MIP: An OPM MI Disassembler

0.2.16

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Remarks:

Subproject MIP is currently under development, and is supposed to be available in a future release of the project.

Introduction

As a subproject of i5toolkit, MIP was launched in the January of 2011. Like what it is named, MIP is to disassemble an OPM program into corresponding OPM MI source, which can useful for:

• Alanyzing the program logics of the original program.
• Compiling a new program that behaves just the same as its original copy using MIP's cousin, MIC.
• Modifying existing program logics of the original program or adding new ones to it.

Content

• Overview of MIP
• Getting Start with MIP
• Techniques

Overview of MIP

The goal of subproject MIP is to implement a practical OPM MI disassembler along with documentations on techniques involved in the disassembling process. OPM MI is not only a set of MI instructions, it's also a programming language (simple, elegant, and powerful). I hope the documentations provided here would help you in understanding and mastering this programming language.

The name of the core CL command of MIP is 'MIP' which resides library I5TOOLKIT. The QShell command name of MIP's 'mip'.

The pre-requisite of applying MIP on an OPM program is that the target program contains observable information; in other words, it haven't been modified by operations such as CHGPGM RMVOBS(*ALL), or it's not a IBM supplied one.

Note that MIP isn't a tool for RPG or COBOL programmers. The output source code of MIP is in OPM IM language. So you need the basic knowledge in MI to read, modify, and compile the MI source back into an OPM program.

Getting Start with MIP

Assume that you have an OPM RPG program called ORPHEN whose lastest source isn't availble. To retrieve ORPHEN's MI source back into a source PF member, you might issue CL command MIP like the following:

MIP PGM(ORPHEN)
    SRCFILE(OLDTIME/MEMORY)
    SRCMBR(*PGM)

Techniques

Remarks:

For convenience, I refer to an OPM MI program simply as an MI program in the following docuemntation of this subproject.

First of all, all techniques we introduced here are based on an MI instruction, MATPG (Materialize Program). Prototype of MATPG's bound program interface, _MATPG, is defined in mih52.rpgleinc along with the receiver instruction template for this instruction, matpg_tmpl_t.

Todo:

link to mih52.rpgleinc

Documentation on techniques involved in the design of MIP are listed below:

• General Description of an OPM MI Program Template
• Analyzing the MI Instruction Stream of an OPM Program
• Analyzing Program Attributes
• Analyzing the ODV (ODT Directory Vector) Component and the OES (ODT Entry String) Component
• Analyzing the BOM Table Component
• Analyzing the Symbol Table Component
• Analyzing the OMT Component