GP2X Static Library Creation


Keith

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Hi, I have been trying and failing to create a static library that wraps the GP2X functionality and which I can then use in other projects. I am using Visual Studio 2005 with the rules file from the Wiki. In the WIKI it talks about how to create a static library but it does not work for me - it just tries to do a normal link. Does anyone know how I can create a .lib (or is it .a?) ?

thanks
 

gmiller1018

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The "ar" utility ("arm-linux-ar") will create a library of object files that you can link against. From the command line you could do the following to add all of the object files in the current directory to a library call fubar.a:

arm-linux-ar rv fubar.a *.o

This example "replaces the object files in the library (adds if not there). If the library is not there there may be a warning message. If you want to force a library creation use 'c' in the 'rv' switch value ("rcv"). Of course replacement on a new library does not seem correct so you could just use 'a'dd instead of 'r'place. If you use add then you generally get an error trying to add an object file that is already there.

The man page for ar is as follows:
Code:
SYNOPSIS
	   ar [-X32_64] [-]p[mod [relpos] [count]] archive [member...]

DESCRIPTION
	   The  GNU  ar program creates, modifies, and extracts from archives.  An
	   archive is a single file holding a  collection  of  other  files  in  a
	   structure  that  makes  it possible to retrieve the original individual
	   files (called members of the archive).

	   The original files' contents, mode (permissions), timestamp, owner, and
	   group  are preserved in the archive, and can be restored on extraction.

	   GNU ar can maintain archives whose members have names  of  any  length;
	   however,  depending  on how ar is configured on your system, a limit on
	   member-name length  may  be  imposed  for  compatibility  with  archive
	   formats  maintained with other tools.  If it exists, the limit is often
	   15 characters (typical of formats related to a.out)  or  16  characters
	   (typical of formats related to coff).

	   ar  is  considered  a  binary utility because archives of this sort are
	   most often used as libraries holding commonly needed subroutines.

	   ar creates an index  to  the  symbols  defined  in  relocatable  object
	   modules  in the archive when you specify the modifier s.  Once created,
	   this index is updated in the archive whenever ar makes a change to  its
	   contents  (save  for  the q update operation).  An archive with such an
	   index speeds up linking to the library,  and  allows  routines  in  the
	   library  to  call  each  other without regard to their placement in the
	   archive.

	   You may use nm -s or nm --print-armap to list this index table.  If  an
	   archive  lacks  the table, another form of ar called ranlib can be used
	   to add just the table.

	   GNU ar is designed to be compatible with two different facilities.  You
	   can control its activity using command-line options, like the different
	   varieties of ar on Unix systems; or, if you specify the single command-
	   line  option -M, you can control it with a script supplied via standard
	   input, like the MRI ``librarian' program.

OPTIONS
	   GNU ar allows you to mix the operation code p and modifier flags mod in
	   any order, within the first command-line argument.

	   If you wish, you may begin the first command-line argument with a dash.

	   The p keyletter specifies what operation to execute; it may be  any  of
	   the following, but you must specify only one of them:

	   d   Delete  modules  from the archive.  Specify the names of modules to
		   be deleted as member...; the archive is untouched if you specify no
		   files to delete.

		   If  you  specify  the  v  modifier,  ar  lists each module as it is
		   deleted.

	   m   Use this operation to move members in an archive.

		   The ordering of members in an archive can make a difference in  how
		   programs  are  linked  using the library, if a symbol is defined in
		   more than one member.

		   If no modifiers are used with m, any members you name in the member
		   arguments  are  moved to the end of the archive; you can use the a,
		   b, or i modifiers to move them to a specified place instead.

	   p   Print the specified members of the archive, to the standard  output
		   file.   If the v modifier is specified, show the member name before
		   copying its contents to standard output.

		   If you specify no member arguments, all the files  in  the  archive
		   are printed.

	   q   Quick  append;  Historically, add the files member... to the end of
		   archive, without checking for replacement.

		   The modifiers a, b, and i do not affect this operation; new members
		   are always placed at the end of the archive.

		   The modifier v makes ar list each file as it is appended.

		   Since  the  point  of this operation is speed, the archive's symbol
		   table index is not updated, even if it already existed; you can use
		   ar s or ranlib explicitly to update the symbol table index.

		   However,  too  many  different systems assume quick append rebuilds
		   the index, so GNU ar implements q as a synonym for r.

	   r   Insert the files member... into archive  (with  replacement).  This
		   operation  differs  from  q in that any previously existing members
		   are deleted if their names match those being added.

