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Made C's sizeof operator work with initialized void variables.

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Added regression tests that check cc65's handling of void variables.
This commit is contained in:
Greg King
2017-03-12 12:55:31 -04:00
parent a780df1fe1
commit 750a527100
7 changed files with 147 additions and 62 deletions
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47
doc/cc65.sgml
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@@ -4,7 +4,7 @@
<title>cc65 Users Guide
<author><url url="mailto:uz@cc65.org" name="Ullrich von Bassewitz">,<newline>
<url url="mailto:gregdk@users.sf.net" name="Greg King">
<date>2016-06-11
<date>2017-02-27
<abstract>
cc65 is a C compiler for 6502 targets. It supports several 6502 based home
@@ -687,30 +687,37 @@ This cc65 version has some extensions to the ISO C standard.
string.
<p>
<item> cc65 allows the initialization of <tt/void/ variables. This may be
used to create variable structures that are more compatible with
interfaces written for assembler languages. Here is an example:
<item> cc65 allows the initialization of <tt/void/ variables. This may be
used to create arbitrary structures that are more compatible with
interfaces written for assembler languages. Here is an example:
<tscreen><verb>
void GCmd = { (char)3, (unsigned)0x2000, (unsigned)0x3000 };
</verb></tscreen>
<tscreen><verb>
void GCmd = { (char)3, (unsigned)0x2000, (unsigned)0x3000 };
</verb></tscreen>
This will be translated as follows:
That will be translated as follows:
<tscreen><verb>
_GCmd:
.byte 3
.word $2000
.word $3000
</verb></tscreen>
<tscreen><verb>
_GCmd:
.byte 3
.word $2000
.word $3000
</verb></tscreen>
Since the variable is of type <tt/void/ you may not use it as is.
However, taking the address of the variable results in a <tt/void*/
which may be passed to any function expecting a pointer.
Since the variable is of type <tt/void/, you may not use it as-is.
However, taking the address of the variable results in a <tt/void*/
which may be passed to any function expecting a pointer. Also, the
<tt/sizeof/ operator will give the length of the initializer:
See the <url url="geos.html" name="GEOS library document"> for examples
on how to use this feature.
<p>
<tscreen><verb>
GLen = sizeof GCmd;
</verb></tscreen>
will assign the value 5 to <tt/GLen/.
See the <url url="geos.html" name="GEOS library document"> for examples
on how to use that feature.
<p>
<item> cc65 implements flexible array struct members as defined in the C99 ISO
standard. As an extension, these fields may be initialized. There are