1 <!doctype linuxdoc system>
4 <title>ld65 Users Guide
5 <author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
6 <date>02.12.2000, 02.10.2001
9 The ld65 linker combines object files into an executable file. ld65 is highly
10 configurable and uses configuration files for high flexibility.
13 <!-- Table of contents -->
16 <!-- Begin the document -->
20 The ld65 linker combines several object modules created by the ca65
21 assembler, producing an executable file. The object modules may be read
22 from a library created by the ar65 archiver (this is somewhat faster and
23 more convenient). The linker was designed to be as flexible as possible.
24 It complements the features that are built into the ca65 macroassembler:
28 <item> Accept any number of segments to form an executable module.
30 <item> Resolve arbitrary expressions stored in the object files.
32 <item> In case of errors, use the meta information stored in the object files
33 to produce helpful error messages. In case of undefined symbols,
34 expression range errors, or symbol type mismatches, ld65 is able to
35 tell you the exact location in the original assembler source, where
36 the symbol was referenced.
38 <item> Flexible output. The output of ld65 is highly configurable by a config
39 file. More common platforms are supported by builtin configurations
40 that may be activated by naming the target system. The output
41 generation was designed with different output formats in mind, so
42 adding other formats shouldn't be a great problem.
50 <sect1>Command line option overview<p>
52 The linker is called as follows:
55 ---------------------------------------------------------------------------
56 Usage: ld65 [options] module ...
58 -C name Use linker config file
59 -L path Specify a library search path
60 -Ln name Create a VICE label file
61 -S addr Set the default start address
62 -V Print the linker version
64 -m name Create a map file
65 -o name Name the default output file
66 -t sys Set the target system
71 --cfg-path path Specify a config file search path
72 --config name Use linker config file
73 --dbgfile name Generate debug information
74 --dump-config name Dump a builtin configuration
75 --help Help (this text)
76 --lib file Link this library
77 --lib-path path Specify a library search path
78 --mapfile name Create a map file
79 --module-id id Specify a module id
80 --obj file Link this object file
81 --obj-path path Specify an object file search path
82 --start-addr addr Set the default start address
83 --target sys Set the target system
84 --version Print the linker version
85 ---------------------------------------------------------------------------
89 <sect1>Command line options in detail<p>
91 Here is a description of all the command line options:
95 <tag><tt>-h, --help</tt></tag>
97 Print the short option summary shown above.
100 <label id="option-m">
101 <tag><tt>-m name, --mapfile name</tt></tag>
103 This option (which needs an argument that will used as a filename for
104 the generated map file) will cause the linker to generate a map file.
105 The map file does contain a detailed overview over the modules used, the
106 sizes for the different segments, and a table containing exported
110 <label id="option-o">
111 <tag><tt>-o name</tt></tag>
113 The -o switch is used to give the name of the default output file.
114 Depending on your output configuration, this name may NOT be used as
115 name for the output file. However, for the builtin configurations, this
116 name is used for the output file name.
119 <label id="option-t">
120 <tag><tt>-t sys, --target sys</tt></tag>
122 The argument for the -t switch is the name of the target system. Since this
123 switch will activate a builtin configuration, it may not be used together
124 with the <tt><ref id="option-C" name="-C"></tt> option. The following target
125 systems are currently supported:
132 <item>c16 (works also for the c116 with memory up to 32K)
136 <item>cbm510 (CBM-II series with 40 column video)
137 <item>cbm610 (all CBM series-II computers with 80 column video)
138 <item>pet (all CBM PET systems except the 2001)
145 There are a few more targets defined but neither of them is actually
149 <label id="option-v">
150 <tag><tt>-v, --verbose</tt></tag>
152 Using the -v option, you may enable more output that may help you to
153 locate problems. If an undefined symbol is encountered, -v causes the
154 linker to print a detailed list of the references (that is, source file
155 and line) for this symbol.
158 <tag><tt>-vm</tt></tag>
160 Must be used in conjunction with <tt><ref id="option-m" name="-m"></tt>
161 (generate map file). Normally the map file will not include empty segments
162 and sections, or unreferenced symbols. Using this option, you can force the
163 linker to include all this information into the map file.
