VX/FORTRAN - OpenVMS FORTRAN to ANSI FORTRAN

Overview

VX/Fortran is a powerful automated migration tool that translates OpenVMS Fortran to ANSI-compliant Fortran (Intel Fortran) for execution on x86 Linux and Windows. It extends Fortran Partner (FPT) with VMS-specific features, standards adherence, and performance optimizations.

VX/Fortran is used by aerospace, defense, and high-tech industries to ensure complete, error-free Fortran migration, preserving decades of software investment without requiring manual code modifications.

Key Features

• 100% Automated Migration – Converts VMS / OpenVMS Fortran to Intel Fortran, preserving functionality.

• Zero Code Freeze – Continue development on VMS while migrating to Linux/Windows.

• Advanced Static Analysis – Detects syntax, logical, and performance issues before migration.

• Embedded SQL Conversion – Automatically converts Pro*Fortran SQL to external C functions.

• Seamless ISAM Support – VX/RMS replaces obsolete ISAM handling with modern Fortran I/O.

• Code Optimization – Performs loop unrolling, inline expansion, and memory access optimizations.

• Comprehensive Testing Tools – Supports record/replay execution, trace logs, and QA compliance.

• Security & Obfuscation – Can protect source code while ensuring it remains compilable.

VX/Fortran Migration Process

VX/Fortran automates the entire migration workflow, ensuring a smooth transition from OpenVMS Fortran to modern platforms.
‍

Step	Process
Source Code Analysis	Identifies VMS-specific extensions, RMS file dependencies, and *ProFortran SQL statements**.
Transpile to Modern Fortran	Automatically converts VMS extensions to ANSI-standard Fortran.
Compile & Optimize	Optimizes for Intel Fortran, expanding loops and removing legacy constraints.
Execute & Validate	Runs automated test cases to verify identical execution behavior.

Code Migration Examples

File Handling - VMS vs. Migrated Code

VX/Fortran automatically translates VMS file-handling commands to modern Fortran.
‍

VMS Fortran Code	Migrated ANSI Fortran Code
`OPEN (UNIT=report_lun, FILE='LOGS:MONITOR.LOG', STATUS='UNKNOWN')`	`OPEN (UNIT=report_lun, FILE=vxrms_translate_file_name ('LOGS:MONITOR.LOG'), STATUS='UNKNOWN')`
`OPEN(UNIT=INDXUFLUN, ACCESS='KEYED', FILE='INDXUF.DAT', STATUS='OLD')`	`CALL VXRMS_OPEN('UNIT=', INDXUFLUN, 'ACCESS=', 'KEYED', 'FILE=', 'INDXUF.DAT', 'STATUS=', 'OLD')`

Inline Function Expansion for Performance

VX/Fortran expands subroutines inline to reduce function call overhead.

Before (VMS Fortran)

REAL*4 FUNCTION INTERP1(INPUT, BP, FUNTAB)
REAL*4 INPUT
REAL*4 BP(*)
REAL*4 FUNTAB(*)
I = 1
DO WHILE (BP(I) .LT. INPUT)
  I = I + 1
ENDDO
INTERP1 = FUNTAB(I-1) + (FUNTAB(I) - FUNTAB(I-1))
* (INPUT - BP(I-1)) / (BP(I) - BP(I-1))
RETURN
END

After (Optimized Fortran)

DO WHILE (TYREVBP(I) .LT. TYRESPEED)
  I = I + 1
ENDDO
FR = TYREFRICT(I-1) + (TYREFRICT(I) - TYREFRICT(I-1))
* (TYRESPEED - TYREVBP(I-1)) / (TYREVBP(I) - TYREVBP(I-1))

🔹 Eliminates function calls

🔹 Reduces memory access latency

🔹 Speeds up execution time by up to 40%

Automated Fortran Code Quality Analysis

VX/Fortran automatically detects and fixes errors, improving code quality and maintainability.

Diagnostic	Count	Impact
Missing subroutine declarations	12	Prevents compilation errors
Inconsistent argument types	8	Fixes potential runtime crashes
Unsafe integer-to-real conversion	15	Prevents loss of precision

Why Choose VX/Fortran?

✔ 100% Automated Migration – No Manual Remediation Required

✔ Zero Code Freeze – Develop & Migrate in Parallel

✔ Optimized Execution – Faster Than Legacy VMS Fortran

✔ Seamless RMS & SQL Handling – Works Out-of-the-Box

✔ Bug-Free Code – Automated Testing & Debugging

🔹 VX/Fortran is the fastest and most reliable way to modernize your VMS Fortran applications for Linux & Windows.