CLARINET: A RISC-V Based Framework for Posit Arithmetic Empiricism

Abstract

CLARINET is an open-source, RISC-V based processor framework designed for the empirical validation of posit arithmetic as a potential replacement for the IEEE 754 floating-point standard. The framework incorporates 'Melodica,' a dedicated posit arithmetic core implementing unique parametric fused operations that utilize the high-precision quire data type. This system represents the first documented integration of the quire accumulation register within a RISC-V core, allowing researchers to seamlessly benchmark high-precision applications like linear algebra and computer vision kernels.

Report

Key Highlights

• Framework Identity: CLARINET is a general-purpose processor framework based on the RISC-V Instruction Set Architecture (ISA).
• Primary Goal: To facilitate the empirical validation and comparison of posit arithmetic against the established IEEE 754 floating-point standard.
• Unique Component: The framework includes the 'Melodica' posit arithmetic core.
• Novelty: CLARINET is the first documented integration of the specialized quire (used for long accumulations) data type within a RISC-V core environment.
• Accessibility: The framework is designed for the coexistence of both posit and floating-point number systems, allowing seamless experimentation.
• Availability: CLARINET and Melodica are open-source and actively under development.

Technical Details

• Architecture Base: The CLARINET processor is built upon the RISC-V ISA.
• Arithmetic Core: Melodica is the posit arithmetic core, specializing in implementing parametric fused operations.
• High-Precision Feature: The core uniquely supports the quire data type, which is critical for handling long accumulations with reduced rounding error.
• Validation Method: The platform's effectiveness was shown via an extensive application study benchmarking common linear algebra and computer vision kernels.
• Implementation Platform: The framework was emulated on a Xilinx FPGA to gather real-world utilization and timing data.

Implications

• Accelerating Posit Adoption: CLARINET provides the necessary infrastructure for researchers to move beyond theoretical models and rigorously test the claimed advantages of posit arithmetic (e.g., higher dynamic range, better accuracy, and superior performance-area trade-offs).
• Advancing RISC-V: By integrating novel arithmetic standards like posits and the quire accumulator, the framework expands the RISC-V ecosystem's capability into specialized high-performance and high-precision computing domains.
• Open Research: As an open-source framework, CLARINET lowers the barrier to entry for developing and testing applications that require high-precision computation, fostering community development around future arithmetic standards.
• Impact on Scientific Computing: This work offers a powerful, consolidated tool that could potentially influence the transition away from the current IEEE 754 standard in scientific and engineering fields where computational accuracy is paramount.