166 <label id="option-C">
167 <tag><tt>-C</tt></tag>
169 This gives the name of an output config file to use. See section 4 for more
170 information about config files. -C may not be used together with <tt><ref
171 id="option-t" name="-t"></tt>.
174 <label id="option--lib-path">
175 <tag><tt>-L path, --lib-path path</tt></tag>
177 Specify a library search path. This option may be used more than once. It
178 adds a directory to the search path for library files. Libraries specified
179 without a path are searched in current directory, in the directory given in
180 the <tt/LD65_LIB/ environment variable, and in the list of directories
181 specified using <tt/--lib-path/.
184 <tag><tt>-Ln</tt></tag>
186 This option allows you to create a file that contains all global labels and
187 may be loaded into VICE emulator using the <tt/ll/ (load label) command. You
188 may use this to debug your code with VICE. Note: Older versions had some
189 bugs in the label code. If you have problems, please get the latest VICE
193 <label id="option-S">
194 <tag><tt>-S addr, --start-addr addr</tt></tag>
196 Using -S you may define the default starting address. If and how this
197 address is used depends on the config file in use. For the builtin
198 configurations, only the "none" system honors an explicit start address,
199 all other builtin config provide their own.
202 <tag><tt>-V, --version</tt></tag>
204 This option print the version number of the linker. If you send any
205 suggestions or bugfixes, please include this number.
208 <label id="option--cfg-path">
209 <tag><tt>--cfg-path path</tt></tag>
211 Specify a config file search path. This option may be used more than once.
212 It adds a directory to the search path for config files. A config file given
213 with the <tt><ref id="option-C" name="-C"></tt> option that has no path in
214 its name is searched in the current directory, in the directory given in the
215 <tt/LD65_CFG/ environment variable, and in the list of directories specified
216 using <tt/--cfg-path/.
219 <label id="option--dbgfile">
220 <tag><tt>--dbgfile name</tt></tag>
222 Specify an output file for debug information. Available information will be
223 written to this file. Using the <tt/-g/ option for the compiler and assembler
224 will increase the amount of information available. Please note that debug
225 information generation is currently being developed, so the format of the
226 file and it's contents are subject to change without further notice.
229 <tag><tt>--lib file</tt></tag>
231 Links a library to the output. Use this command line option instead of just
232 naming the library file, if the linker is not able to determine the file
233 type because of an unusual extension.
236 <tag><tt>--obj file</tt></tag>
238 Links an object file to the output. Use this command line option instead
239 of just naming the object file, if the linker is not able to determine the
240 file type because of an unusual extension.
243 <label id="option--obj-path">
244 <tag><tt>--obj-path path</tt></tag>
246 Specify an object file search path. This option may be used more than once.
247 It adds a directory to the search path for object files. An object file
248 passed to the linker that has no path in its name is searched in current
249 directory, in the directory given in the <tt/LD65_OBJ/ environment variable,
250 and in the list of directories specified using <tt/--obj-path/.
256 <sect>Search paths<p>
258 Starting with version 2.10 there are now several search paths for files needed
259 by the linker: One for libraries, one for object files and one for config
263 <sect1>Library search path<p>
265 The library search path contains in this order:
268 <item>The current directory.
269 <item>A compiled in library path which is often <tt>/usr/lib/cc65/lib</tt> on
271 <item>The value of the environment variable <tt/LD65_LIB/ if it is defined.
272 <item>The value of the environment variable <tt/CC65_LIB/ if it is defined.
273 Please note that use of this environment variable is obsolete and may
274 get removed in future versions.
275 <item>Any directory added with the <tt><ref id="option--lib-path"
276 name="--lib-path"></tt> option on the command line.
280 <sect1>Object file search path<p>
282 The object file search path contains in this order:
285 <item>The current directory.
286 <item>A compiled in directory which is often <tt>/usr/lib/cc65/lib</tt> on
288 <item>The value of the environment variable <tt/LD65_OBJ/ if it is defined.
289 <item>The value of the environment variable <tt/CC65_LIB/ if it is defined.
