-<!doctype linuxdoc system>
+<!doctype linuxdoc system> <!-- -*- text-mode -*- -->
<article>
<title>ld65 Users Guide
-m name Create a map file
-o name Name the default output file
-t sys Set the target system
+ -u sym Force an import of symbol `sym'
-v Verbose mode
-vm Verbose map file
--define sym=val Define a symbol
--dump-config name Dump a builtin configuration
--end-group End a library group
+ --force-import sym Force an import of symbol `sym'
--help Help (this text)
--lib file Link this library
--lib-path path Specify a library search path
<itemize>
<item>none
+ <item>module
<item>apple2
<item>apple2enh
<item>atari
<item>c16 (works also for the c116 with memory up to 32K)
<item>c64
<item>c128
- <item>plus4
<item>cbm510 (CBM-II series with 40 column video)
<item>cbm610 (all CBM series-II computers with 80 column video)
- <item>pet (all CBM PET systems except the 2001)
- <item>geos
+ <item>geos-apple
+ <item>geos-cbm
<item>lunix
- <item>atmos
+ <item>lynx
<item>nes
+ <item>pet (all CBM PET systems except the 2001)
+ <item>plus4
<item>supervision
+ <item>vic20
</itemize>
There are a few more targets defined but neither of them is actually
supported.
+ <tag><tt>-u sym[:addrsize], --force-import sym[:addrsize]</tt></tag>
+
+ Force an import of a symbol. While object files are always linked to the
+ output file, regardless if there are any references, object modules from
+ libraries get only linked in if an import can be satisfied by this module.
+ The <tt/--fore-import/ option may be used to add a reference to a symbol and
+ as a result force linkage of the module that exports the identifier.
+
+ The name of the symbol may optionally be followed by a colon and an address
+ size specifier. If no address size is specified, the default address size
+ for the target machine is used.
+
+ Please note that the symbol name needs to have the internal representation,
+ meaning you have to prepend an underline for C identifiers.
+
+
<label id="option-v">
<tag><tt>-v, --verbose</tt></tag>
written to this file. Using the <tt/-g/ option for the compiler and assembler
will increase the amount of information available. Please note that debug
information generation is currently being developed, so the format of the
- file and it's contents are subject to change without further notice.
+ file and its contents are subject to change without further notice.
<tag><tt>--lib file</tt></tag>
<item>A compiled in library path which is often <tt>/usr/lib/cc65/lib</tt> on
Linux systems.
<item>The value of the environment variable <tt/LD65_LIB/ if it is defined.
-<item>The value of the environment variable <tt/CC65_LIB/ if it is defined.
- Please note that use of this environment variable is obsolete and may
- get removed in future versions.
+<item>A subdirectory named <tt/lib/ of the directory defined in the environment
+ variable <tt/CC65_HOME/, if it is defined.
<item>Any directory added with the <tt><ref id="option--lib-path"
name="--lib-path"></tt> option on the command line.
</enum>
<enum>
<item>The current directory.
-<item>A compiled in directory which is often <tt>/usr/lib/cc65/lib</tt> on
+<item>A compiled in directory which is often <tt>/usr/lib/cc65/obj</tt> on
Linux systems.
<item>The value of the environment variable <tt/LD65_OBJ/ if it is defined.
-<item>The value of the environment variable <tt/CC65_LIB/ if it is defined.
- Please note that use of this environment variable is obsolete and may
- get removed in future versions.
+<item>A subdirectory named <tt/obj/ of the directory defined in the environment
+ variable <tt/CC65_HOME/, if it is defined.
<item>Any directory added with the <tt><ref id="option--obj-path"
name="--obj-path"></tt> option on the command line.
</enum>
<enum>
<item>The current directory.
-<item>A compiled in directory which is often <tt>/usr/lib/cc65/lib</tt> on
+<item>A compiled in directory which is often <tt>/usr/lib/cc65/cfg</tt> on
Linux systems.
<item>The value of the environment variable <tt/LD65_CFG/ if it is defined.
+<item>A subdirectory named <tt/cfg/ of the directory defined in the environment
+ variable <tt/CC65_HOME/, if it is defined.
<item>Any directory added with the <tt><ref id="option--cfg-path"
name="--cfg-path"></tt> option on the command line.
</enum>
name="Configuration files">).
After that, the linker is ready to produce an output file. Before doing that,
-it checks it's data for consistency. That is, it checks for unresolved
+it checks its data for consistency. That is, it checks for unresolved
externals (if the output format is not relocatable) and for symbol type
mismatches (for example a zero page symbol is imported by a module as absolute
symbol).
named "rom2.bin". The name given on the command line is ignored in both cases.
