lens

One ROM Lens

One ROM Lens (onerom-lens) is a browser tool that runs the One ROM PIO/DMA serving algorithms and visualises the resulting waveforms — a cycle-exact logic analyser for the emulated ROM.

It compiles to WebAssembly and runs the real firmware serving code via onerom-fw-emulator; the browser front-end (web/logic-analyzer.js) drives it through a small C ABI (onerom_*) exposed with Emscripten's ccall/cwrap.

Like the emulator, the ROM image, board and pin geometry are baked in at build time from a CONFIG + BOARD, so each build targets one hardware variant and ROM image. To look at a different chip, rebuild with a different config/board.

Prerequisites

• The Emscripten SDK on PATH (emcc, emar). Install with ci/install-emscripten.sh, or on macOS brew install emscripten.
• The Rust wasm target: rustup target add wasm32-unknown-emscripten.
• python3 (for the local web server).

Build and run

From the repo root:

rust/lens/serve.sh [CONFIG] [BOARD] [PORT]

For example, a random-content 2316 on a Fire 24 rev A:

rust/lens/serve.sh onerom-config/test/24-random-23xx.json fire-24-a

Then open http://localhost:8000/ in a browser. With no arguments the script defaults to that config on fire-24-a, port 8000.

Building the wasm directly

serve.sh is a thin wrapper over a normal cargo build:

cd rust
CONFIG=onerom-config/test/24-random-23xx.json BOARD=fire-24-a \
    cargo build -p onerom-lens --target wasm32-unknown-emscripten

This emits target/wasm32-unknown-emscripten/debug/onerom-lens.js (the Emscripten loader, a OneRomLens() factory) and onerom_lens.wasm. Serve those alongside the files in web/.

The wasm build is exercised in CI by ci/build-lens.sh (an 8-bit 2364 and a 16-bit 27C400). The underlying serving correctness is regression-tested by the emulator suite (ci/test-emu.sh / pio-tester), which shares this crate's engine.