290 Please note that use of this environment variable is obsolete and may
291 get removed in future versions.
292 <item>Any directory added with the <tt><ref id="option--obj-path"
293 name="--obj-path"></tt> option on the command line.
297 <sect1>Config file search path<p>
299 The config file search path contains in this order:
302 <item>The current directory.
303 <item>A compiled in directory which is often <tt>/usr/lib/cc65/lib</tt> on
305 <item>The value of the environment variable <tt/LD65_CFG/ if it is defined.
306 <item>Any directory added with the <tt><ref id="option--cfg-path"
307 name="--cfg-path"></tt> option on the command line.
312 <sect>Detailed workings<p>
314 The linker does several things when combining object modules:
316 First, the command line is parsed from left to right. For each object file
317 encountered (object files are recognized by a magic word in the header, so
318 the linker does not care about the name), imported and exported
319 identifiers are read from the file and inserted in a table. If a library
320 name is given (libraries are also recognized by a magic word, there are no
321 special naming conventions), all modules in the library are checked if an
322 export from this module would satisfy an import from other modules. All
323 modules where this is the case are marked. If duplicate identifiers are
324 found, the linker issues a warning.
326 This procedure (parsing and reading from left to right) does mean, that a
327 library may only satisfy references for object modules (given directly or from
328 a library) named <em/before/ that library. With the command line
331 ld65 crt0.o clib.lib test.o
334 the module test.o may not contain references to modules in the library
335 clib.lib. If this is the case, you have to change the order of the modules
339 ld65 crt0.o test.o clib.lib
342 Step two is, to read the configuration file, and assign start addresses
343 for the segments and define any linker symbols (see <ref id="config-files"
344 name="Configuration files">).
346 After that, the linker is ready to produce an output file. Before doing that,
347 it checks it's data for consistency. That is, it checks for unresolved
348 externals (if the output format is not relocatable) and for symbol type
349 mismatches (for example a zero page symbol is imported by a module as absolute
352 Step four is, to write the actual target files. In this step, the linker will
353 resolve any expressions contained in the segment data. Circular references are
354 also detected in this step (a symbol may have a circular reference that goes
355 unnoticed if the symbol is not used).
357 Step five is to output a map file with a detailed list of all modules,
358 segments and symbols encountered.
360 And, last step, if you give the <tt><ref id="option-v" name="-v"></tt> switch
361 twice, you get a dump of the segment data. However, this may be quite
362 unreadable if you're not a developer:-)
366 <sect>Configuration files<label id="config-files"><p>
368 Configuration files are used to describe the layout of the output file(s). Two
369 major topics are covered in a config file: The memory layout of the target
370 architecture, and the assignment of segments to memory areas. In addition,
371 several other attributes may be specified.
373 Case is ignored for keywords, that is, section or attribute names, but it is
374 <em/not/ ignored for names and strings.
378 <sect1>Memory areas<p>
380 Memory areas are specified in a <tt/MEMORY/ section. Lets have a look at an
381 example (this one describes the usable memory layout of the C64):
385 RAM1: start = $0800, size = $9800;
386 ROM1: start = $A000, size = $2000;
387 RAM2: start = $C000, size = $1000;
388 ROM2: start = $E000, size = $2000;
392 As you can see, there are two ram areas and two rom areas. The names
393 (before the colon) are arbitrary names that must start with a letter, with
394 the remaining characters being letters or digits. The names of the memory
395 areas are used when assigning segments. As mentioned above, case is
396 significant for these names.
398 The syntax above is used in all sections of the config file. The name
399 (<tt/ROM1/ etc.) is said to be an identifier, the remaining tokens up to the
400 semicolon specify attributes for this identifier. You may use the equal sign
401 to assign values to attributes, and you may use a comma to separate
402 attributes, you may also leave both out. But you <em/must/ use a semicolon to
403 mark the end of the attributes for one identifier. The section above may also
404 have looked like this:
407 # Start of memory section
425 There are of course more attributes for a memory section than just start and
426 size. Start and size are mandatory attributes, that means, each memory area
427 defined <em/must/ have these attributes given (the linker will check that). I
428 will cover other attributes later. As you may have noticed, I've used a
429 comment in the example above. Comments start with a hash mark (`#'), the
430 remainder of the line is ignored if this character is found.
