Mike

I'm trying to use the Bloodshed IDE (which compiles with minGW 3.4.2) to whip up a couple of the externals provided as examples in the SDK. I can get everything imported okay, and it compiles with no errors. However, I put it in my externals folder, and it doesn't work. I type in the object name and get "invalid external [name], undefined main". I would assume this refers to the main function of the ext, which I did not change. Given that it compiled with no errors, I find this rather befuddling.

Anyone else have a similar problem with this or any other dev env? Anyone had success using minGW? I've spent several hours on this and it's getting quite frustrating. I know there are some lite versions of MSVS available, but I would really rather use Bloodshed.

I'm trying to use the Bloodshed IDE (which compiles with minGW 3.4.2) to whip up a couple of the externals provided as examples in the SDK.  I can get everything imported okay, and it compiles with no errors.  However, I put it in my externals folder, and it doesn't work.  I type in the object name and get "invalid external [name], undefined main".  I would assume this refers to the main function of the ext, which I did not change.  Given that it compiled with no errors, I find this rather befuddling.
   Anyone else have a similar problem with this or any other dev env?  Anyone had success using minGW?  I've spent several hours on this and it's getting quite frustrating.  I know there are some lite versions of MSVS available, but I would really rather use Bloodshed.

mingw-external-problem

If you searchthe jitter-dev forum for cygwin development, you may get

some ideas there. Otherwise, I have no idea.

If you searchthe jitter-dev forum for cygwin development, you may get
some ideas there.  Otherwise, I have no idea.

On Jun 1, 2006, at 5:25 PM, Mike Sayre wrote:

> I'm trying to use the Bloodshed IDE (which compiles with minGW 

> 3.4.2) to whip up a couple of the externals provided as examples in 

> the SDK. I can get everything imported okay, and it compiles with 

> no errors. However, I put it in my externals folder, and it 

> doesn't work. I type in the object name and get "invalid external 

> [name], undefined main". I would assume this refers to the main 

> function of the ext, which I did not change. Given that it 

> compiled with no errors, I find this rather befuddling.

It might be possible that it's not exporting a main function (needs 

to happen, and is defined in the .def file provided as input to the 

linker). Or possibly the file is being compiled with C++ and the main 

function is somehow decorated, though the former sounds more likely 

to me. Make sure that the GCC command being executed for linking is 

something like the following (with the appropriate .def file):

gcc -shared -mno-cygwin -o minimum.mxe minimum.o minimum.def -L../../ 

> Anyone else have a similar problem with this or any other dev 

I was able to have success with cygwin/mingw/gcc from the command 

line and the basic steps are documented in the Cygwin_gcc_HowTo.rtf 

distributed with the windows SDK. Compare the GCC commands BloodShed 

generates with those from this document, and perhaps it will shed 

Sounds promising, but you might be he first to wrestle with building 

a Max object with this IDE. Please share your findings so that others 

who wish to use bloodshed won't have to suffer as you have.

>
>    I'm trying to use the Bloodshed IDE (which compiles with minGW  
> 3.4.2) to whip up a couple of the externals provided as examples in  
> the SDK.  I can get everything imported okay, and it compiles with  
> no errors.  However, I put it in my externals folder, and it  
> doesn't work.  I type in the object name and get "invalid external  
> [name], undefined main".  I would assume this refers to the main  
> function of the ext, which I did not change.  Given that it  
> compiled with no errors, I find this rather befuddling.

It might be possible that it's not exporting a main function (needs  
to happen, and is defined in the .def file provided as input to the  
linker). Or possibly the file is being compiled with C++ and the main  
function is somehow decorated, though the former sounds more likely  
to me. Make sure that the GCC command being executed for linking is  
something like the following (with the appropriate .def file):

gcc -shared -mno-cygwin -o minimum.mxe minimum.o minimum.def -L../../ 
c74support/max-includes -lMaxAPI

>    Anyone else have a similar problem with this or any other dev  
> env?  Anyone had success using minGW?

I was able to have success with cygwin/mingw/gcc from the command  
line and the basic steps are documented in the Cygwin_gcc_HowTo.rtf  
distributed with the windows SDK. Compare the GCC commands BloodShed  
generates with those from this document, and perhaps it will shed  
some light.

