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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"><HTML><HEAD><TITLE>80386 Programmer's Reference Manual -- Opcode DAA</TITLE></HEAD><BODY><B>up:</B> <A HREF="c17.htm">Chapter 17 -- 80386 Instruction Set</A><BR><B>prev:</B><A HREF="CWD.htm"> CWD/CDQ Convert Word to Doubleword/Convert Doubleword to Quadword</A><BR><B>next:</B><A HREF="DAS.htm"> DAS Decimal Adjust AL after Subtraction</A><P><HR><P><H1>DAA -- Decimal Adjust AL after Addition</H1><PRE>Opcode Instruction Clocks Description27 DAA 4 Decimal adjust AL after addition</PRE><H2>Operation</H2><PRE>IF ((AL AND 0FH) > 9) OR (AF = 1)THEN AL := AL + 6; AF := 1;ELSE AF := 0;FI;IF (AL > 9FH) OR (CF = 1)THEN AL := AL + 60H; CF := 1;ELSE CF := 0;FI;</PRE><H2>Description</H2>Execute DAA only after executing an <A HREF="ADD.htm">ADD</A> instruction that leaves atwo-BCD-digit byte result in the AL register. The <A HREF="ADD.htm">ADD</A> operands shouldconsist of two packed BCD digits. The DAA instruction adjusts AL tocontain the correct two-digit packed decimal result.<H2>Flags Affected</H2>AF and CF as described above; SF, ZF, PF, and CF as described in<A HREF="appc.htm">Appendix C</A>.<H2>Protected Mode Exceptions</H2>None<H2>Real Address Mode Exceptions</H2>None<H2>Virtual 8086 Mode Exceptions</H2>None<P><HR><P><B>up:</B> <A HREF="c17.htm">Chapter 17 -- 80386 Instruction Set</A><BR><B>prev:</B><A HREF="CWD.htm"> CWD/CDQ Convert Word to Doubleword/Convert Doubleword to Quadword</A><BR><B>next:</B><A HREF="DAS.htm"> DAS Decimal Adjust AL after Subtraction</A></BODY>⌨️ 快捷键说明
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