ASTOC Overview

ASTOC has been designed as an expert tool but also as an optimized component for the most efficient conversion approach. The targets were:

• Convert assembler to C with maximum precision
• Extract knowledge for two purposes: code documentation and programmer transition
• Grant absolute conversion control to the programmer(s) in charge
• Automate whatever can be automated

This is the strategy that embeds ASTOC conversion tools:

PREPARE A PROJECT

After initial project planning, the work area is defined and all targeted assembler modules are collected. Data structures and interfaces are mapped, macro conversion strategies are selected and based on these findings the ASTOC toolset is configured.

CONVERT

A proper preparation which requires a rather small period of time makes the subsequent conversion almost self-running. The three-step ASTOC approach is the following:

1. Process
ASTOC reads and analyzes single assembler source files. Files are checked for correctness, completeness and integrity. Extensive reporting is performed on missing or incorrect parts, in order to make this phase as short as possible. Global and local macros are processed individually according to the selected rules. Finally, ASTOC generates pre-conversion pseudo-code.

2. Optimize
During iterative optimizer runs, ASTOC reorganizes code blocks, eliminates control flow problems and maps to C constructs. Program simulation and register tracking aid in correct re-engineering to produce structured code.

3. Rewrite
Finally, ASTOC outputs distinct ANSI C-language source files with meaningful code and data names and a clean organization. On top of this, ASTOC includes the selected amount of embedded documentation:

• To ease the transition to C for assembler programmers, the original assembler code can be listed as comments.
• If this amount of information is not required, only the original comments will be included, producing more compact C code.

After conversion, some manual code adjustments may be required to incorporate the generated code into the global project.

COMPILE and TEST

Since ASTOC may be applied to individual modules at a time, they can each be compiled and tested immediately.

This strategy has been found to be an efficient yet flexible general-purpose approach to the translation of mainframe assembler. Using advanced tools to speed-up the most labor-intensive phases, almost every assembler conversion project can be completed in considerably less time with far better results.