Assembly and C/C++ source code interpretation

I am currently working on a Java program that will be used to control a specific model of legacy digital circuit tester. To create this program, I have mainly relied on capturing network traffic between the current controller software and the equipment. I have recently obtained the complete source code for the firmware/software that runs internally on the equipment. This code is executed by a 486 processor contained within the equipment. I am in need of somebody with a large amount of experience in both assembly and C/C++ to assist me in extracting some specific information from this source code. The source code I'm trying to understand was mostly written in the mid 1980's and seems like complete gibberish to me. The information I'm looking for has to do with an "identification byte" that is used to identify the type of packet being sent from the computer to the equipment. The company that developed this software manually defined individual packet types for every type of command that can be sent across the network. I have located where the packets are defined and have some ideas where the ID bytes are also defined, but I haven't been able to get any useful information out of the source (mainly assembly). I believe that the specific hex values of the ID bytes are created using a macro -- one that I don't understand. My goal for this job is to have a list of all the packet-types and their corresponding ID bytes. I am attaching a few Wireshark captures that will show the IP traffic, including the ID bytes. Most of the commands from the Solaris box to the equipment start with "3......." (as Wireshark displays non-printable characters as '.'). The right-most byte in that command is the ID byte. The capture files also have commands that start with "1......." or "2.......", but "3......." seems to be the main one. I will be willing to provide some of the source code upon request provided that you have a sufficient feedback from other jobs. This source code is obviously proprietary, and while I have the rights to have and use it, I do not wish to make it more available than necessary.