# FC05 — queues, blocking and byte-copy semantics

The card is a deterministic FreeRTOS C experiment for RV32I/Hazard3. A queue
of length one exposes both wait lists: the receiver first blocks on an empty
queue, then the sender blocks while trying to append `M3` to a full queue.

The main proof is not a screenshot-only claim. The source buffer holding `M2`
is mutated after `xQueueSend()`, while the receiver later obtains the original
payload from queue storage. A bounded event log, public task state and a stable
digest connect the UML steps to GDB checkpoints.

```sh
make check
python3 /home/user/dev/workspace/stem/tools/card-layouts/tools/build_freertos_c_card.py .
python3 /home/user/dev/workspace/stem/tools/card-layouts/tools/render_card.py .
```

Generated HTML is in `web/index.html`; TeX is in `doc/generated/main.tex`.