Search Unit for Finding First Two Bit Values in Vector
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Solution Overview
Problem
Conventional mechanisms for finding free registers in a register bank within an out-of-order execution engine are inefficient due to the use of many logic gates, resulting in significant delays and increased complexity.
Innovation Solution
A search unit is integrated into an integrated circuit to concurrently find the first two instances of a predetermined bit value within a vector, utilizing a modified carry-lookahead adder tree structure that operates on triplets of bits, reducing the need for serial traversals and minimizing logic gates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mechanisms use many logic gates to find free registers, then the register availability tracking is achieved, but the propagation delay increases significantly
Solution Approach 1:
The input vector is divided into multiple segments or groups of bits. The search unit processes each segment independently and concurrently, finding the first two predetermined bit values in parallel across segments. This segmentation reduces the propagation delay by avoiding sequential traversal through the entire vector, while still ensuring reliable identification of free registers through systematic segment-by-segment search.
2Measurement precision
If conventional mechanisms use serial traversal to find bit instances, then the search is thorough, but the logic complexity increases
Solution Approach 1:
The search unit transitions from serial one-dimensional traversal to parallel multi-dimensional processing by simultaneously examining multiple bit positions across different segments. This dimensional change allows the circuit to maintain thorough search coverage while reducing logic complexity through concurrent operations and optimized gate structures that evaluate multiple paths in parallel rather than sequentially.
Data Source
AI summary
An integrated circuit includes a search unit configured to access an input vector including a number of bits, and to find a first and a second instance of a predetermined bit value such as a logic zero or a logic one, for example. The search unit may be further configured to generate an output that includes an indication of a bit position of the first instance of the predetermined bit value within the input vector, and an indication of a bit position of the second instance of the predetermined bit value within the input vector.