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study/Ref-docs/manual Intel386/I386Manual/DIV.HTM
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study/Ref-docs/manual Intel386/I386Manual/DIV.HTM
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<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 DIV</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="DEC.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/DEC.HTM"> DEC Decrement by 1</a><br>
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<b>next:</b><a href="ENTER.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/ENTER.HTM"> ENTER Make Stack Frame for Procedure Parameters</a>
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<p>
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<hr>
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<p>
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<h1>DIV -- Unsigned Divide</h1>
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<pre>
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Opcode Instruction Clocks Description
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F6 /6 DIV AL,r/m8 14/17 Unsigned divide AX by r/m byte
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(AL=Quo, AH=Rem)
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F7 /6 DIV AX,r/m16 22/25 Unsigned divide DX:AX by r/m
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word (AX=Quo, DX=Rem)
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F7 /6 DIV EAX,r/m32 38/41 Unsigned divide EDX:EAX by r/m
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dword (EAX=Quo, EDX=Rem)
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</pre>
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<h2>Operation</h2>
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<pre>
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temp := dividend / divisor;
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IF temp does not fit in quotient
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THEN Interrupt 0;
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ELSE
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quotient := temp;
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remainder := dividend MOD (r/m);
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FI;
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</pre>
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<em>
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<h3>Note</h3>
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Divisions are unsigned. The divisor is given by the r/m operand. The dividend, quotient, and remainder use implicit registers. Refer to the table under "Description" </em>
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<h2>Description</h2>
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DIV performs an unsigned division. The dividend is implicit; only the divisor is given as an operand. The remainder is always less than the divisor. The type of the divisor determines which registers to use as follows:
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<pre>
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Size Dividend Divisor Quotient Remainder
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byte AX r/m8 AL AH
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word DX:AX r/m16 AX DX
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dword EDX:EAX r/m32 EAX EDX
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</pre>
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<h2>Flags Affected</h2>
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OF, SF, ZF, AR, PF, CF are undefined.
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<h2>Protected Mode Exceptions</h2>
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Interrupt 0 if the quotient is too large to fit in the designated register (AL, AX, or EAX), or if the divisor is 0; #GP(0) for an illegal memory operand effective address in the CS, DS, ES, FS, or GS segments; #SS(0) for an illegal address in the SS segment; #PF(fault-code) for a page fault
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<h2>Real Address Mode Exceptions</h2>
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Interrupt 0 if the quotient is too big to fit in the designated register (AL, AX, or EAX), or if the divisor is 0; Interrupt 13 if any part of the operand would lie outside of the effective address space from 0 to 0FFFFH
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<h2>Virtual 8086 Mode Exceptions</h2>
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Same exceptions as in Real Address Mode; #PF(fault-code) for a page fault
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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="DEC.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/DEC.HTM"> DEC Decrement by 1</a><br>
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<b>next:</b><a href="ENTER.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/ENTER.HTM"> ENTER Make Stack Frame for Procedure Parameters</a>
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</body>
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