Look-Up Table Transform for Hardware Area Reduction

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Solution Overview

Problem

The implementation of fixed-function hardware logic for processors is hindered by the large area requirements of look-up tables (LUTs) needed to represent complex functions, especially when higher precision is demanded, leading to infeasible hardware sizes in space-constrained devices.

Innovation Solution

The method involves generating a single look-up table representing a function, applying a transform such as the Haar wavelet to divide it into multiple derived LUTs, and implementing these in fixed-function hardware logic along with an inverse transform unit, allowing for reduced hardware area while maintaining low latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single large look-up table is used to represent complex functions with high precision, then measurement precision is improved, but area of stationary object increases significantly

Engineering Contradiction:
Improvefunction precisionVSAvoidhardware area
Core Design Contradiction:
Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent divides a single large look-up table into multiple smaller derived look-up tables by applying a transform (e.g., Haar wavelet transform). Each derived LUT stores a portion of the function data, and their combined outputs reconstruct the original function with minimal error. This segmentation reduces the area required for each individual LUT while maintaining overall function precision.

Inventive Principle:
Principle #1Segmentation

2Area of stationary object

If multiple derived LUTs are implemented to reduce hardware area, then area of stationary object is reduced, but device complexity increases

Engineering Contradiction:
Improvehardware areaVSAvoidhardware complexity
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent introduces a transform unit as an intermediary component that processes inputs to select and combine outputs from multiple derived LUTs. This mediator enables the system to use smaller LUTs while reconstructing the original function, balancing area reduction against the added complexity of the transform logic.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If numerous instances of a function are implemented to satisfy performance metrics, then productivity is improved, but area of stationary object becomes very large

Engineering Contradiction:
ImprovethroughputVSAvoidhardware area
Core Design Contradiction:
ProductivityVSArea of stationary object

Solution Approach 1:

The patent creates a universal function implementation using multiple derived LUTs that can serve multiple function instances. By sharing the transformed LUT structure across numerous function instances, the system achieves high throughput while avoiding the area multiplication that would occur with identical separate implementations for each instance.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentUS20230028953A1Implementing functions in hardware
Publication Date: 2023.01.26 IMAGINATION TECH LTD
  • US20230028953A1 patent drawing
  • US20230028953A1 patent drawing
  • US20230028953A1 patent drawing

AI summary

Methods for implementing or synthesizing functions in hardware and fixed-function hardware include generating a look-up table, LUT, representing the function and then applying a transform to the LUT to transform the LUT into a plurality of derived LUTs. The transform may be applied recursively. A hardware design implementing each of the derived LUTs in fixed-function hardware logic, along with a logic unit that performs the inverse transform, is then created.