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/C17.HTM">Chapter 17 -- 80386 Instruction Set</a><br>
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<b>prev:</b><a href="MOV.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/MOV.HTM"> MOV Move Data</a><br>
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<b>next:</b><a href="MOVS.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/MOVS.HTM"> MOVS/MOVSB/MOVSW/MOVSD Move Data from String to String</a>
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</body>
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