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.TAG, structs and unions

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git-svn-id: svn://svn.cc65.org/cc65/trunk@2703 b7a2c559-68d2-44c3-8de9-860c34a00d81
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cuz 2003-12-02 22:53:40 +00:00
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@ -1175,6 +1175,12 @@ Here's a list of all control commands and a description, what they do:
End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
<sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
Ends a struct definition. See the section named <ref id="structs"
name="Structs and unions">.
<sect1><tt>.ENUM</tt><label id=".ENUM"><p>
Start an enumeration. This directive is very similar to the C <tt/enum/
@ -2389,6 +2395,12 @@ Here's a list of all control commands and a description, what they do:
</verb></tscreen>
<sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
Starts a struct definition. See the section named <ref id="structs"
name="Structs and unions">.
<sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
Enable the SunPlus instructions set. This command will not work in the
@ -2400,6 +2412,23 @@ Here's a list of all control commands and a description, what they do:
<tt><ref id=".P816" name=".P816"></tt>
<sect1><tt>.TAG</tt><label id=".TAG"><p>
Allocate space for a struct or union.
Example:
<tscreen><verb>
.struct Point
xcoord .word
ycoord .word
.endstruct
.bss
.tag Point ; Allocate 4 bytes
</verb></tscreen>
<sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
Builtin function. The function accepts a token list in braces. The
@ -3032,6 +3061,63 @@ CPUs (the latter two are upwards compatible to the 65SC02).
<sect>Structs and unions<label id="structs"><p>
Structs and unions are special forms of <ref id="scopes" name="scopes">. They
are to some degree comparable to their C counterparts. Both have a list of
members. Each member allocates storage and may optionally have a name, which,
in case of a struct, is the offset from the beginning and, in case of a union
is always zero.
Here is an example for a very simple struct with two members and a total size
of 4 bytes:
<tscreen><verb>
.struct Point
xcoord .word
ycoord .word
.endstruct
</verb></tscreen>
A union shares the total space between all its members, its size is the same
as that of the largest member.
A struct or union must not necessarily have a name. If it is anonymous, no
local scope is opened, the identifiers used to name the members are placed
into the current scope instead.
A struct may contain unnamed members and definitions of local structs. The
storage allocators may contain a multiplier, as in the example below:
<tscreen><verb>
.struct Circle
.struct Point
.word 2 ; Allocate two words
.endstruct
Radius .word
.endstruct
</verb></tscreen>
Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to embedd
already defined structs or unions in structs:
<tscreen><verb>
.struct Point
xcoord .word
ycoord .word
.endstruct
.struct Circle
Origin .tag Point
Radius .word
.endstruct
</verb></tscreen>
Space for a struct or union may be allocated using the <ref id=".TAG"
name=".TAG"> directive.
<sect>Module constructors/destructors<label id="condes"><p>
<em>Note:</em> This section applies mostly to C programs, so the explanation