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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"><HTML><HEAD><TITLE>80386 Programmer's Reference Manual -- Opcode IDIV</TITLE></HEAD><BODY><B>up:</B> <A HREF="c17.htm">Chapter 17 -- 80386 Instruction Set</A><BR><B>prev:</B><A HREF="HLT.htm"> HLT Halt</A><BR><B>next:</B><A HREF="IMUL.htm"> IMUL Signed Multiply</A><P><HR><P><H1>IDIV -- Signed Divide</H1><PRE>Opcode Instruction Clocks DescriptionF6 /7 IDIV r/m8 19 Signed divide AX by r/m byte (AL=Quo, AH=Rem)F7 /7 IDIV AX,r/m16 27 Signed divide DX:AX by EA word (AX=Quo, DX=Rem)F7 /7 IDIV EAX,r/m32 43 Signed divide EDX:EAX by DWORD byte (EAX=Quo, EDX=Rem)</PRE><H2>Operation</H2><PRE>temp := dividend / divisor;IF temp does not fit in quotientTHEN Interrupt 0;ELSE quotient := temp; remainder := dividend MOD (r/m);FI;</PRE><EM><H3>Notes</H3> Divisions are signed. 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>IDIV performs a signed division. The dividend, quotient, and remainderare implicitly allocated to fixed registers. Only the divisor is given asan explicit r/m operand. The type of the divisor determines which registersto use as follows:<PRE>Size Divisor Quotient Remainder Dividendbyte r/m8 AL AH AXword r/m16 AX DX DX:AXdword r/m32 EAX EDX EDX:EAX</PRE>If the resulting quotient is too large to fit in the destination, or if thedivision is 0, an Interrupt 0 is generated. Nonintegral quotients aretruncated toward 0. The remainder has the same sign as the dividendand the absolute value of the remainder is always less than the absolutevalue of the divisor.<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 or AX), or if the divisor is 0; #GP (0) for an illegal memory operandeffective address in the CS, DS, ES, FS, or GS segments; #SS(0) for anillegal 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 large to fit in the designated register(AL or AX), or if the divisor is 0; Interrupt 13 if any part of the operandwould 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 pagefault<P><HR><P><B>up:</B> <A HREF="c17.htm">Chapter 17 -- 80386 Instruction Set</A><BR><B>prev:</B><A HREF="HLT.htm"> HLT Halt</A><BR><B>next:</B><A HREF="IMUL.htm"> IMUL Signed Multiply</A></BODY>?? 快捷鍵說明
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