Atari XEX Memory Analyzer

A VS Code extension that visualizes and analyzes the memory layout of Atari 8-bit .xex executables produced by llvm-mos (and, in a later phase, cc65/ca65).

Open a .xex file and it renders an interactive memory map: where each segment loads in the 64 KB address space, which OS/hardware/ROM regions it touches, how much RAM is used vs. free, and warnings for overlaps, gaps, and loads over reserved memory.

Features

Memory map & analysis

• XEX parser — segments, RUNAD/INITAD vectors, truncation detection.
• Linear memory strip — 0000–FFFF canvas with Atari region bands (zero page, stack, OS vars, DOS, program RAM, cart/BASIC, hardware, OS ROM), loaded sections colored by kind, and a data-symbol lane naming every buffer in place. Scroll to zoom, drag to pan, double-click to reset.
• Analysis — loaded/runtime bytes, free RAM, load extent, overlap & gap detection, and "loads over reserved region" warnings.
• Extra views — zero-page grid, RAM budget bar, largest-contributors, segment/section/data-buffer tables, warnings, legend.
• Markdown report export (Atari XEX: Export Memory Report).

Map enrichment (auto-discovers a sibling .map / .lbl)

• llvm-mos LLD maps — section split (.text/.rodata/.data/.bss/.zp*) with symbol-level detail.
• cc65/ca65 ld65 maps — segment list + exports, with named segments (PLAYERMISSILE, MYFONT, DISPLAYLIST, FRAMEBUFFER, …) and VICE .lbl symbols. Symbol sizes inferred from gaps (cc65 maps carry no sizes).
• Both cross-checked against the file image for a runtime-only (bss) flag.

Graphics / video memory

• Identified from linker symbols and segment names (high confidence on location): PMG, character sets / fonts, display list, sprite data, frame buffers — role from the symbol/segment name (always shown). cc65's named segments make this especially direct.
• Display-list decoding — walks a loaded ANTIC display list's LMS instructions to locate screen memory with evidence (not name guessing).
• Code-scan heuristics for PMBASE/SDLST/SAVMSC when no map is present (clearly labeled low-confidence).

Source linking (Phase 3.5)

• Each region/buffer links to its source declaration — type, array dimensions, comment, and a click-to-open jump to file:line. Prefers DWARF from the ELF when present; otherwise scans the source tree (config atariXex.sourceRoot, else auto-detected).

Pixel viewer (Phase 3.6)

• Click a graphics region, a data-buffer row, or a buffer on the strip's symbol lane to render its bytes as an image: 1bpp sprites/PMG, 8×8 character sets/fonts, 2bpp multicolor, or hex. Renders only bytes that are actually in the file — runtime-built (.bss) buffers are reported as such, never faked.

Opens automatically as a custom read-only editor for *.xex, or via the Atari XEX: Analyze Memory Layout command.

Develop

npm install
npm run build        # or: npm run watch
npm run typecheck
npm run test:unit    # vitest

Press F5 in VS Code (or code --extensionDevelopmentPath=.) to launch the extension development host, then open a .xex file.

Architecture

• src/core/ — pure, no vscode import, unit-tested: XEX parser, Atari region model, analysis engine, wire model.
• src/host/ — custom editor provider, CSP webview HTML, messaging.
• src/webview/ — separately-bundled Canvas/SVG visualization (zero runtime deps).