Assigning an empty file name for a memory area will discard the data written
-to it. This is useful, if the a memory area has segments assigned that are
-empty (for example because they are of type bss). In that case, the linker
-will create an empty output file. This may be suppressed by assigning an empty
-file name to that memory area.
+to it. This is useful, if the memory area has segments assigned that are empty
+(for example because they are of type bss). In that case, the linker will
+create an empty output file. This may be suppressed by assigning an empty file
+name to that memory area.
+The <tt/%O/ sequence is also allowed inside a string. So using
+
+<tscreen><verb>
+ MEMORY {
+ ROM1: start = $A000, size = $2000, file = "%O-1.bin";
+ ROM2: start = $E000, size = $2000, file = "%O-2.bin";
+ }
+</verb></tscreen>
+
+would write two files that start with the name of the output file specified on
+the command line, with "-1.bin" and "-2.bin" appended respectively. Because
+'%' is used as an escape char, the sequence "%%" has to be used if a single
+percent sign is required.
<sect1>LOAD and RUN addresses (ROMable code)<p>
unfortunately, ROM is not writable, so we have to copy it into RAM before
running the actual code.
-The linker cannot help you copying the data from ROM into RAM (this must be
-done by the startup code of your program), but it has some features that will
-help you in this process.
+The linker won't copy the data from ROM into RAM for you (this must be done by
+the startup code of your program), but it has some features that will help you
+in this process.
First, you may not only specify a "<tt/load/" attribute for a segment, but
also a "<tt/run/" attribute. The "<tt/load/" attribute is mandatory, and, if
goes into <tt/ROM2/. Read/write data will be loaded into <tt/ROM2/ but is run
in <tt/RAM2/. That means that all references to labels in the <tt/DATA/
segment are relocated to be in <tt/RAM2/, but the segment is written to
-<tt/ROM2/. All your startup code has to do is, to copy the data from it's
+<tt/ROM2/. All your startup code has to do is, to copy the data from its
location in <tt/ROM2/ to the final location in <tt/RAM2/.
So, how do you know, where the data is located? This is the second point,
All references to labels in the <tt/DATA/ segment are relocated to <tt/RAM2/
by the linker, so things will work properly.
+There's a library subroutine called <tt/copydata/ (in a module named
+<tt/copydata.s/) that might be used to do actual copying. Be sure to have a
+look at it's inner workings before using it!
+
<sect1>Other MEMORY area attributes<p>
}
</verb></tscreen>
-This will define three external symbols that may be used in your code:
+This will define some external symbols that may be used in your code:
<tscreen><verb>
__STACK_START__ This is set to the start of the memory
- area, $C000 in this example.
+ area, $C000 in this example.
__STACK_SIZE__ The size of the area, here $1000.
__STACK_LAST__ This is NOT the same as START+SIZE.
- Instead, it it defined as the first
- address that is not used by data. If we
- don't define any segments for this area,
- the value will be the same as START.
+ Instead, it it defined as the first
+ address that is not used by data. If we
+ don't define any segments for this area,
+ the value will be the same as START.
+ __STACK_FILEOFFS__ The binary offset in the output file. This
+ is not defined for relocatable output file
+ formats (o65).
</verb></tscreen>
A memory section may also have a type. Valid types are
Unused memory in a memory area may be filled. Use the "<tt/fill = yes/"
attribute to request this. The default value to fill unused space is zero. If
you don't like this, you may specify a byte value that is used to fill these
-areas with the "<tt/fillval/" attribute. This value is also used to fill unfilled
-areas generated by the assemblers <tt/.ALIGN/ and <tt/.RES/ directives.
+areas with the "<tt/fillval/" attribute. If there is no "<tt/fillval/"
+attribute for the segment, the "<tt/fillval/" attribute of the memory area (or
+its default) is used instead. This means that the value may also be used to
+fill unfilled areas generated by the assemblers <tt/.ALIGN/ and <tt/.RES/
+directives.
The symbol <tt/%S/ may be used to access the default start address (that is,
the one defined in the <ref id="FEATURES" name="FEATURES"> section, or the
value given on the command line with the <tt><ref id="option-S" name="-S"></tt>
option).
+To support systems with banked memory, a special attribute named <tt/bank/ is
+available. The attribute value is an arbitrary 32 bit integer. The assembler
+has a builtin function named <tt/.BANK/ which may be used with an argument
+that has a segment reference (for example a symbol). The result of this
+function is the value of the bank attribute for the run memory area of the
+segment.
+
<sect1>Other SEGMENT attributes<p>
been specified. There are no special attributes to set start or offset for
just the load memory area.