Sounds promising, but you might be he first to wrestle with building  
a Max object with this IDE. Please share your findings so that others  
who wish to use bloodshed won't have to suffer as you have.

On Thu, 1 Jun 2006, Joshua Kit Clayton wrote:

> decorated, though the former sounds more likely to me. Make sure that the GCC 

> command being executed for linking is something like the following (with the 

> gcc -shared -mno-cygwin -o minimum.mxe minimum.o minimum.def 

> -L../../c74support/max-includes -lMaxAPI

I used cygwin to compile rtcmix~ for windows which draws upon a mixed 

C/C+ library. Depending on what functions/objects you call, you may not 

be able to use the -mno-cygwin flag easily... and then you have tto drag

around the cygwin1.dll lib. I'm looking into using just the mingw

compiler, or possibly the free MS compiler instead.

http://www.delorie.com/howto/cygwin/mno-cygwin-howto.html

I haven't read through it closely yet, but it looks like it contains some

> decorated, though the former sounds more likely to me. Make sure that the GCC 
> command being executed for linking is something like the following (with the 
> appropriate .def file):
>
> gcc -shared -mno-cygwin -o minimum.mxe minimum.o minimum.def 
> -L../../c74support/max-includes -lMaxAPI

I used cygwin to compile rtcmix~ for windows which draws upon a mixed 
C/C+ library.  Depending on what functions/objects you call, you may not 
be able to use the -mno-cygwin flag easily... and then you have tto drag
around the cygwin1.dll lib.  I'm looking into using just the mingw
compiler, or possibly the free MS compiler instead.

         http://www.delorie.com/howto/cygwin/mno-cygwin-howto.html

I haven't read through it closely yet, but it looks like it contains some
good information.

Thanks for the good suggestions. I will try them this afternoon after I get out of class (yay for summer school!) and get back to you with my findings. Some preliminary things I have found already:

I can't seem to find a way through the IDE to set the struct alignment to 2 bytes. It seems to already be set to this - at least when I open the project in MSVS. I must confess I'm a little fuzzy on the topic in the first place. Is this a compiler flag? Linker flag? I can put it in manually, I suppose, but I don't know the syntax or where it goes using minGW.

The other major complication was finding the right libraries. In order to compile with minGW, I had to download the objective C libraries, which I found here:

http://wiki.codeblocks.org/index.php?title=MinGW_installatio

Everyone,
   Thanks for the good suggestions.  I will try them this afternoon  after I get out of class (yay for summer school!) and get back to you with my findings.  Some preliminary things I have found already:
   I can't seem to find a way through the IDE to set the struct alignment to 2 bytes.  It seems to already be set to this - at least when I open the project in MSVS.  I must confess I'm a little fuzzy on the topic in the first place.  Is this a compiler flag?  Linker flag?  I can put it in manually, I suppose, but I don't know the syntax or where it goes using minGW.
   The other major complication was finding the right libraries.  In order to compile with minGW, I had to download the objective C libraries, which I found here:

 http://wiki.codeblocks.org/index.php?title=MinGW_installatio n

for struct alignment you might want to try

the final pack pragma is to reset the struct packing to the default.

The default struct packing should be whatever is most efficient to 

make sure that all 32 bit types are 32 bit aligned and 64 bit types 

There seem to be drastic performance penalties (or errors) for most 

#pragma pack(2)
typedef struct _twoByteAlignedStruct {
	short foo;
	char fooc;
	short bar;
	float foo;
} twoByteAlignedStruct;

The default struct packing should be whatever is most efficient to  
make sure that all 32 bit types are 32 bit aligned and 64 bit types  
are 64 bit aligned.
There seem to be drastic performance penalties (or errors) for most  
architectures when this isn't the case.

On Jun 2, 2006, at 7:15 AM, Mike Sayre wrote:

> I can't seem to find a way through the IDE to set the struct 

> alignment to 2 bytes. It seems to already be set to this - at 

> least when I open the project in MSVS. I must confess I'm a little 

> fuzzy on the topic in the first place. Is this a compiler flag? 

> Linker flag? I can put it in manually, I suppose, but I don't know 

> the syntax or where it goes using minGW.

This as Mark specified can be set using compiler #pragma directives. 

