exitm.htm

来自「Free 8051 asm compiler for linux new ho」· HTM 代码 · 共 109 行

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><!-- Premature End of a Macro Expansion --><HTML><HEAD><TITLE>Premature End of a Macro Expansion</TITLE></HEAD><BODY BACKGROUND="spiral.gif" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#990099" ALINK="#FF0000"><TABLE WIDTH="98%"><TR><TD WIDTH=60 VALIGN=BOTTOM NOWRAP><IMG SRC="transp.gif" ALT="" WIDTH=60 HEIGHT=20></TD><TD><!-- Ab hier Seitentext: --><BIG><BR><P><STRONG><U>III.11.6 Premature End of a Macro Expansion</U></STRONG></P><P>Sometimes it is useful, if a macro expansion can be terminated, beforethe end of the macro body is reached. This can be forced with the EXITM(exit macro) instruction. However, this makes sense in conjunction withconditional assembly only.</P><P><BR><STRONG>Example:</STRONG><BLOCKQUOTE><PRE>        FLEXIBLE MACRO QUANTITY        DB 'Text'        IF QUANTITY LE 255        EXITM        ENDIF        DW QUANTITY        ENDM</PRE>The macro FLEXIBLE always has to insert the string 'Text'into the CODE space. After that, it should insert a 16-bitconstant only, if the numerical value of the parameterQUANTITY is greater than 255.<BR>Otherwise the macro expansion should be terminated withEXITM before. If the macro is called as follows,<PRE>        FLEXIBLE 42</PRE>it will be expanded to<PRE>        DB 'Text'</PRE>in list mode $GENONLY/$CONDONLY.<BR>However, if it is called like this,<PRE>        FLEXIBLE 4711</PRE>it will be expanded to:<PRE>        DB 'Text'        DW 4711</PRE></BLOCKQUOTE></P><P>When a macro expansion is terminated with EXITM, all IFxx constructions thathave been opened within the macro body so far, are closed.<BR>Of course macro bodies may also contain control statements. If an includefile is inserted into a macro body with a $INCLUDE control, and this includefile, or a nested include file, contains an EXITM instruction, all includefile levels up to the next macro level are closed at this point, and theexpansion of that macro is terminated immediately.</P></BIG><!-- Seitentext Ende --><P><BR><BR><CENTER><TABLE WIDTH="70%"><TR><TH><A HREF="contents.htm"><IMG SRC="home.gif" ALT="[contents]" BORDER=0 WIDTH=32 HEIGHT=32></A></TH>    <TH><A HREF="macros.htm"><IMG SRC="up.gif" ALT="[up]" BORDER=0 WIDTH=32 HEIGHT=32></A></TH>    <TH><A HREF="operator.htm"><IMG SRC="back.gif" ALT="[back]" BORDER=0 WIDTH=32 HEIGHT=32></A></TH>    <TH><A HREF="nestcall.htm"><IMG SRC="next.gif" ALT="[next]" BORDER=0 WIDTH=32 HEIGHT=32></A></TH></TR></TABLE></CENTER></P></TD></TR></TABLE></BODY></HTML>

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本页面展示了「Free 8051 asm compiler for linux new host platforms: Win32 and Linux macro processing dramatica」中的 exitm.htm 源码文件，采用 HTM 编程语言编写，共 109 行代码。您可以在线阅读完整代码内容，也可以返回资源详情页下载完整源码包进行本地学习和开发。

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