📄 nestdefs.htm

📁 一份51的编译程序,dos版本的. 英文名字MCS-51 Microcontroller Family Macro Assembler
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<STRONG><U>III.11.8 Nested Macro Definitions</U></STRONG>
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<P>
A macro body may also contain further macro definitions. However, these
nested macro definitions aren't valid until the enclosing macro has been
expanded! That means, the enclosing macro must have been called, before
the nested macros can be called.
</P>

<P>
<BR>
<STRONG>Example 1:</STRONG>
<BLOCKQUOTE>
A macro, which can be used to define macros with arbitrary
names, may look as follows:
<PRE>
        DEFINE MACRO MACNAME
        MACNAME MACRO
        DB 'I am the macro &amp;MACNAME.'
        ENDM
        ENDM
</PRE>
In order not to overload the example with &quot;knowhow&quot;, the nested
macro only introduces itself kindly with a suitable character string in ROM.
The call
<PRE>
        DEFINE Obiwan
</PRE>
would define the macro
<PRE>
        Obiwan MACRO
        DB 'I am the macro Obiwan.'
        ENDM
</PRE>
and the call
<PRE>
        DEFINE Skywalker
</PRE>
would define the following macro:
<PRE>
        Skywalker MACRO
        DB 'I am the macro Skywalker.'
        ENDM
</PRE>
</BLOCKQUOTE>
</P>

<P>
<BR>
<STRONG>Example 2:</STRONG>
<BLOCKQUOTE>
A macro is to insert a variable number of NOPs into the
program. For this, a macro with a nested REPT block seems
to be best-suited:
<PRE>
        REPEAT MACRO NOPS
        REPT NOPS
        NOP
        ENDM
        ENDM
</PRE>
The macro call
<PRE>
        REPEAT 4
</PRE>
results in something like that:
<PRE>
        Line  I  Addr  Code            Source

           9+ 1        N      0004     REPT 4
          10+ 1                        NOP
          11+ 1                        ENDM
          12+ 2  0000  00              NOP
          13+ 2  0001  00              NOP
          14+ 2  0002  00              NOP
          15+ 2  0003  00              NOP
</PRE>
</BLOCKQUOTE>
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