Mail Archives: djgpp-announce/2013/08/18/14:54:30
This is a port of Lua 5.2.2 to MSDOS/DJGPP.
Lua is a powerful, light-weight programming language designed for extending
applications. Lua is also frequently used as a general-purpose, stand-alone
language. Lua is free software.
To compile this port you will need to check out the libc sources from the
CVS repository and compile your own c library. This is required because
gcc 4.5.X and later create .eh_frame sections in object files by default.
When building DXE modules from object files containing .eh_frame sections,
dxe3gen generates code that calls the __deregister_frame_info and
__register_frame_info functions. The dxe3gen program has been improved
to detect this case and automatically resolve these both symbols. This
will be the case if the used programing language has no exception handling
support like C. If C++ is used to code the .so library (DXE module), then
the symbols will not be resolved and the .so library must be linked with
libgcc.a that will provide working versions of both versions.
Please note that even if gcc generates exception handling frames and dxe3gen
emits those calls, the exception handling capability of DXE modules has _not_
changed and improved in anyway.
Please also note that you do not need to worry about all this if you use
gcc 4.4.5 or a previous version to compile the sources. Those compilers
do not create .eh_frame sections by default so that all these difficulties
do not appear and you can use your stock djdev204 libc.a.
DJGPP specific changes.
=======================
- All DXE modules generated or used with this port must use the .so extension
and not the usual .dxe one. The .dxe extension is not honored by the port.
- The port will honor the new platform "djgpp". This means, to compile the
port you must pass djgpp as argument to the Makefile in the top srcdir.
- Instead of using the hard coded template string "/tmp/lua_XXXXXX", this
port will create the names of its temporary files using the template string
composed by "luXXXXXX" and a prefix pointing to a directory. The directory
is determined by testing, in sequence, the directories defined by the values
of environment variables TMPDIR, TEMP and TMP. The first variable that is
found to point to an existing directory will be used. If none of these
variables specify a valid directory, P_tmpdir will be used.
- The port will search at "/dir/env/DJDIR/share/lua/5.2/" for the .lua or .lc
files to be loaded at run time. This path can be overwritten by setting the
LUA_PATH environment variable. To learn how the environment variable must
look like, please read the docs.
- The port will search at "/dir/env/DJDIR/lib/lua/5.2/" for the .so libraries
to be loaded at run time. This path can be overwritten by setting the
LUA_CPATH environment variable. To learn how the environment variable must
look like, please read the docs.
- The .so libraries are loaded at run time using DJGPP's dlopen, dlclose and
dlsym functions. The .so libraries are created using DJGPP's dxe3gen utility.
This means that you are restricted to the limitations that are inherent to
the DXE3 concept. To understand what is possible and how to create DXE
modules read the dxe3gen documentation.
- The .so extension for dynamically loaded libraries is mandatory. No other
extension will be honored; especially not the .dxe extension that is
supposed to be the dxe3gen default extension.
- All functions inside a .so library must conform to the C-function API
defined by Lua if they shall be accessed by a .lua or .lc program. That
means that every C function gets as only argument the Lua state. This is
a pointer to a lua_State structure. This structure contains a stack from
which the function arguments are pulled. The results that the function
shall return to the caller must be pushed back on the stack. As return
value the function must always return the number of objects pushed on the
stack. C-functions that do not conform to this API cannot be accessed by
a Lua program and should not be exported. For more information about this
read the Lua docs.
- .so libraries created by dxe3gen shall not be linked with the Lua library.
This means you shold not pass "liblua.a" as argument to dxe3gen. The
loading of the .so library at run time is done by the ll_load() and ll_sym()
functions in loadlib.c. This is the place where the table with the symbols
that shall be exported to the .so library is defined. You must expand this
table according to the symbols that are reported as unresolved by dxe3gen.
Currently this table contains the names of all push and pop functions that
the Lua library provides and that are intended to be used to manipulate
the Lua stack from inside of a C-function. Apart from those function names
I have also added printf and puts to the list. Those are the only function
names that I have added from libc. If you use other functions from libc
you must either link your library against libc and see if this is enough to
resolve all unresolved symbols or not link against libc at all and add all
unresolved symbols to the table, in the same way as this issue has been
handled for the Lua library. Here you are alone and you must try out what
the best solution would be.
If your .so library contains unresolved symbols that are not defined by the
table used by ll_load you will get at run time an error message like this:
function_name: unresolved symbol in DXE module.
where function_name stands for the function used in the .so library that
does not appear in the symbol table. In this case you must expand the
table by adding an entry like this:
DXE_EXPORT(function_name)
and recompile the sources. I have found no way to adapt the symbol table
at run time.
- There are 2 ways to load a .so library at run time.
1) You can use the low-level Lua function called package.loadlib. In this
case you must pass as arguments to the function the absolute path to
the .so library and the exact name of the function to be loaded.
E.g.:
package.loadlib("/dev/env/DJDIR/lib/lua/5.2/libmylib.so", "_my_function")
Please note that you have to put an underscore before the function name.
No search along any paths are done. If the loading fails then the Lua
program will fail.
2) You can use the Lua function called "require". In this case you must
pass the name of the library without path and extension. The library
will be searched along the LUA_PATH and LUA_CPATH paths or its hard
coded defaults if they are not set.
I have added 4 files to demonstrate how this works with this port.
The files are stored in the /djgpp directory. You can run these DJGPP
specific tests passing test_djgpp as argument to the makefile.
- To compile the port you will need to install the latest readline port.
This is rdln62b.zip. I have not tested any previous version and I will
not support any of those.
- The port has been test with the test suite available as:
http://www.lua.org/tests/5.2/lua-5.2.2-tests.tar.gz
After having installed lua, run the test suite by cd-ing into lua-5.2.2-tests
directory and starting the lua test script with the command:
lua -e"_U=true" all.lua
No check will fail. The final output should look like this:
test done on 18/08/2013, at 18:05:05
Lua 5.2
final OK !!!
cleaning all!!!!
---- total memory: 27.7K, max memory: 1.6M ----
total time: 4.78
>>> closing state <<<
Because the dlfcn/dxe3 functionality is required to build this port, it can
only be compiled using djdev204. There will be no version compiled with
djdev203.
As usual, all djgpp specific files (diffs, README files, etc.) are located in
the /djgpp directory.
For further information about Lua please read the docs.
Please note that I have only ported this package. I do not use Lua at all so
I will not be able to answer questions that are not related to porting issues.
----------------------------------------------------------------------------
The port has been compiled using a freshly compiled version of the CVS
repository and consists of the usual three packages that can be downloaded
from ftp.delorie.com and mirrors as (time stamp 2013-08-18):
Lua 5.2.2 binary, library and man format documentation:
ftp://ftp.delorie.com/pub/djgpp/beta/v2tk/lua522b.zip
Lua 5.2.2 html format documentation:
ftp://ftp.delorie.com/pub/djgpp/beta/v2tk/lua522d.zip
Lua 5.2.2 source:
ftp://ftp.delorie.com/pub/djgpp/beta/v2tk/lua522s.zip
Send Lua specific bug reports to <lua-l AT lists DOT lua DOT org>.
Send suggestions and bug reports concerning the DJGPP port
to comp.os.msdos.djgpp or <djgpp AT delorie DOT com>.
Enjoy.
Guerrero, Juan Manuel <juan DOT guerrero AT gmx DOT de>
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