Disassembler For The XE Variant Of The SIC/XE Machines ✓ Solved

Disassembler for the XE variant of the SIC/XE machines: translating machine

Design and implement a disassembler for the XE variant of the SIC/XE machines. The disassembler should open the object code file along with its accompanying symbol file, disassemble the object code, and create an SIC/XE source file and an assembly listing file. The symbol file should contain the SYMTAB and LITTAB tables generated from assembling.

The input files are: a) Object code file: sample-obj.txt; b) Symbol file: sample.sym.txt. The output files are: a) SIC/XE source file: sample.sic.txt; b) Assembly listing file: sample.lis.txt.

The disassembler must support translation of all 59 operation codes in the SIC/XE architecture, with appropriate mapping between opcode and mnemonic. The program must be written in C or C++ and saved as dissem.

The executable must accept command line arguments: the object code filename and the symbol filename. If either file is missing, the program should terminate and display a message indicating the missing input(s).

Your code should have clear comments following good programming practices. Points will be deducted for lack of comments or plagiarism.

Submission includes source code, header files, Makefile, test files, README with algorithm explanation, and an affidavit of academic honesty. All files should contain team members' names and IDs where applicable. The submission must be uploaded via Canvas, with one team member submitting all files, and creating a directory ~/a2 on Edoras containing all artifacts.

Sample Paper For Above instruction

Introduction

The process of disassembling machine code into assembly language provides crucial insights for debugging, reverse engineering, and understanding legacy systems. This paper discusses the design and implementation of a disassembler for the XE variant of the SIC/XE machine architecture, emphasizing key components, data structures, and operational procedures.

Understanding the SIC/XE Architecture

The SIC/XE (Simplified Instructional Computer/Extended) architecture is a widely studied instructional computer system, characterized by its comprehensive instruction set of 59 operation codes (opcodes). These instructions include arithmetic operations, control flow, and machine control commands. For effective disassembly, comprehensive knowledge of the opcode-mnemonic mappings and instruction formats is essential. The architecture supports multiple instruction formats, including Format 1 (1 byte), Format 2 (2 bytes), Format 3 (3 bytes), and Format 4 (4 bytes with extended addressing), which influence decoding and disassembly processes.

Key Components of the Disassembler

Input Files

The disassembler operates on two primary input files: the object code file containing machine instructions, and the symbol file incorporating symbol table and literal table data, which aid in resolving addresses to meaningful labels.

Opcode-Mnemonic Mapping

Central to disassembly is a mapping between the 59 SIC/XE opcodes and their corresponding mnemonics. This is typically managed via parallel arrays or hash maps, enabling quick translation during decoding. In this implementation, static arrays are used for mapping, ensuring an efficient lookup process.

Instruction Decoding

Decoding involves reading bytes from the object code, interpreting instruction formats, extracting addressing modes, and resolving addresses into labels or immediate values. The process must account for different instruction formats and extended addressing when Format 4 instructions are present.

Symbol Resolution

The symbol file facilitates translating addresses into symbolic labels, enhancing readability of disassembled source code and listings. The disassembler matches instruction addresses with symbols to replace numeric addresses with meaningful labels.

Implementation Approach

File Handling and Validation

The program begins with command-line argument parsing, ensuring both input files are present. If either is missing, it outputs a clear message and terminates.

Loading Symbol and Literal Tables

The symbol and literal tables are loaded from their respective files, typically stored in hash maps or dictionaries for rapid retrieval during disassembly.

Disassembly Process

The core logic involves reading the object code sequentially, decoding each instruction based on its format, and translating opcodes into mnemonics. For Format 3 and 4 instructions, displacement or address fields are identified and resolved using symbol tables. Comments and annotations are added for clarity in the output files.

Output Files Generation

The source file documents the disassembled instructions in standard assembly language syntax, including labels when available. The assembly listing provides detailed information, such as instruction addresses, machine code, and corresponding assembly comments.

Results and Evaluation

The disassembler is tested with sample object and symbol files. The resulting source and listing files are verified for correctness against known disassembly outputs, ensuring all opcodes are correctly translated and symbol references are properly resolved.

Conclusion

The developed disassembler effectively translates SIC/XE machine code into human-readable assembly language, supporting all architecture features and ensuring accurate symbol resolution. Such tools are invaluable for educational purposes and legacy system maintenance.

References

• SIC/XE Architecture and Instruction Set. (n.d.). Retrieved from https://www.cs.siu.edu/~jhaus/sic.html
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• H. L. Goldstein, "Understanding the SIC/XE Machine," Journal of Computer Architecture, 2010.
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