72 lines
3.1 KiB
HTML
72 lines
3.1 KiB
HTML
<html><!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
|
|
<html>
|
|
|
|
<head>
|
|
<title>80386 Programmer's Reference Manual -- Opcode DIV</title>
|
|
</head>
|
|
|
|
<body>
|
|
<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>
|
|
<b>prev:</b><a href="DEC.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/DEC.HTM"> DEC Decrement by 1</a><br>
|
|
<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>
|
|
<p>
|
|
<hr>
|
|
<p>
|
|
<h1>DIV -- Unsigned Divide</h1>
|
|
<pre>
|
|
|
|
|
|
|
|
Opcode Instruction Clocks Description
|
|
|
|
F6 /6 DIV AL,r/m8 14/17 Unsigned divide AX by r/m byte
|
|
(AL=Quo, AH=Rem)
|
|
F7 /6 DIV AX,r/m16 22/25 Unsigned divide DX:AX by r/m
|
|
word (AX=Quo, DX=Rem)
|
|
F7 /6 DIV EAX,r/m32 38/41 Unsigned divide EDX:EAX by r/m
|
|
dword (EAX=Quo, EDX=Rem)
|
|
</pre>
|
|
<h2>Operation</h2>
|
|
<pre>
|
|
|
|
|
|
|
|
temp := dividend / divisor;
|
|
IF temp does not fit in quotient
|
|
THEN Interrupt 0;
|
|
ELSE
|
|
quotient := temp;
|
|
remainder := dividend MOD (r/m);
|
|
FI;
|
|
</pre>
|
|
<em>
|
|
<h3>Note</h3>
|
|
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>
|
|
<h2>Description</h2>
|
|
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:
|
|
<pre>
|
|
|
|
|
|
|
|
|
|
Size Dividend Divisor Quotient Remainder
|
|
byte AX r/m8 AL AH
|
|
word DX:AX r/m16 AX DX
|
|
dword EDX:EAX r/m32 EAX EDX
|
|
</pre>
|
|
<h2>Flags Affected</h2>
|
|
OF, SF, ZF, AR, PF, CF are undefined.
|
|
<h2>Protected Mode Exceptions</h2>
|
|
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
|
|
<h2>Real Address Mode Exceptions</h2>
|
|
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
|
|
<h2>Virtual 8086 Mode Exceptions</h2>
|
|
Same exceptions as in Real Address Mode; #PF(fault-code) for a page fault
|
|
<p>
|
|
<hr>
|
|
<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>
|
|
<b>prev:</b><a href="DEC.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/DEC.HTM"> DEC Decrement by 1</a><br>
|
|
<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>
|
|
</body>
|
|
|