B-Prolog Port to EPOC

Installation

There are two versions of B-Prolog available:

The professional version which has garbage collection built-in.
The free version which does not.

There are some other minor differences for which refer to the main documentation.

Each one has its own installation file associated with it:

Bpfree.sis: The installation file for the free version.
BPProf.sis: The installation file for the professional version.

If you are reading this for the first time then you are probably using the free version which is, fairly obviously, in Bpfree.sis.

There is an additional "sis" file which can be used for installing the Constrained Graphics library which is compatible with either version (i.e. you do not have to use a different version of bpcg.sis if you upgrade to the professional version. See Constrained Grahics Library, below.

Double clicking on the appropriate BP*.sis file on a Windows machine with PsiWin installed will do all the hard work for you. Or you can copy it onto a Psion machine and, so long as you have the add/remove control installed it will take over and do the rest of the installation for you.

The final installation will look like this:

ESTLIB.dll and the required opx files will also be installed in the System\Libs and System\opx directories of your chosen drive.

Starting Up

Simply select the B-Prolog "tree icon" from the extras bar to get the following requestor:

Or, if you have the Constrained Graphics library installed:

See the B-Prolog documentation for explanations of the numerical parameters. The "Save as default" check box simply creates/over-writes the BProlog.ini file. This file contains saved values of the other entries in the requestor and so saves you having to correct the defaults every time you start it up.

B-Prolog in Action

Here is a screen shot of a pointless session with B-Prolog, just to show

It works!
My prolog programming style leaves something to be desired.

It also demonstrates that B-Prolog under EPOC doesn't exit immediately that a halt is encountered. This is to allow you to see the output from queries which might otherwise be lost when the console is shut down.

Trouble Shooting

If B-Prolog doesn't work try the settings shown below:

These are the minimum sizes for each of the memory areas I could successfully start-up with. If B-Prolog starts okay with these settings gradually increase them to meet your requirements.

These settings require a little over 1Mb for B-Prolog to run. If you can't manage to free that much memory then it is probably not worth running prolog on your system anyway.

Constrained Graphics Library

You can install cg.out on any drive independently of the main B-Prolog installation. If the B-Prolog loader can't find it you will not be asked whther you want to load it or not.

It requires considerably more program memory to run the Connstrained Graphics library and for this reason I haven't really tested it on Epoc.

Differences Between the EPOC Port and other Ports

The java interface has not been tested and is not included in the current release.
The system/1 predicate does nothing useful - suggestions/votes for what it should do in EPOC are welcome.
EPOC doesn't really have environment variables in the way that other operating systems do. The BPDIR is hard-coded as ...
I've added a cputimer/1 predicate which is like cputime/1 but returns a floating point number. This is required on my Series 5 as the standard cputime/1 tends to wrap around when I am timing longer runs.
The line-editing interface is based on code supplied by Duncan Booth from his Python port with some inspiration from Keith Walker and his Curses port. The keys are not the same as those described in the B-Prolog docs (yet). The keys are:

Ctrl-C
Interrupts query
Up/Down Arrow
Previous/Next saved query
Left/Right Arrow
Left/Right one character
Ctrl-Left/Right Arrow
Left/Right one word

To Do
- Look into improving memory allocation at start-up.
- Any suggestions?
Contact

You can contact me at timwentford@hotmail.com