CMS-2 Language Support for Visual Studio Code

Language Server Protocol (LSP) implementation for CMS-2 (Compiler Monitor System 2), the US Navy's standard programming language for tactical combat systems.

About CMS-2

CMS-2 was developed in 1968-1969 by Computer Sciences Corporation with Intermetrics for the US Navy. It remains in active use on:

Aegis Combat System - cruisers, destroyers
Submarine combat control systems
Naval Tactical Data System (NTDS)
Aircraft carrier battle management

Target computers include the AN/UYK-7 and AN/UYK-43, with the language still powering critical naval defence infrastructure worldwide.

Features

Syntax highlighting for CMS-2Y constructs
Code completion for keywords, variables, procedures, functions
Hover information with type details
Go to definition for symbols
Find references across the document
Document outline showing programme structure
Support for all CMS-2 constructs:
- SYS-DD/SYS-PROC blocks
- VRBL (variable) declarations
- TABLE/FIELD definitions
- PROCEDURE/FUNCTION blocks
- TYPE declarations with status values

Installation

Install the extension from the VS Code Marketplace
Ensure Python 3.8+ is installed and available in PATH
Open any .cms2, .cm2, or .cms file

File Extensions

Extension	Description
`.cms2`	CMS-2 source file
`.cm2`	CMS-2 source file (alternate)
`.cms`	CMS-2 source file (short)

Language Overview

CMS-2 uses unique syntax elements:

''This is a comment in CMS-2''

CMODE D $  ''Set constant mode to decimal''

TESTDD SYS-DD $
    VRBL COUNTER I 16 S $       ''16-bit signed integer''
    VRBL POSITION A 32 S 16 $   ''32-bit fixed-point, 16 fractional bits''
    VRBL FLAG B $               ''Boolean''
    VRBL MESSAGE H 20 $         ''20-character string''

    TYPE MODE 'OFF', 'ON', 'AUTO' $  ''Status type''

    TABLE DATA_BUFFER V MEDIUM 100 $
        FIELD VALUE A 16 S 8 $
        FIELD STATUS I 8 U $
    END-TABLE DATA_BUFFER $
END-SYS-DD TESTDD $

TESTSP SYS-PROC $
    PROCEDURE PROCESS INPUT X OUTPUT Y $
        SET Y TO X * 2 $
        RETURN $
    END-PROC PROCESS $
END-SYS-PROC TESTSP $

Key Syntax Elements

Statement terminator: $ (dollar sign)
Comments: ''comment text'' (double apostrophes)
Type specifiers:
- I bits S/U - Integer (signed/unsigned)
- A bits S/U frac - Fixed-point with fractional bits
- F - Floating-point
- B - Boolean
- H length - Character string
Scope modifiers: (EXTDEF), (EXTREF), (LOCREF), (TRANSREF)
Packing modes: NONE, MEDIUM, DENSE

Documentation Sources

This extension was developed using official US Navy documentation:

CMS-2Y Programmer's Reference Manual (M-5049), Rev 16, October 1986
- Fleet Combat Direction Systems Support Activity, San Diego
CMS-2 Compiler and Monitor System (AN/UYK-7), August 1975
- UNIVAC
Steps Toward a Revised CMS-2, NPS Thesis, 1973
- Naval Postgraduate School

Configuration

Setting	Description	Default
`cms2.pythonPath`	Path to Python interpreter	`python`
`cms2.serverPath`	Path to LSP server script	(bundled)
`cms2.trace.server`	Trace level for debugging	`off`

Requirements

Visual Studio Code 1.75.0 or later
Python 3.8 or later

Known Limitations

The parser handles common CMS-2Y constructs but may not cover all extensions
Some legacy CMS-2M (16-bit) specific features may not be fully supported
Real-time executive features require additional context

Licence

Licensed under the Apache Licence, Version 2.0. See LICENSE for details.

Contributing

Contributions are welcome! Please open an issue or pull request on GitHub.

Acknowledgements

Fleet Combat Direction Systems Support Activity (FCDSSA), San Diego
Naval Postgraduate School
US Navy tactical systems documentation archives

CMS-2 Navy Tactical Language

Zane Hambly