435 Let's assume you have written a program for your trusty old C64, and you would
436 like to run it. For testing purposes, it should run in the <tt/RAM/ area. So
437 we will start to assign segments to memory sections in the <tt/SEGMENTS/
442 CODE: load = RAM1, type = ro;
443 RODATA: load = RAM1, type = ro;
444 DATA: load = RAM1, type = rw;
445 BSS: load = RAM1, type = bss, define = yes;
449 What we are doing here is telling the linker, that all segments go into the
450 <tt/RAM1/ memory area in the order specified in the <tt/SEGMENTS/ section. So
451 the linker will first write the <tt/CODE/ segment, then the <tt/RODATA/
452 segment, then the <tt/DATA/ segment - but it will not write the <tt/BSS/
453 segment. Why? Enter the segment type: For each segment specified, you may also
454 specify a segment attribute. There are five possible segment attributes:
458 wprot same as ro but will be marked as write protected in
459 the VICE label file if -Lp is given
461 bss means that this is an uninitialized segment
462 zp a zeropage segment
465 So, because we specified that the segment with the name BSS is of type bss,
466 the linker knows that this is uninitialized data, and will not write it to an
467 output file. This is an important point: For the assembler, the <tt/BSS/
468 segment has no special meaning. You specify, which segments have the bss
469 attribute when linking. This approach is much more flexible than having one
470 fixed bss segment, and is a result of the design decision to supporting an
471 arbitrary segment count.
473 If you specify "<tt/type = bss/" for a segment, the linker will make sure that
474 this segment does only contain uninitialized data (that is, zeroes), and issue
475 a warning if this is not the case.
477 For a <tt/bss/ type segment to be useful, it must be cleared somehow by your
478 program (this happens usually in the startup code - for example the startup
479 code for cc65 generated programs takes care about that). But how does your
480 code know, where the segment starts, and how big it is? The linker is able to
481 give that information, but you must request it. This is, what we're doing with
482 the "<tt/define = yes/" attribute in the <tt/BSS/ definitions. For each
483 segment, where this attribute is true, the linker will export three symbols.
486 __NAME_LOAD__ This is set to the address where the
488 __NAME_RUN__ This is set to the run address of the
489 segment. We will cover run addresses
491 __NAME_SIZE__ This is set to the segment size.
494 Replace <tt/NAME/ by the name of the segment, in the example above, this would
495 be <tt/BSS/. These symbols may be accessed by your code.
497 Now, as we've configured the linker to write the first three segments and
498 create symbols for the last one, there's only one question left: Where does
499 the linker put the data? It would be very convenient to have the data in a
502 <sect1>Output files<p>
504 We don't have any files specified above, and indeed, this is not needed in a
505 simple configuration like the one above. There is an additional attribute
506 "file" that may be specified for a memory area, that gives a file name to
507 write the area data into. If there is no file name given, the linker will
508 assign the default file name. This is "a.out" or the one given with the
509 <tt><ref id="option-o" name="-o"></tt> option on the command line. Since the
510 default behaviour is ok for our purposes, I did not use the attribute in the
511 example above. Let's have a look at it now.
513 The "file" attribute (the keyword may also be written as "FILE" if you like
514 that better) takes a string enclosed in double quotes (`"') that specifies the
515 file, where the data is written. You may specifiy the same file several times,
516 in that case the data for all memory areas having this file name is written
517 into this file, in the order of the memory areas defined in the <tt/MEMORY/
518 section. Let's specify some file names in the <tt/MEMORY/ section used above:
522 RAM1: start = $0800, size = $9800, file = %O;
523 ROM1: start = $A000, size = $2000, file = "rom1.bin";
524 RAM2: start = $C000, size = $1000, file = %O;
525 ROM2: start = $E000, size = $2000, file = "rom2.bin";
529 The <tt/%O/ used here is a way to specify the default behaviour explicitly:
530 <tt/%O/ is replaced by a string (including the quotes) that contains the
531 default output name, that is, "a.out" or the name specified with the <tt><ref
532 id="option-o" name="-o"></tt> option on the command line. Into this file, the
533 linker will first write any segments that go into <tt/RAM1/, and will append
534 then the segments for <tt/RAM2/, because the memory areas are given in this
535 order. So, for the RAM areas, nothing has really changed.
