k816 Language Support
VS Code extension for the K65 assembly language targeting the WDC 65C816 processor.
Provides syntax highlighting, language server integration, and debugging support
for the K816 toolchain.
Features
Editor
- Syntax highlighting for K65 assembly (
.k65 files)
- Document outline and breadcrumb navigation (functions, labels, data blocks)
- Code formatting (Format Document, Format on Save)
- Hover information with symbol details
- Live diagnostics (errors and warnings as you type)
- LSP server status in the status bar
Build
- F7 to build the project (
k816 build)
- Task provider with
build, clean, and run tasks (Terminal > Run Task)
- Custom tasks via
tasks.json for any k816 command (compile, link, fmt, etc.)
Debugging
- Launch and debug programs via the emulator's DAP interface
- Source-level breakpoints with automatic address resolution
- Disassembly view support (instruction pointer + disassemble request)
- Memory inspector support (read and write memory when adapter supports it)
- Inline debug values for registers and resolved symbol addresses/values
- Configurable emulator path and arguments
#k816_lookup_instruction: look up bundled 65816 mnemonic descriptions#k816_query_memory_map: query current linker memory-map usage from the
workspace language server state
Example prompts in Copilot chat or agent mode:
Use #k816_lookup_instruction for ADCUse #k816_query_memory_map with detail=runsUse #k816_query_memory_map for memory_name=MAIN
Prerequisites
- VS Code
1.109.0 or newer
- The
k816 binary installed and on your PATH (or set k816.server.path)
- For debugging: the emulator binary (or set
k816.debugger.path)
- For language model tools: GitHub Copilot chat/agent features enabled
Getting Started
- Install the extension (
.vsix or from the marketplace)
- Open a folder containing
.k65 source files
- The language server starts automatically
- Press F7 to build, or F5 to debug
Settings
Language Server
| Setting |
Default |
Description |
k816.server.path |
k816 |
Path to the k816 executable |
k816.server.args |
["lsp"] |
Arguments for the language server |
k816.server.env |
{} |
Extra environment variables |
k816.trace.server |
off |
Trace level: off, messages, verbose |
Debugger
| Setting |
Default |
Description |
k816.debugger.path |
emu |
Path to the emulator executable |
k816.debugger.args |
["--dap"] |
Arguments for the debug adapter |
k816.debugger.env |
{} |
Extra environment variables |
k816.debugger.inlineValues |
true |
Enable inline debug values while stopped |
k816.trace.debugger |
off |
DAP trace level: off, messages, verbose |
Commands
| Command |
Keybinding |
Description |
| K816: Build |
F7 |
Build the project |
| K816: Restart Language Server |
|
Restart the LSP server |
Debug Configuration
Add to .vscode/launch.json:
{
"type": "k816",
"request": "launch",
"name": "Debug K65 Program",
"program": "${workspaceFolder}/target/output.xex"
}
| Property |
Required |
Description |
program |
yes |
Path to the binary (.xex) to debug |
stopOnEntry |
no |
Pause on the first instruction (default: false) |
Troubleshooting
- Check the k816 LSP output channel for server logs
- Check the k816 DAP output channel for debugger communication (when tracing is enabled)
- If the server fails to start, verify
k816.server.path points to a valid executable
- Click the k816 status bar item to restart the language server
Development
cd editors/vscode-k816
npm install
npm run compile
Press F5 in VS Code to launch an Extension Development Host.
npm run package
Creates a local .vsix artifact.
License
0BSD
| |
