= Compiling and linking user-defined code = 
[[TracNav(doc/userint/toc)]]

You can use your user-interface within a PALM-run by carrying out the following steps:\\\\
   1. Copy the appropriate default (empty) user-interface files {{{user_***.f90}}} to the folder that has been defined in the configuration file  by variable {{{user_source_path}}}. The default for this folder is {{{$HOME/palm/current_version/JOBS/$run_identifier/USER_CODE}}}, so in case the run identifier is {{{example}}}:
{{{
   cd ~/palm/current_version
   mkdir -p JOBS/example/USER_CODE
   cp trunk/SOURCE/user_***.f90  JOBS/example/USER_CODE
}}}
      '''Attention: do not change the names of the user-interface files! '''

   2. Modify the interface routines according to your needs.\\

   3. Start a PALM run by entering
{{{
   palmrun -d example ...
}}}
      The files {{{user_***.f90}}} will be automatically compiled as part of this run, before PALM is executed, and will replace {{{PALM}}}‘s respective default user-interface routines. The compiled binaries are put into a folder named {{{SOURCES_FOR_RUN_$configuration_identifier_$run_identifier}}}, where they replace the default binaries that have been created via {{{palmbuild}}}. The {{{SOURCES_FOR_RUN}}} folder is created in the directory defined by variable {{{fast_io_catalog}}} in the configuration file. It is newly created for each manual call of {{{palmrun}}}. \\\\

Since the run identifier is part of the user-interface's SOURCE path, you can use different interfaces for different runs at the same time. Just store the respective interface-files in sub-folders {{{JOB/abcd/USER_CODE}}}, {{{JOBS/cdef/USER_CODE}}}, etc. and call {{{palmrun}}} with option "{{{-d abcd}}}", "{{{-d cdef}}}", etc. \\\\
If you like to add additional routines which are not part of the default user-interface (see the [wiki:doc/app/userint/int list of available interface routines]), you can a) append this routines to the default user-interface file {{{user_additional_routines.f90}}} or b) create new files in your user-interface folder. These files must have names different from the default {{{PALM}}} source code files. In case of b), you must also copy the default {{{Makefile}}} into the user-interface folder, e.g.:
{{{
   cp trunk/SOURCE/Makefile  JOBS/example/USER_CODE
}}}
Edit the {{{Makefile}}} and add your new files and possible dependencies, following the standard "make"-rules.\\\\

== How to avoid re-compilation of user-interfaces

It is important to know, that in general '''the modified user-interface files cannot be pre-compiled''' with {{{palmbuild}}}. This would not make sense because your user-interface may differ among your PALM runs, so you would need different {{{MAKE_DEPOSITORIES}}} depending on the run-identifier (option {{{-d}}}). Therefore, {{{palmrun}}} compiles the user-interface each time you call the script. Strictly speaking, {{{palmrun}}} internally calls {{{palmbuild}}} with special options, and {{{palmbuild}}} then compiles the user-interface and generates the {{{SOURCES_FOR_RUN}}} folder (see above).

In case you carry out a large number of test runs and don't want the user-interface to be compiled each time again (because it may take a lot of time, and you didn't change it), you can suppress compilation by adding {{{palmrun}}} option {{{-V}}}. Then, {{{palmrun}}}/{{{palmbuild}}} tries to re-use the compiled interface from the last call of {{{palmrun}}} with same configuration identifier and run identifier (given by options {{{-h}}} and {{{-d}}}), by re-using the respective {{{SOURCES_FOR_RUN}}} folder that has been generated by the previous run. Automatically generated calls of {{{palmrun}}} (restart runs in job chains) use the same method, so they do not need to compile the user-interface again. \\\\

For debugging user-defined code, see section [../../intdbg Debugging].