Apt's sourcecode is available under GPL.
To build Apt, here are a few instructions, and things you'll need:
A Linux Machine
Well, at least this tutorial follows the assumption that you're on a Linux machine. If somebody wants to write one about building Apt on Windows, go ahead…
I used a Ubuntu Intrepid 8.10 Desktop running as a Virtual Machine under VMWare. A command-line system would do fine, though.
Core Palm OS SDK from the ACCESS website
Download the latest from http://accessdevnet.com:
Register, Login, Downloads, Garnet OS, ACCESS SDK's, Core Garnet OS SDK, Garnet OS SDK (68K) R3 PRC tools Generic UNIX
Version is 5.3.
Install into /opt/palmdev so that you have a /opt/palmdev/sdk-5r3/include/core directory, for example.
Palm SDK from Palm Developer Network
This contains device specifics and can be obtained from http://pdnet.palm.com
Register, Login, Developers, Develop for Palm OS, Download SDK, Download SDK for Palm Products on Palm OS Platform, Palm SDK Header Files (.ZIP 444KB)
Unzip somewhere and move the files in "incs" to /opt/palmdev/sdk-5r3/include so you get a /opt/palmdev/sdk-5r3/include/68k directory, for example.
pilrc: the Resource Compiler
This puts all the widgets, like buttons and menus, in the .prc.
Get it from from http://sourceforge.net/projects/pilrc/,
sudo apt-get install pilrc
This is the gcc compiler, linker, etc.
Use the 68k compiler even if you code for devices with ARM processor - the 68k is the universally compatible Palm OS compiler.
Apt-get in recent Ubuntus fails to get this.
Install in that order.
Apt's Source Code
This should come in at some point, right?
Get it from this very site, on the Download section.
Put it somewhere like /home/me/apt or wherever you prefer.
Run make on that directory and let's start solving errors.
Solving some familiar make problems:
Can't find m68k-palmos-gcc:
Check your prc-tools install.
unrecognized option "-palmos5r3"
Ignore this, as long as the compiler finds the libraries, this is probably not needed.
Can't find some include directory:
Check where you uncompressed your SDK's, try to match the files that gcc is looking for with your directories.
Watch out for upper/lowercase directory names: I had to capitalize a few names on the SDK directories and files to get it to compile.
If you have to make changes, make them on the SDK tree structure and file/dir names, let's leave Apt's makefile constant.
"ignoring unknown pragma: ;"
Safe to ignore. If it bothers you, you can
a) delete the #pragma mark …" lines from the SDK's source files.
b) add option -Wno-unknown-pragmas right after -Wall on Apt's makefile.
complains about "\" lost at the end of lines
sudo apt-get install tofrodos
dos2unix -f *.h
… on all the SDK directories where the files are. It's not as bad as it seems, there are only 4 or 5 of them. I bet some Unix bash geek can get it all done in one command and teach us.
If all goes well, you should have a new Apt.prc on your disk. Check the file's timestamp to see if it matches the current time.
These help you test your build on a virtual Palm OS device.
Get them from http://pdnet.palm.com.
They only run on Windows.
Register, Login, Developers, Develop for Palm OS, Download SDK, Download SDK for Palm Products on Palm OS Platform, select the Simulator(s) you want and download.
Just unzip and run the exe.
Right-click on the simulator screen for options like "install—>database" which allows you to put Apt into the device.