LorenzoStage

Header: modules/predictors/lorenzo/lorenzo_stage.h
Class: fz::LorenzoStage<T>
Category: Predictor (lossless)

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What it does

Plain integer Lorenzo predictor. Lossless, size-preserving.

• Forward (compression): compute per-element deltas from spatial neighbors.
• Inverse (decompression): prefix-sum to reconstruct original values.

Supports 1-D, 2-D, and 3-D layouts. Typically placed after a QuantizerStage in cuSZp-style pipelines (float → quant → Lorenzo → bitpack), where it operates on the quantization codes rather than raw floating-point data.

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Template parameter

Parameter	Constraint
T	Signed integer (see available instantiations below)

Available instantiations

Only these types are compiled and linked:

• LorenzoStage<int8_t>
• LorenzoStage<int16_t>
• LorenzoStage<int32_t>
• LorenzoStage<int64_t>

Using any other type will result in a linker error. Common choice: LorenzoStage<int32_t> (to match quantizer code width).

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Stage settings

No stage-specific setters. Spatial dimensions are supplied via Pipeline::setDims() or by calling stage->setDims() directly after addStage().

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Ports

Single input → single output; element type and size are unchanged.

Direction	Port	Type
Input	"output" (default)	T[n]
Output	"output"	T[n]

Connection from a quantizer upstream uses the "codes" port of the quantizer:

p.connect(lrz, quant, "codes");

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Dimension setup — critical ordering rule

Same rule as LorenzoQuantStage: call p.setDims() before addStage(), or call stage->setDims() directly after adding.

p.setDims(nx, ny, nz);
auto* lrz = p.addStage<LorenzoStage<int32_t>>();

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Typical pipeline (cuSZp-style)

p.setDims(nx);
auto* quant = p.addStage<QuantizerStage<float, int32_t>>();
auto* lrz   = p.addStage<LorenzoStage<int32_t>>();
auto* bpack = p.addStage<BitpackStage<uint32_t>>();
 
p.connect(lrz,   quant, "codes");
p.connect(bpack, lrz);
p.finalize();