# `SSCMEx.Tick`

Same-clock helpers for `SSCMEx.Image.timestamp`.

`SSCMEx.Image.timestamp` is set inside the NIF from
`clock_gettime(CLOCK_MONOTONIC)` in nanoseconds. Erlang's
`System.monotonic_time/1` is also CLOCK_MONOTONIC-based on Linux but
uses a different epoch (VM-start vs system-boot), so subtracting one
from the other gives nonsense. Use `now/0` here to read the same
clock that stamps frames, then arithmetic on `image.timestamp` is
meaningful.

## Example — measuring chip-to-Elixir frame dwell

    {:ok, image} = SSCMEx.Camera.retrieve_frame(cam, 0)
    dwell_ns = SSCMEx.Tick.now() - image.timestamp
    dwell_ms = div(dwell_ns, 1_000_000)

# `now`

```elixir
@spec now() :: integer()
```

Returns the current value of `CLOCK_MONOTONIC` in nanoseconds —
the same clock and unit that `SSCMEx.Image.timestamp` is stamped
with at frame capture time.

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*Consult [api-reference.md](api-reference.md) for complete listing*