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Document the new ubiquitous_idents feature
git-svn-id: svn://svn.cc65.org/cc65/trunk@2982 b7a2c559-68d2-44c3-8de9-860c34a00d81
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doc/ca65.sgml
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doc/ca65.sgml
@ -909,7 +909,58 @@ if you want to access the "other" symbol <tt/bar/, you would have to write:
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</verb></tscreen>
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<sect>Address sizes<label id="address-sizes"><p>
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<sect>Address sizes and memory models<label id="address-sizes"><p>
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<sect1>Address sizes<p>
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ca65 assigns each segment and each symbol an address size. This is true, even
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if the symbol is not used as an address. You may also think of a value range
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of the symbol instead of an address size.
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Possible address sizes are:
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<itemize>
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<item>Zeropage or direct (8 bits)
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<item>Absolute (16 bits)
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<item>Far (24 bits)
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<item>Long (32 bits)
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<itemize>
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Since the assembler uses default address sizes for the segments and symbols,
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it is usually not necessary to override the default behaviour. In cases, where
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it is necessary, the following keywords may be used to specify address sizes:
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<itemize>
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<item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
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<item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
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<item>FAR for far addressing (24 bits).
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<item>LONG or DWORD for long addressing (32 bits).
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<itemize>
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<sect1>Address sizes of segments<p>
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The assembler assigns an address size to each segment. Since the
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representation of a label within this segment is "segment start + offset",
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labels will inherit the address size of the segment they are declared in.
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The address size of a segment may be changed, by using an optional address
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size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
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an explanation on how this is done.
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<sect1>Address sizes of symbols<p>
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<sect1>Memory models<p>
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The default address size of a segment depends on the memory model used. Since
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labels inherit the address size from the segment they are declared in,
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changing the memory model is an easy way to change the address size of many
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symbols at once.
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@ -2025,27 +2076,6 @@ Here's a list of all control commands and a description, what they do:
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<descrip>
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<tag><tt>dollar_is_pc</tt></tag>
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The dollar sign may be used as an alias for the star (`*'), which
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gives the value of the current PC in expressions.
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Note: Assignment to the pseudo variable is not allowed.
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<tag><tt>labels_without_colons</tt></tag>
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Allow labels without a trailing colon. These labels are only accepted,
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if they start at the beginning of a line (no leading white space).
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<tag><tt>loose_string_term</tt></tag>
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Accept single quotes as well as double quotes as terminators for string
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constants.
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<tag><tt>loose_char_term</tt></tag>
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Accept single quotes as well as double quotes as terminators for char
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constants.
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<tag><tt>at_in_identifiers</tt></tag>
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Accept the at character (`@') as a valid character in identifiers. The
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@ -2058,6 +2088,17 @@ Here's a list of all control commands and a description, what they do:
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at character is not allowed to start an identifier, even with this
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feature enabled.
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<tag><tt>dollar_is_pc</tt></tag>
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The dollar sign may be used as an alias for the star (`*'), which
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gives the value of the current PC in expressions.
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Note: Assignment to the pseudo variable is not allowed.
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<tag><tt>labels_without_colons</tt></tag>
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Allow labels without a trailing colon. These labels are only accepted,
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if they start at the beginning of a line (no leading white space).
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<tag><tt>leading_dot_in_identifiers</tt></tag>
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Accept the dot (`.') as the first character of an identifier. This may be
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@ -2067,13 +2108,15 @@ Here's a list of all control commands and a description, what they do:
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overridden. When using this feature, you may also get into trouble if
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later versions of the assembler define new keywords starting with a dot.
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<tag><tt>pc_assignment</tt></tag>
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<tag><tt>loose_char_term</tt></tag>
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Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
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is enabled). Such an assignment is handled identical to the <tt><ref
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id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
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removing the lines with the assignments may also be an option when porting
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code written for older assemblers).
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Accept single quotes as well as double quotes as terminators for char
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constants.
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<tag><tt>loose_string_term</tt></tag>
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Accept single quotes as well as double quotes as terminators for string
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constants.
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<tag><tt>missing_char_term</tt></tag>
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@ -2085,6 +2128,21 @@ Here's a list of all control commands and a description, what they do:
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<bf/Note:/ This does not work in conjunction with <tt/.FEATURE
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loose_string_term/, since in this case the input would be ambigous.
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<tag><tt>pc_assignment</tt></tag>
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Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
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is enabled). Such an assignment is handled identical to the <tt><ref
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id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
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removing the lines with the assignments may also be an option when porting
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code written for older assemblers).
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<tag><tt>ubiquitous_idents</tt></tag>
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Allow the use of instructions names as names for macros and symbols. This
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makes it possible to "overload" instructions by defining a macro with the
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same name. This does also make it possible to introduce hard to find errors
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in your code, so be careful!
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</descrip>
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It is also possible to specify features on the command line using the
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@ -2823,33 +2881,35 @@ Here's a list of all control commands and a description, what they do:
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(and up to 65534 per executable). There are shortcut commands for
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the most common segments ("CODE", "DATA" and "BSS").
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The command is followed by a string containing the segment name (there
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are some constraints for the name - as a rule of thumb use only those
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segment names that would also be valid identifiers). There may also be
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an optional attribute separated by a comma. Valid attributes are
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"<tt/zeropage/" and "<tt/absolute/".
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The command is followed by a string containing the segment name (there are
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some constraints for the name - as a rule of thumb use only those segment
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names that would also be valid identifiers). There may also be an optional
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address size separated by a colon. See the section covering <tt/<ref
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id="address-sizes" name="address sizes">/ for more information.
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When specifying a segment for the first time, "absolute" is the
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default. For all other uses, the attribute specified the first time
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is the default.
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The default address size for a segment depends on the memory model specified
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on the command line. The default is "absolute", which means that you don't
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have to use an address size modifier in most cases.
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"absolute" means that this is a segment with absolute addressing. That
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is, the segment will reside somewhere in core memory outside the zero
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page. "zeropage" means the opposite: The segment will be placed in the
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zero page and direct (short) addressing is possible for data in this
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segment.
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"absolute" means that the is a segment with 16 bit (absolute) addressing.
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That is, the segment will reside somewhere in core memory outside the zero
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page. "zeropage" (8 bit) means that the segment will be placed in the zero
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page and direct (short) addressing is possible for data in this segment.
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Beware: Only labels in a segment with the zeropage attribute are marked
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as reachable by short addressing. The `*' (PC counter) operator will
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work as in other segments and will create absolute variable values.
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Example:
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Please note that a segment cannot have two different address sizes. A
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segment specified as zeropage cannot be declared as being absolute later.
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Examples:
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<tscreen><verb>
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.segment "ROM2" ; Switch to ROM2 segment
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.segment "ZP2", zeropage ; New direct segment
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.segment "ZP2" ; Ok, will use last attribute
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.segment "ZP2", absolute ; Error, redecl mismatch
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.segment "ZP2": zeropage ; New direct segment
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.segment "ZP2" ; Ok, will use last attribute
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.segment "ZP2": absolute ; Error, redecl mismatch
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</verb></tscreen>
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See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
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