PERCIVAL: Open-Source Posit RISC-V Core with Quire Capability

by   David Mallasén, et al.

The posit representation for real numbers is an alternative to the ubiquitous IEEE 754 floating-point standard. In this work, we present PERCIVAL, an application-level posit capable RISC-V core based on CVA6 that can execute all posit instructions, including the quire fused operations. This solves the obstacle encountered by previous works, which only included partial posit support or which had to emulate posits in software, thus limiting the scope or the scalability of their applications. In addition, Xposit, a RISC-V extension for posit instructions is incorporated into LLVM. Therefore, PERCIVAL is the first work that integrates the complete posit instruction set in hardware. These elements allow for the native execution of posit instructions as well as the standard floating-point ones, further permitting the comparison of these representations. FPGA and ASIC synthesis show the hardware cost of implementing 32-bit posits and highlight the significant overhead of including a quire accumulator. However, results comparing posits and IEEE floats show that the quire enables a more accurate execution of dot products. In general matrix multiplications, the accuracy error is reduced up to 4 orders of magnitude when compared with single-precision floats. Furthermore, performance comparisons show that these accuracy improvements do not hinder their execution, as posits run as fast as single-precision floats and exhibit better timing than double-precision floats, thus potentially providing an alternative representation.


Big-PERCIVAL: Exploring the Native Use of 64-Bit Posit Arithmetic in Scientific Computing

The accuracy requirements in many scientific computing workloads result ...

Using the pyMIC Offload Module in PyFR

PyFR is an open-source high-order accurate computational fluid dynamics ...

PERI: A Posit Enabled RISC-V Core

Owing to the failure of Dennard's scaling the last decade has seen a ste...

Design and implementation of an out-of-order execution engine of floating-point arithmetic operations

In this thesis, work is undertaken towards the design in hardware descri...

Fast Arbitrary Precision Floating Point on FPGA

Numerical codes that require arbitrary precision floating point (APFP) n...

MiniFloat-NN and ExSdotp: An ISA Extension and a Modular Open Hardware Unit for Low-Precision Training on RISC-V cores

Low-precision formats have recently driven major breakthroughs in neural...

Productivity meets Performance: Julia on A64FX

The Fujitsu A64FX ARM-based processor is used in supercomputers such as ...

Please sign up or login with your details

Forgot password? Click here to reset