Browse Prior Art Database

High Level Language Decision Table Decompiler

IP.com Disclosure Number: IPCOM000089481D
Original Publication Date: 1977-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Larson, LE: AUTHOR

Abstract

This is an APL process for converting high level language program implementations to decision tables by converting the high level language input to a specially encoded ASSEMBLER language format. To simplify the explanation of the process, the description is particularized to the case of PL/1.

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High Level Language Decision Table Decompiler

This is an APL process for converting high level language program implementations to decision tables by converting the high level language input to a specially encoded ASSEMBLER language format. To simplify the explanation of the process, the description is particularized to the case of PL/1.

The program to be decompiled is written in the high level language (PL/1) and is placed into an appropriate file. The name of the file is given to the processor, and the processor reads the file, creating an input list of the file. The input list is then converted to a compressed text by the processor for its later use.

The processor reads the converted input list, and creates from it a specially encoded assembler language program. `IF' statements are converted to assembler conditional operations followed by an appropriate branch instruction. A similar conversion occurs for the `ELSE' statement. The simple `DO-END' group is converted to code strings with the `DO' and `END' removed. However, a non-simple `DO' group is retained intact. The statements `GOTO' and `RETURN' are converted to unconditional branch statements.

The internal text is traced, and an internal decision table is created.

The stubs of the internal decision table is converted to the external format, and presented as output.

The processor is so constructed that the decompilation process can be applied to APL as well. The process can be extended to other programming ...