17 year old 'Carmageddon' debugging symbols file dumped

In the Carmageddon Splat Pack folder, there is a file called ‘DETHRSC.SYM’, last modified 13th November 1997.

It has sat there, un-noticed and un-loved for the last 17 years, ignored by the internet. Having made a remake of the Carmageddon engine, and being generally curious about random binary files, I tried to figure out the file format. Immediately by looking at it in a hex editor, it was obviously a debugging symbol file, the question was which type of symbol file? Of course, there are many symbol files with a .sym extension, and after some trial and error, it turned out to be a Watcom symbol file. I grabbed a copy of OpenWatcom and fired up the debugger, wd. It could read the symbols, but I never found any Carmageddon executable that matched up with it. It seems likely it was left there by mistake from a debug build.

Using wd to look at the symbols 1 by 1 in a little DOS window quickly becomes tiring, so then I wanted to dump the symbols out. For that, I needed the source code for the Watcom tools, and a working Open Watcom development environment.

…Fast forward a while getting the environment up and finding where the code for handling symbol files lives…

In the Watcom world, symbol file support is provided by various DIPs. To use a DIP dll requires the calling program to implement various client-side methods to allow the DIP to alloc memory etc, and then to provide callback functions for the DIP to call when walking the symbol list. It’s all pretty complex, but luckily there are a couple of utilities which illustrate generally how it should be done. I based jsonsymdump off dipdump (which is advertised as dumping symbol files to text format, but crashes on DETHRSRC.SYM). I did the minimal amount of work in C required to generate a valid json file, then wrote a node.js script to take that json file and generate some semi-valid-ish c files.

• Browsable symbol output here: http://bit.ly/1FM53Gj


• More details here: http://bit.ly/1FM55y1

submitted by jeff-1amstudios to gamedev

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