VX/PASCAL - OpenVMS PASCAL to ANSI C++

Overview

VX/PASCAL is a highly automated transpiler that converts OpenVMS Pascal to beautiful ANSI-compliant C++ for execution on x86 Intel Linux and Windows. Unlike generic Pascal compilers, VX/PASCAL fully supports VMS-specific extensions, CDD data structures, RMS file handling, and VMS stack operations ensuing 100% compatibility with the original Pascal application.

VX/PASCAL is designed for continuous integration, meaning no code freeze is required during migration. The tool can process millions of lines of Pascal code with minimal human intervention, maintaining near-identical source structure and ensuring correctness without manual modifications.

Key Features

• 100% Automated Translation – Converts VMS Pascal to beautiful maintainable ANSI C++

• Zero Code Freeze – Continue developing in VMS Pascal while migrating incrementally

• Supports All VMS Extensions – Including stack argument tracking (PRESENT/NOT PRESENT)

• Integrated with VX/CDD – Retains Common Data Dictionary (CDD) structure

• Optimized String Handling – Converts Pascal string logic to efficient C++ equivalents

• Seamless RMS Integration – Index-sequential, relative, and direct access files fully supported

• Identical Execution & Debugging – “Bug-for-Bug” compatible with OpenVMS Pascal

VX/PASCAL Migration Process

VX/PASCAL automates the entire migration process, ensuring seamless transition from OpenVMS Pascal to C++.

Step	Process
Source Code Analysis	Scans Pascal source files for VMS-specific constructs, CDD references, and complex data types.
Transpile to C++	Automatically converts VMS Pascal to readable and maintainable C++, preserving original logic and structure.
Compile & Link	Uses GNU C++ (G++) or Clang to generate optimized binary executables.
Execute & Validate	Runs automated test cases to verify identical behavior between VMS Pascal and translated C++.

VX/PASCAL Code Translation Example

VMS Pascal Source Code

PROGRAM Example;
VAR
  A, B, C: INTEGER;
BEGIN
  A := 5;
  B := 10;
  C := A + B;
  WRITELN('Sum: ', C);
END.

Translated C++ Code

#include <iostream>

int main() {
    int A = 5, B = 10, C;
    C = A + B;
    std::cout << "Sum: " << C << std::endl;
    return 0;
}

VX/PASCAL ensures that translated C++ code is as close as possible to the original Pascal syntax, making it highly readable and maintainable.

Advanced Features & Optimization

1. Continuous Integration Workflow

VX/PASCAL allows simultaneous development and migration:

• No need to freeze development on VMS Pascal

• Source code remains synchronized between Pascal and C++

• Automated build process using MMS/Makefile conversions

2. String Handling & Code Formatting

VX/PASCAL optimizes VMS Pascal string logic for efficient C++ translation.

Pascal String Operation	Translated C++ Equivalent
`A := Me + "You" + Them;`	`A = Me + "You" + Them;`
Uses `STR$CONCAT` and `STR$COPY`	Optimized using C++ operator overloading

3. VMS Stack Emulation

VX/PASCAL ensures correct handling of VMS stack argument tracking (PRESENT/NOT PRESENT), which Linux does not natively support.

Example:

IF 5 > va_count THEN not(present);

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🔹 In Linux, this would result in stack corruption.

🔹 VX/PASCAL automatically corrects for Linux function argument handling.

VMS / OpenVMS Pascal RMS Support

VX/PASCAL fully supports RMS file operations on Linux & Windows using VX/RT and VX/RMS.

✅ Indexed, Relative, Sequential, Block file support

✅ Supports Keyed Access, RFA Access, and Record Locking

✅ Faster I/O Performance than native VMS RMS

VX/RMS maintains balanced B+ trees for faster retrieval speeds, reducing lookup times in large datasets.

VX/PASCAL Configuration Options

VX/PASCAL provides 500+ customizable options, including:

• VMS API Mapping

• Pascal to C++ Variable Naming Conventions

• VMS Logical Name Translation

• VMS POSIX Error Code Mapping

• Custom Code Formatting (Braces, Indentation, Line Breaks)

• Automatic Starlet Inheritance Handling

These options enable precise customization of the transpiled C++ output.

Conclusion

VX/PASCAL eliminates the challenges of migrating VMS Pascal to modern platforms, ensuring seamless execution on x86 Linux and Windows.

Why Choose VX/PASCAL?

✔ 100% Automated Transpilation – No Manual Code Changes Required

✔ Bug-for-Bug Compatibility – Identical Execution to VMS Pascal

✔ Zero Code Freeze – Continuous Development While Migrating

✔ Seamless RMS & CDD Integration

✔ Optimized String Handling & Code Readability

✔ Proven Success – 3M+ Lines Translated in < 6 Months

🔹 VX/PASCAL is the only solution that ensures complete, automated, and maintainable migration of OpenVMS Pascal to modern C++.

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