Two-Stage Decompression Circuit for LZMA Dependency Bottlenecks

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Solution Overview

Problem

In LZMA decompression, the use of data associated with the distance-length pair reduces decompression efficiency as it requires previous literals for decompressing the next literal, leading to slower processing.

Innovation Solution

A decompression circuit and method that separates the decompression process into two units, where the first unit performs initial decompression without using data from the distance-length pair, allowing the second unit to handle the distance-length pair independently, thereby enhancing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If data associated with the distance-length pair is used when decompressing the next literal, then decompression accuracy is improved, but decompression speed deteriorates

Engineering Contradiction:

Improvedecompression accuracyVSAvoiddecompression speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The decompression process is segmented into two independent stages: first decompressing the distance-length pair to obtain reference literals, then decompressing the next literal using those reference literals. This segmentation allows parallel processing and eliminates waiting dependencies, resolving the contradiction between accuracy (requiring reference literals) and speed (requiring independent processing).

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The distance-length pair is decompressed in advance before the next literal is processed. By performing this preliminary action, the reference literals are ready beforehand, allowing the next literal decompression to proceed independently without waiting, thus improving decompression speed while maintaining accuracy.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If the decompression process waits for data from the LZ77 unit, then decompression accuracy is improved, but overall decompression time increases

Engineering Contradiction:

Improvedecompression accuracyVSAvoidoverall decompression time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The decompression circuit is divided into two independent units: a first decompression unit for the distance-length pair and a second decompression unit for the next literal. This segmentation eliminates the sequential dependency where the second unit had to wait for the first unit, reducing overall decompression time while maintaining accuracy through proper data flow design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Both decompression units operate continuously and independently without idle waiting periods. The first unit processes the distance-length pair while the second unit simultaneously processes the next literal using pre-available reference data, ensuring continuous useful action and minimizing total decompression time.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS8854235B1Decompression circuit and associated compression method and decompression method

Publication Date: 2014.10.07 MEDIATEK INC

AI summary

A decompression circuit for decompressing data includes a first decompression unit and a second decompression unit. The data sequentially includes a compressed first string, a compressed distance-length pair and a compressed second string. The first decompression unit performs a first decompression on the data to obtain a first string, a distance-length pair and a second string. The second decompression unit receives and decompresses the first string, the distance-length pair and the second string. The first decompression unit does not involve data associated with the distance-length pair when decompression the second string.