The SHAP Bytecode Processor

• Introduction
• Benefits
• Features
• Workflow

Introduction

The SHAP bytecode processor has been developed at the VLSI-EDA Chair of the Faculty of Computer Science by Martin Zabel and Thomas Preußer since 2006. SHAP provides an embedded Java platform, which is readily available as a proven synthesizable IP core for implementation on FPGA devices and standard cells.

Benefits

SHAP gives you the opportunity to develop your embedded applications fast and efficiently in the widespread high-level Java programming language:

• Well-structured, flexible object-oriented application design.
• High development comfort with standard Java development tools.
• Safe and automatic memory and resource management.
• Programming against a rich standard CLDC API implementation.
• Support for reference queuing in extent of the CLDC.
• Simple debugging through self-localizing JVM exceptions.

Features

The SHAP platform is greatly flexible and can be easily customized to meet specific application needs and to incorporate new interfacing capabilities through custom Wishbone-attached on-chip controllers. The readily available interfacing technology ranges from a legacy RS232 UART all the way to ethernet LAN capabilities.

SHAP implements and pioneers a wide range of sophisticated technologies to provide an efficient and predictable execution environment, which makes it ideally suited of real-time applications:

• an optimizing application linker,
• a remote access for dynamic application loading and control,
• an efficient constant-time interface method dispatch,
• a preemptive scheduler ensuring autonomous control flows,
• a spill-free, on-chip spaghetti stack with autonomous thread and method frame management,
• a statically predictable method cache architecture,
• an independent, fully-concurrent, real-time hardware garbage collector with support for weak references and reference queuing,
• a full-duplex, multi-port, pipelined memory controller,
• a scalable multi-core architecture with proven system integrations of up to 18 cores,
• a parallel, multi-core-capable hardware trace architecture for detailed application analysis.

Workflow

SHAP runs applications written in regular Java and compiled with a regular Java compiler. The produced standard class files or application JARs are processed by the ShapLinker, which produces a SHAP application bundle, which can be downloaded directly to a SHAP platform hardware. SHAP can run multiple applications concurrently in mutual isolation. A remote access system service provides supervisor access and establishes communication links dynamically.

We have worked hard to provide such a comfortable application workflow. This may be best understood by contrasting it to our own system design workflow: