FloatSpscRingBuffer

High-performance non-blocking SPSC ring buffer specialized for Float.

Layout: a single Array[Long]. Each slot packs both the data and the occupancy/control signal into one 64-bit word:

• bits 32..63: tag (0 = empty, 1 = data, 2 = done)
• bits 0..31: Float.floatToRawIntBits(value) (only meaningful when tag == 1)

The packed slot itself is the FastFlow signal; one memory-ordered op per insert/remove, one cache line per slot. All Float values are representable (including 0.0f, NaN, +/-Inf); the non-zero tag guarantees a stored slot is never zero.

In-band "done" sentinel: producers can call offerDone() to insert an end-of-stream marker after the last data value. Consumers reading via pollPacked() receive EMPTY_PACKED for empty, DONE_PACKED for the sentinel, or a TAG_FULL | float bits value for data. This removes the need for a separate control queue alongside the data queue.

SPSC: one producer thread, one consumer thread.