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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"><HTML><HEAD><TITLE>80386 Programmer's Reference Manual -- Opcode AAA</TITLE></HEAD><BODY><B>up:</B> <A HREF="c17.htm">Chapter 17 -- 80386 Instruction Set</A><BR><B>prev:</B> <A HREF="s17_02.htm">17.2 Instruction Format</A><BR><B>next:</B><A HREF="AAD.htm"> AAD ASCII Adjust AX before Division</A><P><HR><P><H1>AAA -- ASCII Adjust after Addition</H1><PRE>Opcode Instruction Clocks Description37 AAA 4 ASCII adjust AL after addition</PRE><H2>Operation</H2><PRE>IF ((AL AND 0FH) > 9) OR (AF = 1)THEN AL := (AL + 6) AND 0FH; AH := AH + 1; AF := 1; CF := 1;ELSE CF := 0; AF := 0;FI;</PRE><H2>Description</H2>Execute AAA only following an <A HREF="ADD.htm">ADD</A> instruction that leaves a byte resultin the AL register. The lower nibbles of the operands of the <A HREF="ADD.htm">ADD</A> instructionshould be in the range 0 through 9 (BCD digits). In this case, AAA adjustsAL to contain the correct decimal digit result. If the addition produced adecimal carry, the AH register is incremented, and the carry and auxiliarycarry flags are set to 1. If there was no decimal carry, the carry andauxiliary flags are set to 0 and AH is unchanged. In either case, AL is leftwith its top nibble set to 0. To convert AL to an ASCII result, follow theAAA instruction with <A HREF="OR.htm">OR</A> AL, 30H.<H2>Flags Affected</H2>AF and CF as described above; OF, SF, ZF, and PF are undefined<H2>Protected Mode Exceptions</H2>None<H2>Real Address 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="s17_02.htm">17.2 Instruction Format</A><BR><B>next:</B><A HREF="AAD.htm"> AAD ASCII Adjust AX before Division</A></BODY>⌨️ 快捷键说明
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