Jamie Bullock wrote:

Dear list,

I am thinking of writing a few PD externals, and so decided to try the HOW-TO tutorial at http://iem.kug.ac.at/pd/externals-HOWTO/node1.html.

I am using gcc 3.3.3. m_pd.h is version 0.37 and is in /usr/include.

The problem is that if I simply copy and paste the helloworld code into a text editor and try to compile with something like:

gcc helloworld_pd.c -o helloworld.pd_linux -l/usr/include

It fails with the wollowing output:

/usr/lib/gcc-lib/i386-redhat-linux/3.3.3/../../../crt1.o(.text+0x18): In function _start': : undefined reference tomain'

Here gcc is looking to compile a regular executable, when you really want it to build a shared library.

/tmp/ccWU3J7M.o(.text+0xf): In function helloworld_bang': : undefined reference topost'

This and the following errors all relate to gcc not being able to find the pd header files, the first of which is m_pd.h.

/tmp/ccWU3J7M.o(.text+0x28): In function helloworld_new': : undefined reference topd_new' /tmp/ccWU3J7M.o(.text+0x53): In function helloworld_setup': : undefined reference togensym' /tmp/ccWU3J7M.o(.text+0x5c): In function helloworld_setup': : undefined reference toclass_new' /tmp/ccWU3J7M.o(.text+0x77): In function helloworld_setup': : undefined reference toclass_addbang' collect2: ld returned 1 exit status

I apologise in advance if this question has already been answered - I couldn't find anything in the mail archives...

Previous posts have alluded to the absence of this vital information from the HOW-TO...

Any help would be appreciated.

Assuming you have the source for pd, check out the makefile in pd/extra/pique for an example of how to do it properly on all platforms. In particular note the need for -export_dynamic and -shared to indicate that you want to build a shared library, as well as -I../../src to give the path to m_pd.h. The easiest thing is usually to copy such a makefile and modify the file names and paths to suit your setup, then type 'make' to build your external.

Martin