		   If one of the files named in member... does not exist, ar  displays
		   an  error  message,  and leaves undisturbed any existing members of
		   the archive matching that name.

		   By default, new members are added at the end of the file;  but  you
		   may  use  one  of  the  modifiers  a,  b, or i to request placement
		   relative to some existing member.

		   The modifier v used with this operation elicits a  line  of  output
		   for  each  file  inserted,  along with one of the letters a or r to
		   indicate whether the file was appended (no old member  deleted)  or
		   replaced.

	   t   Display  a  table  listing the contents of archive, or those of the
		   files  listed  in  member...  that  are  present  in  the  archive.
		   Normally only the member name is shown; if you also want to see the
		   modes (permissions), timestamp, owner, group,  and  size,  you  can
		   request that by also specifying the v modifier.

		   If  you  do  not  specify  a  member,  all files in the archive are
		   listed.

		   If there is more than one file with the same name (say, fie) in  an
		   archive  (say  b.a), ar t b.a fie lists only the first instance; to
		   see them all, you must ask for a complete listing---in our example,
		   ar t b.a.

	   x   Extract members (named member) from the archive.  You can use the v
		   modifier with this operation, to request that ar list each name  as
		   it extracts it.

		   If  you  do  not  specify  a  member,  all files in the archive are
		   extracted.

	   A number of modifiers (mod) may immediately follow the p keyletter,  to
	   specify variations on an operation's behavior:

	   a   Add  new files after an existing member of the archive.  If you use
		   the modifier a, the name of an  existing  archive  member  must  be
		   present as the relpos argument, before the archive specification.

	   b   Add new files before an existing member of the archive.  If you use
		   the modifier b, the name of an  existing  archive  member  must  be
		   present  as  the relpos argument, before the archive specification.
		   (same as i).

	   c   Create the archive.  The specified archive is always created if  it
		   did not exist, when you request an update.  But a warning is issued
		   unless you specify in advance that you  expect  to  create  it,  by
		   using this modifier.

	   f   Truncate  names  in  the archive.  GNU ar will normally permit file
		   names of any length.  This will cause it to create  archives  which
		   are  not compatible with the native ar program on some systems.  If
		   this is a concern, the f modifier may  be  used  to  truncate  file
		   names when putting them in the archive.

	   i   Insert  new files before an existing member of the archive.  If you
		   use the modifier i, the name of an existing archive member must  be
		   present  as  the relpos argument, before the archive specification.
		   (same as b).

	   l   This modifier is accepted but not used.

	   N   Uses the count parameter.  This  is  used  if  there  are  multiple
		   entries  in  the  archive  with  the  same name.  Extract or delete
		   instance count of the given name from the archive.

	   o   Preserve the original dates of members when  extracting  them.   If
		   you  do not specify this modifier, files extracted from the archive
		   are stamped with the time of extraction.

	   P   Use the full path name when matching names in the archive.  GNU  ar
		   can  not create an archive with a full path name (such archives are
		   not POSIX complaint), but other archive creators can.  This  option
		   will  cause  GNU ar to match file names using a complete path name,
		   which can be convenient when  extracting  a  single  file  from  an
		   archive created by another tool.

	   s   Write  an object-file index into the archive, or update an existing
		   one, even if no other change is made to the archive.  You  may  use
		   this modifier flag either with any operation, or alone.  Running ar
		   s on an archive is equivalent to running ranlib on it.

	   S   Do not generate  an  archive  symbol  table.   This  can  speed  up
		   building  a  large library in several steps.  The resulting archive
		   can not be used with the linker.  In order to build a symbol table,
		   you  must  omit  the S modifier on the last execution of ar, or you
		   must run ranlib on the archive.

	   u   Normally, ar r... inserts all files listed into  the  archive.   If
		   you  would like to insert only those of the files you list that are
		   newer than existing members of the same names, use  this  modifier.
		   The  u  modifier is allowed only for the operation r (replace).  In
		   particular, the combination qu is not allowed, since  checking  the
		   timestamps would lose any speed advantage from the operation q.

	   v   This  modifier  requests the verbose version of an operation.  Many
		   operations  display  additional  information,  such  as   filenames
		   processed, when the modifier v is appended.

	   V   This modifier shows the version number of ar.

	   ar ignores an initial option spelt -X32_64, for compatibility with AIX.
	   The behaviour produced by this option is the default for  GNU  ar.   ar
	   does  not  support  any of the other -X options; in particular, it does
	   not support -X32 which is the default for AIX ar.

