A new SCENARIO_FUZZ branch in tb_ddc_cosim.v accepts +hex / +csv / +tag
plusargs so an external runner can pick stimulus and output paths per
iteration. The three path registers are widened to 4 kbit each so long
temp-directory paths (e.g. /private/var/folders/...) do not overflow
the MSB and emerge truncated — a real failure mode caught while writing
this runner.
test_ddc_cosim_fuzz.py is a pytest-driven fuzz harness:
- Generates a random plausible radar scene per seed (1-4 targets with
random range/velocity/RCS/phase, random noise level 0.5-6.0 LSB
stddev) via radar_scene.generate_adc_samples, fully deterministic.
- Compiles tb_ddc_cosim.v once per session (module-scope fixture),
then runs vvp per seed.
- Asserts sample-count bounds consistent with 4x CIC decimation,
signed-18 range on every baseband I/Q word, and non-zero output
(catches silent pipeline stalls).
- Ships with two tiers: test_ddc_fuzz_fast (8 seeds, default CI) and
test_ddc_fuzz_full (100 seeds, opt-in via -m slow) matching the
audit ask.
Registers the "slow" marker in pyproject.toml for the 100-seed opt-in.
Jason
51740fd6f5