537 We've not used the ROM areas, but we will do that below, so we give the file
538 names here. Segments that go into <tt/ROM1/ will be written to a file named
539 "rom1.bin", and segments that go into <tt/ROM2/ will be written to a file
540 named "rom2.bin". The name given on the command line is ignored in both cases.
542 Assigning an empty file name for a memory area will discard the data written
545 <sect1>LOAD and RUN addresses (ROMable code)<p>
547 Let us look now at a more complex example. Say, you've successfully tested
548 your new "Super Operating System" (SOS for short) for the C64, and you
549 will now go and replace the ROMs by your own code. When doing that, you
550 face a new problem: If the code runs in RAM, we need not to care about
551 read/write data. But now, if the code is in ROM, we must care about it.
552 Remember the default segments (you may of course specify your own):
556 RODATA read only data
558 BSS uninitialized data, read/write
561 Since <tt/BSS/ is not initialized, we must not care about it now, but what
562 about <tt/DATA/? <tt/DATA/ contains initialized data, that is, data that was
563 explicitly assigned a value. And your program will rely on these values on
564 startup. Since there's no other way to remember the contents of the data
565 segment, than storing it into one of the ROMs, we have to put it there. But
566 unfortunately, ROM is not writeable, so we have to copy it into RAM before
567 running the actual code.
569 The linker cannot help you copying the data from ROM into RAM (this must be
570 done by the startup code of your program), but it has some features that will
571 help you in this process.
573 First, you may not only specify a "<tt/load/" attribute for a segment, but
574 also a "<tt/run/" attribute. The "<tt/load/" attribute is mandatory, and, if
575 you don't specify a "<tt/run/" attribute, the linker assumes that load area
576 and run area are the same. We will use this feature for our data area:
580 CODE: load = ROM1, type = ro;
581 RODATA: load = ROM2, type = ro;
582 DATA: load = ROM2, run = RAM2, type = rw, define = yes;
583 BSS: load = RAM2, type = bss, define = yes;
587 Let's have a closer look at this <tt/SEGMENTS/ section. We specify that the
588 <tt/CODE/ segment goes into <tt/ROM1/ (the one at $A000). The readonly data
589 goes into <tt/ROM2/. Read/write data will be loaded into <tt/ROM2/ but is run
590 in <tt/RAM2/. That means that all references to labels in the <tt/DATA/
591 segment are relocated to be in <tt/RAM2/, but the segment is written to
592 <tt/ROM2/. All your startup code has to do is, to copy the data from it's
593 location in <tt/ROM2/ to the final location in <tt/RAM2/.
595 So, how do you know, where the data is located? This is the second point,
596 where you get help from the linker. Remember the "<tt/define/" attribute?
597 Since we have set this attribute to true, the linker will define three
598 external symbols for the data segment that may be accessed from your code:
601 __DATA_LOAD__ This is set to the address where the segment
602 is loaded, in this case, it is an address in
604 __DATA_RUN__ This is set to the run address of the segment,
605 in this case, it is an address in RAM2.
606 __DATA_SIZE__ This is set to the segment size.
609 So, what your startup code must do, is to copy <tt/__DATA_SIZE__/ bytes from
610 <tt/__DATA_LOAD__/ to <tt/__DATA_RUN__/ before any other routines are called.
611 All references to labels in the <tt/DATA/ segment are relocated to <tt/RAM2/
612 by the linker, so things will work properly.
615 <sect1>Other MEMORY area attributes<p>
617 There are some other attributes not covered above. Before starting the
618 reference section, I will discuss the remaining things here.
620 You may request symbols definitions also for memory areas. This may be
621 useful for things like a software stack, or an i/o area.
