Address Decoding Circuit Latency Reduction via Partitioning
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Solution Overview
Problem
In complex computing systems, such as FPGAs with larger address widths or more addressable target circuits, address decoding becomes a critical path and introduces additional latency, necessitating a solution to mitigate or eliminate this latency while maintaining high operating frequencies.
Innovation Solution
The method involves partitioning a range of encoded addresses into subsets, where high-frequency addresses are decoded in a single clock cycle and low-frequency addresses in multiple clock cycles, with a wait signal halting further transactions until high-priority addresses are decoded, using an address partitioning circuit and pipelining to optimize decoding operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If address decoding is performed in a single clock cycle, then transaction speed is improved, but complexity of the address decoding circuit increases
Solution Approach 1:
The address decoding circuit is segmented into multiple stages: a first address decoding circuit that decodes a first portion of the address, and a second address decoding circuit that decodes a second portion of the address. This segmentation allows the overall decoding process to be broken down into manageable parts that can operate in parallel or sequence, reducing the complexity of any single decoding stage while maintaining high transaction speed.
2Adaptability or versatility
If address decoding circuit complexity is increased to handle more target circuits, then addressable target circuits increase, but transactional latency increases
Solution Approach 1:
The patent introduces a hierarchical dimension to address decoding by organizing target circuits into groups and using a two-level decoding structure. The first address decoding circuit handles the primary address portion to identify a group of target circuits, while the second address decoding circuit handles the secondary address portion to identify the specific target within the group. This dimensional organization allows the system to address a large number of target circuits without proportionally increasing the latency of individual address decoding transactions.
3Measurement precision
If address decoding is performed sequentially for all addresses, then decoding accuracy is improved, but throughput decreases
Solution Approach 1:
The first address decoding circuit performs preliminary decoding of the first address portion to identify a group of target circuits before the second address decoding circuit processes the second address portion. This preliminary action allows the system to prepare and organize the decoding results in advance, ensuring decoding accuracy while enabling parallel or pipelined processing that maintains high throughput.
Data Source
AI summary
Techniques for reducing latency in address decoding are described. According to one approach, a method of operating an addressing circuit comprises partitioning range of encoded addresses into a first and second subset of encoded addresses, sending a first encoded address to a address decode circuit from a controller. In response to determining that the first encoded address is contained in the first subset, decoding the first encoded address in a first duration. In response to determining that the first encoded address is contained in the second subset, decoding the first encoded address in a second duration which is longer than the first duration and simultaneously sending a halt signal to the controller to stop sending subsequent encoded addresses for decoding for the entirety of the second duration.