RapidSmith is an open-source framework that allows for the exploration of novel approaches to the FPGA CAD flow for Xilinx devices. However, RapidSmith has poor support for manipulating designs below the slice level. In this paper, we highlight many of the projects RapidSmith enables and present extensions incorporated into "RapidSmith 2" that expose LUTs and flip-flops for direct manipulation in custom-built CAD tools. To demonstrate the utility of RapidSmith 2 we present the results of work to identify BELs in a design which must be clustered together and a tool that does pre-packing clustering accordingly.

FPGA designs often contain significant amounts of logic such as a board support package that remains unaltered throughout the design process. However, during normal operation, standard FPGA implementation tools re-implement the entire system, including the unchanged logic, adding to the turn around time of design iterations. Recently, FPGA implementation flows have appeared that allow preserving parts of a previously implemented design. In this study, we evaluate the potential speedups in implementation time achievable through preserving the unchanging portion of a design's implementation. We perform these evaluations using Xilinx Partitions, Xilinx SmartGuide, and the HMFlow rapid implementation tool.

This paper presents a novel IP core reuse strategy which reduces design time from days to hours for communication circuits such as digital radio receivers. This design productivity is obtained by leveraging a highly parameterized library of communication specific cores. These cores are described in IP-XACT XML with vendor extensions describing the timing behavior of their communication interfaces. A synthesis tool, called Ogre, was created that generates the communication interfaces between cores described in IP-XACT and synthesizes full designs from structural synchronous dataflow specifications. Design productivity improvements are demonstrated with several radio receiver designs.