625 STACK: start = $C000, size = $1000, define = yes;
629 This will define three external symbols that may be used in your code:
632 __STACK_START__ This is set to the start of the memory
633 area, $C000 in this example.
634 __STACK_SIZE__ The size of the area, here $1000.
635 __STACK_LAST__ This is NOT the same as START+SIZE.
636 Instead, it it defined as the first
637 address that is not used by data. If we
638 don't define any segments for this area,
639 the value will be the same as START.
642 A memory section may also have a type. Valid types are
645 ro for readonly memory
646 rw for read/write memory.
649 The linker will assure, that no segment marked as read/write or bss is put
650 into a memory area that is marked as readonly.
652 Unused memory in a memory area may be filled. Use the "<tt/fill = yes/"
653 attribute to request this. The default value to fill unused space is zero. If
654 you don't like this, you may specify a byte value that is used to fill these
655 areas with the "<tt/fillval/" attribute. This value is also used to fill unfilled
656 areas generated by the assemblers <tt/.ALIGN/ and <tt/.RES/ directives.
659 <sect1>Other SEGMENT attributes<p>
661 Segments may be aligned to some memory boundary. Specify "<tt/align = num/" to
662 request this feature. Num must be a power of two. To align all segments on a
667 CODE: load = ROM1, type = ro, align = $100;
668 RODATA: load = ROM2, type = ro, align = $100;
669 DATA: load = ROM2, run = RAM2, type = rw, define = yes,
671 BSS: load = RAM2, type = bss, define = yes, align = $100;
675 If an alignment is requested, the linker will add enough space to the output
676 file, so that the new segment starts at an address that is divideable by the
677 given number without a remainder. All addresses are adjusted accordingly. To
678 fill the unused space, bytes of zero are used, or, if the memory area has a
679 "<tt/fillval/" attribute, that value. Alignment is always needed, if you have
680 the used the <tt/.ALIGN/ command in the assembler. The alignment of a segment
681 must be equal or greater than the alignment used in the <tt/.ALIGN/ command.
682 The linker will check that, and issue a warning, if the alignment of a segment
683 is lower than the alignment requested in a <tt/.ALIGN/ command of one of the
684 modules making up this segment.
686 For a given segment you may also specify a fixed offset into a memory area or
687 a fixed start address. Use this if you want the code to run at a specific
688 address (a prominent case is the interrupt vector table which must go at
689 address $FFFA). Only one of <tt/ALIGN/ or <tt/OFFSET/ or <tt/START/ may be
690 specified. If the directive creates empty space, it will be filled with zero,
691 of with the value specified with the "<tt/fillval/" attribute if one is given.
692 The linker will warn you if it is not possible to put the code at the
693 specified offset (this may happen if other segments in this area are too
694 large). Here's an example:
698 VECTORS: load = ROM2, type = ro, start = $FFFA;
702 or (for the segment definitions from above)
706 VECTORS: load = ROM2, type = ro, offset = $1FFA;
710 To suppress the warning, the linker issues if it encounters a segment that is
711 not found in any of the input files, use "<tt/optional=yes/" as additional
712 segment attribute. Be careful when using this attribute, because a missing
713 segment may be a sign of a problem, and if you're suppressing the warning,
714 there is no one left to tell you about it.
716 File names may be empty, data from segments assigned to a memory area with
717 an empty file name is discarded. This is useful, if the a memory area has
718 segments assigned that are empty (for example because they are of type
719 bss). In that case, the linker will create an empty output file. This may
720 be suppressed by assigning an empty file name to that memory area.
722 The symbol <tt/%S/ may be used to access the default start address (that is,
723 $200 or the value given on the command line with the <tt><ref id="option-S"
724 name="-S"></tt> option).
728 <sect1>The FILES section<p>
730 The <tt/FILES/ section is used to support other formats than straight binary
731 (which is the default, so binary output files do not need an explicit entry
732 in the <tt/FILES/ section).