+A "<tt/fillval/" attribute may not only be specified for a memory area, but
+also for a segment. The value must be an integer between 0 and 255. It is used
+as fill value for space reserved by the assemblers <tt/.ALIGN/ and <tt/.RES/
+commands. It is also used as fill value for space between sections (part of a
+segment that comes from one object file) caused by alignment, but not for
+space that preceeds the first section.
+
To suppress the warning, the linker issues if it encounters a segment that is
not found in any of the input files, use "<tt/optional=yes/" as additional
segment attribute. Be careful when using this attribute, because a missing
The <tt/FORMAT/ section is used to describe file formats. The default (binary)
format has currently no attributes, so, while it may be listed in this
-section, the attribute list is empty. The second supported format, o65, has
-several attributes that may be defined here.
+section, the attribute list is empty. The second supported format,
+<htmlurl url="http://www.6502.org/users/andre/o65/fileformat.html" name="o65">,
+has several attributes that may be defined here.
<tscreen><verb>
FORMATS {
Please note that the order of entries with equal priority is undefined.
+ <tag><tt>import</tt></tag>
+
+ This attribute defines a valid symbol name, that is added as an import
+ to the modules defining a constructor/desctructor of the given type.
+ This can be used to force linkage of a module if this module exports the
+ requested symbol.
+
</descrip>
Without specifying the <tt/CONDES/ feature, the linker will not create any
<sect1>The SYMBOLS section<label id="SYMBOLS"><p>
The configuration file may also be used to define symbols used in the link
-stage. The mandatory attribute for a symbol is its value. A second, boolean
-attribute named <tt/weak/ is available. If a symbol is marked as weak, it may
-be overridden by defining a symbol of the same name from the command line. The
-default for symbols is that they're strong, which means that an attempt to
-define a symbol with the same name from the command line will lead to an
-error.
+stage or to force symbols imports. This is done in the SYMBOLS section. The
+symbol name is followed by a colon and symbol attributes.
+
+The following symbol attributes are supported:
+
+<descrip>
+
+ <tag><tt>addrsize</tt></tag>
+
+ The <tt/addrsize/ attribute specifies the address size of the symbol and
+ may be one of
+<itemize>
+ <item><tt/zp/, <tt/zeropage/ or <tt/direct/
+ <item><tt/abs/, <tt/absolute/ or <tt/near/
+ <item><tt/far/
+ <item><tt/long/ or <tt/dword/.
+</itemize>
+
+Without this attribute, the default address size is <tt/abs/.
+
+ <tag><tt>type</tt></tag>
+
+ This attribute is mandatory. Its value is one of <tt/export/, <tt/import/ or
+ <tt/weak/. <tt/export/ means that the symbol is defined and exported from
+ the linker config. <tt/import/ means that an import is generated for this
+ symbol, eventually forcing a module that exports this symbol to be included
+ in the output. <tt/weak/ is similar as <tt/export/. However, the symbol is
+ only defined if it is not defined elsewhere.
+
+ <tag><tt>value</tt></tag>
+
+ This must only be given for symbols of type <tt/export/ or <tt/weak/. It
+ defines the value of the symbol and may be an expression.
+
+</descrip>
The following example defines the stack size for an application, but allows
the programmer to override the value by specifying <tt/--define
<tscreen><verb>
SYMBOLS {
# Define the stack size for the application
- __STACKSIZE__: value = $800, weak = yes;
+ __STACKSIZE__: type = weak, value = $800;
}
</verb></tscreen>
<sect1>Builtin configurations<p>
-The builtin configurations are part of the linker source. They are also
-distributed together with the machine specific binary packages (usually in the
-doc directory) and don't have a special format. So if you need a special
-configuration, it's a good idea to start with the builtin configuration for
-your system. In a first step, just replace <tt/-t target/ by <tt/-C
+The builtin configurations are part of the linker source. They can be retrieved
+with <tt/--dump-config/ and don't have a special format. So if you need a
+special configuration, it's a good idea to start with the builtin configuration
+for your system. In a first step, just replace <tt/-t target/ by <tt/-C
configfile/. Then go on and modify the config file to suit your needs.
+<sect1>Secondary configurations<p>
+
+Several machine specific binary packages are distributed together with secondary
+configurations (in the cfg directory). These configurations can be used with
+<tt/-C configfile/ too.
+
+
+
<sect>Special segments<p>
The builtin config files do contain segments that have a special meaning for
and the libraries. It is placed in its own segment because it needs to be
loaded at the lowest possible program address on several platforms.
-This segment defines the location of the memory heap used by the malloc
-routine.
+The ZPSAVE segment contains the original values of the zeropage locations used
+by the ZEROPAGE segment. It is placed in its own segment because it must not be
+initialized.
projects / cc65 / blobdiff