RZEStage

Header: modules/coders/rze/rze_stage.h
Class: fz::RZEStage — no template parameters
Category: Coder (lossless)

Common instantiation:

auto* rze = p.addStage<fz::RZEStage>();

---

What it does

Recursive Zero-byte Elimination. Operates on raw byte streams (typically BitshuffleStage output). Each chunk is processed in up to 4 recursive levels:

• Level 1 (ZE): compact non-zero bytes; emit an N/8-byte zero bitmap.
• Levels 2–4 (RE): compact non-repeated bytes of the previous bitmap.

Because bit-shuffled scientific data can have many zero byte-planes, RZE can compress those planes very aggressively.

---

Stage settings

rze->setChunkSize(16384);   // bytes; must be a multiple of 4096 (default 16384)
rze->setLevels(4);          // recursion depth 1–4 (default 4)

---

Alignment requirement

Requires input to be a multiple of chunk_size bytes. The pipeline pads automatically when BitshuffleStage upstream uses a matching block_size.

---

Typical pipeline

auto* bshuf = p.addStage<BitshuffleStage>();
auto* rze   = p.addStage<RZEStage>();
 
rze->setChunkSize(16384);
rze->setLevels(4);
 
p.connect(rze, bshuf);
p.finalize();

---

Stream layout (forward output)

[uint32_t: original byte count]
[uint32_t: num_chunks]
[uint32_t x num_chunks: per-chunk compressed sizes (high bit set -> chunk stored raw)]
[compressed chunk data ...]