Unified Posit/IEEE-754 Vector MAC Unit for Transprecision Computing

Abstract

Transprecision computing targets energy-efficiency with multiple floating-point modules with different precisions to suit application requirements. Variable-precision architectures aim at making a more efficient hardware resource utilization, but they often rely on the IEEE-754 standard, without low-precision arithmetic support. Alternatively, the Posit format is particularly well-suited for low-precision arithmetic. However, for higher precisions, hardware requirements become prohibitive. Accordingly, this brief proposes a new unified Posit/IEEE-754 Vector Multiply-Accumulate (VMAC) unit, comprising a vectorized variable-precision datapath with shared support for the Posit and IEEE-754 formats. A 28nm ASIC implementation resulted in 50&#x0025; less area and <inline-formula> <tex-math notation="LaTeX">$2.9\times $ </tex-math></inline-formula> less power consumption than typical transprecision setups.