Extract-Shift-Add Instruction for Single-Cycle Table Address Generation
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Solution Overview
Problem
Current processors require multiple execution cycles to calculate addresses for table lookups, which can slow down operations and increase bus accesses in digital signal processors (DSPs).
Innovation Solution
A method and system that utilize a single instruction, known as the extract-shift-add instruction, to extract bit field data from a register, shift it, and insert it into a second register with a table address portion to generate an address for an element within a table, allowing for address calculation in a single execution cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional multi-step address calculation methods are used, then address calculation can be performed, but the number of execution cycles increases and processor performance decreases
Solution Approach 1:
The patent combines multiple address calculation operations (bit field extraction, shifting, and addition) into a single integrated instruction called extract-shift-add (ESA). This merging of operations allows the processor to complete address calculation in one execution cycle instead of multiple separate cycles, directly resolving the contradiction between calculation capability and execution time.
Solution Approach 2:
The instruction pre-positions the bit field extraction, shifting, and addition operations to be executed simultaneously in a single cycle. By preparing all necessary components (source register, bit field parameters, destination register) before execution and designing the instruction to perform all operations in one step, the patent eliminates the sequential delays that would otherwise occur between these operations.
2Ease of operation
If multiple instructions are used for address calculation, then comprehensive address generation is achieved, but device complexity and instruction overhead increase
Solution Approach 1:
The patent merges bit field extraction, bit shifting, and arithmetic addition into a single extract-shift-add instruction. This consolidation reduces the number of instructions from multiple separate operations to one unified instruction, simplifying the operation sequence and reducing instruction overhead while maintaining full address calculation functionality.
Solution Approach 2:
The extract-shift-add instruction is designed as a universal instruction that can handle various address calculation scenarios (different bit fields, different shift amounts, different base addresses) through a single unified operation. This multi-functionality eliminates the need for multiple specialized instructions, reducing device complexity while maintaining ease of operation.
Data Source
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AI summary
In a particular embodiment, a method is disclosed that includes executing a single instruction to identify a location within a table stored at a memory. The single instruction is executable by a processor to extract bit field data from a first register and insert the bit field data into an index portion of a second register. The second register includes a table address portion and an index portion. The table address portion includes a table address identifying a memory location associated with a table. The table address and the bit field data combine to form an indexed address to an element within the table.