Generation of Customized RISC-V Implementations

Processor customization has become increasingly important for achieving better performance and energy efficiency in embedded systems. However, customizing processors is time-consuming and error-prone work. The design effort is reduced by describing the processor architecture with high-level languages that are then used to generate the processor implementation. In addition to processor customization, open source hardware and standardization have become increasingly more popular. RISC-V that is a relatively new open standard instruction set architecture, has gained traction both in academia and industry. This thesis work added a RISC-V extension to the OpenASIP toolset that is developed at Tampere University. OpenASIP has wide support for customizing and generating transport triggered architectures. Transport triggered architectures have an exposed datapath that is visible to the programmer, which allows a lower level programming interface. The hardware generation and customization features in OpenASIP were reused by utilizing a transport triggered architecture as the internal microarchitecture together with a microcode unit. The extension generates the RISC-V implementations from an architecture description, which reduces the design effort of customizing the implementation. The RISC-V generator developed in this thesis has customization points for the bypass network, amount of pipeline stages, operation latencies and an optional addition of the standard M extension. The generator was evaluated by generating RISC-V cores with different customization points and comparing their performance and post-synthesis properties with open source implementations. The generated cores with bypass network achieved better performance while consuming slightly more area than the smallest reference design. The microcode hardware only utilized 3.6% of the design area and did not affect the maximum clock frequency

Instruction Set Extension of a Low-End Reconfigurable Microcontroller in Bit-Sorting Implementation

The microcontroller-based system is currently having a tremendous boost with the revelation of platforms such as the Internet of Things. Low-end families of microcontroller architecture are still in demand albeit less technologically advanced due to its better I/O better application and control. However, there is clearly a lack of computational capability of the low-end architecture that will affect the pre-processing stage of the received data. The purpose of this research is to combine the best feature of an 8-bit microcontroller architecture together with the computationally complex operations without incurring extra resources. The modules’ integration is implemented using instruction set architecture (ISA) extension technique and is developed on the Field Programmable Gate Array (FPGA). Extensive simulations were performed with the and a comprehensive methodology is proposed. It was found that the ISA extension from 12-bit to 16-bit has produced a faster execution time with fewer resource utilization when implementing the bit-sorting algorithm. The overall development process used in this research is flexible enough for further investigation either by extending its module to more complex algorithms or evaluating other designs of its components

Test exploration and validation using transaction level models

The complexity of the test infrastructure and test strategies in systems-on-chip approaches the complexity of the functional design space. This paper presents test design space exploration and validation of test strategies and schedules using transaction level models (TLMs). Since many aspects of testing involve the transfer of a significant amount of test stimuli and responses, the communication-centric view of TLMs suits this purpose exceptionally wel

Survey on Instruction Selection: An Extensive and Modern Literature Review

Instruction selection is one of three optimisation problems involved in the code generator backend of a compiler. The instruction selector is responsible of transforming an input program from its target-independent representation into a target-specific form by making best use of the available machine instructions. Hence instruction selection is a crucial part of efficient code generation. Despite on-going research since the late 1960s, the last, comprehensive survey on the field was written more than 30 years ago. As new approaches and techniques have appeared since its publication, this brings forth a need for a new, up-to-date review of the current body of literature. This report addresses that need by performing an extensive review and categorisation of existing research. The report therefore supersedes and extends the previous surveys, and also attempts to identify where future research should be directed.Comment: Major changes: - Merged simulation chapter with macro expansion chapter - Addressed misunderstandings of several approaches - Completely rewrote many parts of the chapters; strengthened the discussion of many approaches - Revised the drawing of all trees and graphs to put the root at the top instead of at the bottom - Added appendix for listing the approaches in a table See doc for more inf

Static resource models for code generation of embedded processors

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Application Specific Instruction Set Processor (ASIP) Design in an 8-bit Softcore Microcontroller

The microcontroller-based system is currently having a tremendous boost in demand in line with the Industrial Revolution 4.0. Although more applications seem to concentrate on software algorithms and wireless connectivity, the hardware side of the system is still occupied by microcontroller variants. With huge alternatives being offered to setup a microcontroller system, having a softcore microcontroller is extremely beneficial especially when considering the rapid advancement in computer technology. Although the 8-bit microcontroller has less computational capability compare to other high-end microcontroller families, it has an advantage in low code density for I/O application and control. The purpose of this research is to combine the best feature of the 8-bit architecture together with efficient arithmetic operations in the implementation of moving average filter. The modules’ integration is implemented using ASIP design without occurring extra board space and is developed using the Field Programmable Gate Array (FPGA) as the single chip solutions. It was found that the revised microcontroller architecture has produced a faster execution time and similar maximum frequency when benchmarked with its predecessor. The overall ASIP design procedures used in this research provides flexibility for further development, either by extending its module to incorporate more complex algorithms or by upgrading current designs of its components