We now have this in place for the standard MaxMSP headers where it's 

necessary, so this requirement is no longer necessary to setup for 

> The other major complication was finding the right libraries. 

> In order to compile with minGW, I had to download the objective C 

Are you writing your object in Obj C? Great language, but I don't 

know that many people using it outside the Macintosh community. This 

might also be introducing some complications if you're not 

appropriately decorating things which should have C style exports.

I would suggest you approach the problem systematically:

1. download latest gcc, and mingw libraries together through cygwin's 

setup utility as described in the Cygwin_gcc_HowTo.rtf

2. try to get the minimum object SDK example file compiling from the 

3. try to resolve any issues with BloodShed and the minimum project

4. try to resolve any problems with your own extern in BloodShed

>    I can't seem to find a way through the IDE to set the struct  
> alignment to 2 bytes.  It seems to already be set to this - at  
> least when I open the project in MSVS.  I must confess I'm a little  
> fuzzy on the topic in the first place.  Is this a compiler flag?   
> Linker flag?  I can put it in manually, I suppose, but I don't know  
> the syntax or where it goes using minGW.

This as Mark specified can be set using compiler #pragma directives.  
We now have this in place for the standard MaxMSP headers where it's  
necessary, so this requirement is no longer necessary to setup for  
your project.

>    The other major complication was finding the right libraries.   
> In order to compile with minGW, I had to download the objective C  
> libraries, which I found here:
>
>   http://wiki.codeblocks.org/index.php?title=MinGW_installatio n

Are you writing your object in Obj C? Great language, but I don't  
know that many people using it outside the Macintosh community. This  
might also be introducing some complications if you're not  
appropriately decorating things which should have C style exports.

1. download latest gcc, and mingw libraries together through cygwin's  
setup utility as described in the Cygwin_gcc_HowTo.rtf

2. try to get the minimum object SDK example file compiling from the  
command line and loading in MaxMSP

I followed your suggestions and first compiled the min external with cygwin - worked like a charm. Then I tried moving it into Bloodshed and got frustrated by an idiotic problem for a while. When Bloodshed builds, it writes its own makefiles and .def files. I looked at the def file it was generating, and sure enough, it wasn't exporting anything at all. When I tried to change the makefile to make it use my def file and told Bloodshed to use a custom def file, it overwrote my makefile AND my def file! I couldn't get it to use the .def file supplied in the SDK. 

However, I dug around on the documentation; you are NOT supposed to add the def file to your project - it won't hurt anything if you do, so long as you don't try to include it in the linking process (I did that, and then I got duplicate definition errors between it and the generated def file)and there's a linker flag you can specify, "--def defFile.def". And then it works. By default, Bloodshed includes quite a few funky other flags for the compiler and linker that seemed unncessary, so I just deleted them.

So, it took a crapload of extra work, but it now works. Hopefully people will be able to use this info - always great to use free tools! I would upload the files, but the forum is being stubborn. 

Thanks to everyone who helped - now I can get started on my custom externals. I'm sure that I'll be back with lots of questions...

HAH!  Success!
   I followed your suggestions and first compiled the min external with cygwin - worked like a charm.  Then I tried moving it into Bloodshed and got frustrated by an idiotic problem for a while.  When Bloodshed builds, it writes its own makefiles and .def files.  I looked at the def file it was generating, and sure enough, it wasn't exporting anything at all.  When I tried to change the makefile to make it use my def file and told Bloodshed to use a custom def file, it overwrote my makefile AND my def file!  I couldn't get it to use the .def file supplied in the SDK.  
   However, I dug around on the documentation; you are NOT supposed to add the def file to your project - it won't hurt anything if you do, so long as you don't try to include it in the linking process (I did that, and then I got duplicate definition errors between it and the generated def file)and there's a linker flag you can specify, "--def defFile.def".   And then it works.  By default, Bloodshed includes quite a few funky other flags for the compiler and linker that seemed unncessary, so I just deleted them.
   So, it took a crapload of extra work, but it now works.  Hopefully people will be able to use this info - always great to use free tools!  I would upload the files, but the forum is being stubborn. 
   Thanks to everyone who helped - now I can get started on my custom externals.  I'm sure that I'll be back with lots of questions...

minGW, external problem