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Some documentation fixes. Errors reported by Michael Bazzinotti

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<mbazzinotti@gmail.com>.


git-svn-id: svn://svn.cc65.org/cc65/trunk@5813 b7a2c559-68d2-44c3-8de9-860c34a00d81
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uz 2012-09-02 20:09:39 +00:00
parent 0e183cc8e9
commit 1ddd1288c5
1 changed files with 27 additions and 33 deletions
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60
doc/ca65.sgml
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@ -2892,7 +2892,7 @@ Here's a list of all control commands and a description, what they do:
This command is often used to check if a macro parameter was given. Since an
empty macro parameter will evaluate to nothing, the condition will evaluate
to FALSE if an empty parameter was given.
to TRUE if an empty parameter was given.
Example:
@ -4084,41 +4084,35 @@ written more efficiently, like this:
.endmacro
</verb></tscreen>
But imagine what happens, if you use this macro twice? Since the label
"Skip" has the same name both times, you get a "duplicate symbol" error.
Without a way to circumvent this problem, macros are not as useful, as
they could be. One solution is, to start a new lexical block inside the
macro:
<tscreen><verb>
.macro inc16 addr
.proc
inc addr
bne Skip
inc addr+1
Skip:
.endproc
.endmacro
</verb></tscreen>
Now the label is local to the block and not visible outside. However,
sometimes you want a label inside the macro to be visible outside. To make
that possible, there's a new command that's only usable inside a macro
definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
or more symbols as local to the macro expansion. The names of local variables
are replaced by a unique name in each separate macro expansion. So we could
also solve the problem above by using <tt/.LOCAL/:
But imagine what happens, if you use this macro twice? Since the label "Skip"
has the same name both times, you get a "duplicate symbol" error. Without a
way to circumvent this problem, macros are not as useful, as they could be.
One possible solution is the command <tt><ref id=".LOCAL" name=".LOCAL"></tt>.
It declares one or more symbols as local to the macro expansion. The names of
local variables are replaced by a unique name in each separate macro
expansion. So we can solve the problem above by using <tt/.LOCAL/:
<tscreen><verb>
.macro inc16 addr
.local Skip ; Make Skip a local symbol
clc
lda addr
adc #$01
sta addr
bcc Skip
inc addr+1
Skip: ; Not visible outside
inc addr
bne Skip
inc addr+1
Skip: ; Not visible outside
.endmacro
</verb></tscreen>
Another solution is of course to start a new lexical block inside the macro
that hides any labels:
<tscreen><verb>
.macro inc16 addr
.proc
inc addr
bne Skip
inc addr+1
Skip:
.endproc
.endmacro
</verb></tscreen>
@ -4199,7 +4193,7 @@ detect the end of one parameter, only the first token is used. If you
don't like that, use classic macros instead:
<tscreen><verb>
.macro message
.macro DEBUG message
.out message
.endmacro
</verb></tscreen>