Abstract
Data-driven array architectures seem to be important alternatives for coarse-grained reconfigurable computing platforms. Their use has provided performance improvements over microprocessors and shorter programming cycles than FPGA-based platforms. As with other architectures, in data-driven architectures loop pipelining plays an important role to improve performance. Usually this kind of pipelining can be achieved using the dataflow software pipelining technique or other software pipelining approaches. Although performance improvements are achieved, those techniques heavily depend on the insertion of pipelining stages and thus require complex balancing efforts. Furthermore, those techniques statically define the pipelining and do not take fully advantage of the dynamic scheduling attainable by the data-driven concept. This paper presents a novel scheme to pipeline loops in data-driven architectures, orchestrated by a handshaking protocol. Using the new approach, self loop pipelining is naturally achieved. The scheme is based on duplicating cyclic hardware structures, in order they are autonomously executed, with synchronization being achieved by the data flow. It can be applied to nested loops, requires less aggressive pipeline balancing efforts than usual software pipelining techniques, and innermost loops with conditional structures can be pipelined without conservative pipelining implementations. We show results of using the proposed technique when mapping algorithms in imperative programming languages to the PACT eXtreme Processing Platform (XPP). The results confirm improvements over the use of conventional loop pipelining techniques. Better performance and fewer resources are achieved in a number of cases. Copyright 2005 ACM.

Abstract
This work presents further enhancements to an environment for exploring coarse grained reconfigurable data-driven array architectures suitable to implement data-stream applications. The environment takes advantage of Java and XML technologies to enable architectural trade-off analysis. The flexibility of the approach to accommodate different topologies and interconnection patterns is shown by a first mapping scheme. Three benchmarks from the DSP scenario, mapped on hexagonal and grid architectures, are used to validate our approach and to establish comparison results.

Abstract
The eXtreme Processing Platform (XPP) is a coarse-grained dynamically reconfigurable architecture. Its advanced reconfiguration features make feasible the configure-execute paradigm, the natural paradigm of dynamically reconfigurable computing. This chapter presents a compiler aiming to program the XPP using a subset of the C language. The compiler, apart from mapping the computational structures onto the available resources on the device, splits the program in temporal sections when it needs more resources than the physically available. In addition, since the execution of the computational structures in a configuration needs at least two stages (e.g., configuring and computing), a scheme to split the program such that the reconfiguration overheads are minimized, taking advantage of the overlapping of the execution stages on different configurations is presented. © 2005 Springer.

Abstract
Reconfigurable computing has already confirmed a significant potential for accelerating certain computing tasks. However, the most successful applications relied on user expertise to design a specific architecture implemented by the hardware structures of the reconfigurable computing device. Hence, one of the most challenging issues is to map, efficiently and automatically, computations (described in software programming languages) to reconfigurable computing devices. This paper presents CHIADO, a research project aiming a compiler framework to map efficiently software programs to reconfigurable computing platforms, especially the ones based on FPGA (Field-Programmable Gate Array) devices. The framework is also intended to support research of new optimization techniques. The project, based on our previous work on compiling Java bytecodes to FPGAs, focuses on high-performance solutions, schemes to estimate the impact of some transformations supported by the compiler (partial/full loop unrolling), and schemes to take advantage of dynamic reconfiguration (e.g., temporal partitioning). This paper gives an overview about the CHIADO project, shows the framework, and enumerates the main project goals.

Abstract
The von Neumann-style architectures have been tremendously well succeeded by taking advantage of the Moore's law. It is now understood that, it will be very difficult to meet the supercomputing demands of the future computing systems with this style of microprocessor architectures. Most nowadays applications require high-performance for processing data streams. Being dataflow computing a natural paradigm to process data streams, architectures based on dataflow principles are emerging as a way to meet the supercomputing demands. Data-driven arrays, introduced in the 80's, are examples of such architectures. They devised a scalable and effective fashion to directly support the dataflow model of computation and have been revived by a number of reconfigurable architectures (e.g., KressArray, WaveScalar, and XPP). Those coarse-grained reconfigurable architectures with dataflow semantics depict interesting achievements with respect to performance and programming methodologies, when compared to other computing platforms. This paper presents the most interesting data-driven array architectures. Trends and open issues related to a number of properties at architectural level and to compilation techniques are enumerated and discussed. A number of features are illustrated, especially the support for hardware virtualization, speculative configuration, and software pipelining. Examples using the PACT XPP reconfigurable array are shown. Those examples include the ADPCM decoder, from the MediaBench repository, and LeeDCT, an optimized DCT algorithm.

Abstract
This paper presents an infrastructure to verify the functionality of the specific architectures generated by a high-level compiler, targeting dynamically reconfigurable hardware. Java, XML, and XSL technologies are used to support the infrastructure. As simulation engine we use Hades, an event driven Java based simulator. It results in a suitable scheme to test the designs generated by the compiler each time a new optimization technique is included or changes in the compiler are performed. We believe this infrastructure will be very important to verify, by functional simulation, further research techniques, as far as compilation to FPGA-based reconfigurable computing is concerned.