SEE ALSO
	   nm(1), ranlib(1), and the Info entries for binutils.

COPYRIGHT
	   Copyright (c) 1991, 1992, 1993, 1994, 1995,  1996,  1997,  1998,  1999,
	   2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.

	   Permission  is  granted to copy, distribute and/or modify this document
	   under the terms of the GNU Free Documentation License, Version  1.1  or
	   any  later  version  published by the Free Software Foundation; with no
	   Invariant Sections, with no Front-Cover Texts, and with  no  Back-Cover
	   Texts.  A copy of the license is included in the section entitled ``GNU
	   Free Documentation License'.

3rd Berkeley Distribution	  binutils-2.16.91						  AR(1)
 
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slygamer

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Hi, I have been trying and failing to create a static library that wraps the GP2X functionality and which I can then use in other projects. I am using Visual Studio 2005 with the rules file from the Wiki. In the WIKI it talks about how to create a static library but it does not work for me - it just tries to do a normal link. Does anyone know how I can create a .lib (or is it .a?) ?

thanks

Did you follow each step exactly as in the wiki? Most importantly, the step in bold.

1. Check the Custom Build Rules dialog (right-click on the project name) and make sure that the GCC Compiler rule is enabled.
2. Open the project properties for LibProject1.
3. On the General page under Configuration Properties, set the Output Directory property to $(SolutionDir)lib. This will place the .a files in the lib directory of the solution.
4. Add *.o to the Extensions to Delete on Clean property.
5. Just below that in Project Defaults, change Configuration Type to Static Library (.lib). Now you will need to hit the Apply button because this changes some of the other property pages.
6. There should now be a Librarian property page. Select this and change the Output File property to $(OutDir)\libxxxd.a where xxx is the name you wish to give your library. The d is a naming convention for debug versions of libraries (omit the d for release configurations), and naming conventions also state that the library name starts with lib and ends in .a.
7. Skip down to the GCC Compiler property page and set any properties here that you may require, such as additional include paths.
8. Click the Ok button and open the Tool Build Order dialog (right-click on the project name).
9. Select each project in turn in the Projects combobox and tick the projects in the Depends on list that the project is dependent on.
 
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Keith

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Hi, thanks for the info Gary - I may go that way if I cannot get it to work in Viz. Slygamer - I have indeed followed those steps and it is definately set to a Static Library. Step 8 confuses me as there seems to be no action - just open the Tool Build Order - I tried moving the archiver up the list but to no effect.
 

gmiller1018

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I am a command line junkie so I tend to avoid GUI application that hide too much. But I have been doing this a long time, and I do use GUI apps for some things. I take the approach that if the app save me aggravation and simplifies repetitive operation then I will use it. If it makes things more complex then "forget it and do it by hand"
 

Keith

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True but this library is something I have for the PC, PocketPC, Mobile Phone and now GP2X and so it is nice to have all the configurations in one VIS solution. Makes it easy to work with hence it would be a shame if I had to use a different method just for the GP2x.
 

gmiller1018

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Then you just need a little more understanding of the tool to make it work. It takes more work to create a shared library than a static so this should be more understanding on how not to do things than do things.

Good luck ..
 

slygamer

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Hi, thanks for the info Gary - I may go that way if I cannot get it to work in Viz. Slygamer - I have indeed followed those steps and it is definately set to a Static Library. Step 8 confuses me as there seems to be no action - just open the Tool Build Order - I tried moving the archiver up the list but to no effect.
Hmm... ok. Looks like I left out a step there. I will work it out when I get home tonight because I am in the process of setting up a new PC to build GP2X applications, so I will be going through the steps anyway.
 
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Keith

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Sly- just wondered if you had any more ideas about this - I have still not managed to get it to work in Viz although I can create .a files from a command line.
 

slygamer

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Sorry. I got snowed under by meeting a deadline at work.

I'm just re-installing VC++ 2005 Express on my machine now, but I thought I would take a look at the history on the wiki page, and sure enough there were a couple of lines that had been deleted previously (as part of a mass deletion by someone at some point). I have restored the missing steps, so now you should be able to get it working.
 

Keith

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Aha thanks! The addition of the file to trigger the archiver could be exactly what I was missing - I will give it a go
 

Keith

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Gave it a go and after a painful period of getting paths etc. set up correctly and a few other gotchas I now have it all working: it creates the .a file then builds a test project and links to the .a and I get a gpe! Problems along the way included having to change the order of additional dependencies in the custom linker options so my library came before the SDL one. But got there in the end- thanks again.
 
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