734 The <tt/FILES/ section lists output files and as only attribute the format of
735 each output file. Assigning binary format to the default output file would
744 The only other available output format is the o65 format specified by Andre
745 Fachat. It is defined like this:
753 The necessary o65 attributes are defined in a special section labeled
758 <sect1>The FORMAT section<p>
760 The <tt/FORMAT/ section is used to describe file formats. The default (binary)
761 format has currently no attributes, so, while it may be listed in this
762 section, the attribute list is empty. The second supported format, o65, has
763 several attributes that may be defined here.
767 o65: os = lunix, version = 0, type = small,
768 import = LUNIXKERNEL,
779 In addition to the <tt/MEMORY/ and <tt/SEGMENTS/ sections described above, the
780 linker has features that may be enabled by an additional section labeled
781 <tt/FEATURES/. Currently, one such feature is available: <tt/CONDES/ is used
782 to tell the linker to emit module constructor/destructor tables.
786 CONDES: segment = RODATA,
788 label = __CONSTRUCTOR_TABLE__,
789 count = __CONSTRUCTOR_COUNT__;
793 The <tt/CONDES/ feature has several attributes:
797 <tag><tt>segment</tt></tag>
799 This attribute tells the linker into which segment the table should be
800 placed. If the segment does not exist, it is created.
803 <tag><tt>type</tt></tag>
805 Describes the type of the routines to place in the table. Type may be
806 one of the predefined types <tt/constructor/ or <tt/destructor/, or a
807 numeric value between 0 and 6.
810 <tag><tt>label</tt></tag>
812 This specifies the label to use for the table. The label points to the
813 start of the table in memory and may be used from within user written
817 <tag><tt>count</tt></tag>
819 This is an optional attribute. If specified, an additional symbol is
820 defined by the linker using the given name. The value of this symbol
821 is the number of entries (<em/not/ bytes) in the table. While this
822 attribute is optional, it is often useful to define it.
825 <tag><tt>order</tt></tag>
827 Optional attribute that takes one of the keywords <tt/increasing/ or
828 <tt/decreasing/ as an argument. Specifies the sorting order of the entries
829 within the table. The default is <tt/increasing/, which means that the
830 entries are sorted with increasing priority (the first entry has the lowest
831 priority). "Priority" is the priority specified when declaring a symbol as
832 <tt/.CONDES/ with the assembler, higher values mean higher priority. You may
833 change this behaviour by specifying <tt/decreasing/ as the argument, the
834 order of entries is reversed in this case.
836 Please note that the order of entries with equal priority is undefined.
840 Without specifying the <tt/CONDES/ feature, the linker will not create any
841 tables, even if there are <tt/condes/ entries in the object files.
843 For more information see the <tt/.CONDES/ command in the <htmlurl
844 url="ca65.html" name="ca65 manual">.
848 <sect1>Builtin configurations<p>
850 The builtin configurations are part of the linker source. They are also
851 distributed together with the machine specific binary packages (usually in the
852 doc directory) and don't have a special format. So if you need a special
853 configuration, it's a good idea to start with the builtin configuration for
854 your system. In a first step, just replace <tt/-t target/ by <tt/-C
855 configfile/. The go on and modify the config file to suit your needs.
859 <sect>Bugs/Feedback<p>
861 If you have problems using the linker, if you find any bugs, or if you're
862 doing something interesting with it, I would be glad to hear from you. Feel
863 free to contact me by email (<htmlurl url="mailto:uz@cc65.org"
864 name="uz@cc65.org">).
870 ld65 (and all cc65 binutils) are (C) Copyright 1998-2001 Ullrich von
871 Bassewitz. For usage of the binaries and/or sources the following
874 This software is provided 'as-is', without any expressed or implied
875 warranty. In no event will the authors be held liable for any damages
876 arising from the use of this software.
878 Permission is granted to anyone to use this software for any purpose,
879 including commercial applications, and to alter it and redistribute it
880 freely, subject to the following restrictions:
883 <item> The origin of this software must not be misrepresented; you must not
884 claim that you wrote the original software. If you use this software
885 in a product, an acknowledgment in the product documentation would be
886 appreciated but is not required.
887 <item> Altered source versions must be plainly marked as such, and must not
888 be misrepresented as being the original software.
889 <item> This notice may not be removed or altered from any source