Abstract. Instruction selection for embedded processors is a challenging problem. Embedded system architectures feature highly irregular instruction sets and complex data paths. Traditional code generation techniques have difficulties to fully utilize the features of such architectures and typically result in inefficient code. In this paper we describe an instruction selection technique that uses static single assignment graphs (SSA-graphs) as underlying data structure for selection. Patterns defined as graph grammar guide the instruction selection to find (nearly) optimal results. We present an approach which maps the pattern matching problem to a partitioned boolean quadratic optimization problem (PBQP). A linear PBQP solver computes optimal solutions for almost all nodes of a SSA-graph. We have implemented our approach in a production DSP compiler. Our experiments show that our approach achieves significant better results compared to classical tree matching.

We introduce a local collaborative augmented reality environment for home based entertainment. We propose a setup for multiple users with see-through head-mounted displays, allowing dedicated stereoscopic views and individualized interaction for each participant. This hardware arrangement does not hinder social communication, which is essential for playing games. To maintain a high quality game experience we use facesnapping for fast and precise direct object manipulation. We derive semantic actions from snap events to pre-defined regions in the virtual gaming space. Combined with the game regions, we introduce a layering concept allowing individual views onto the common data structure.Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage, and that copies hear this notice and the full citation on the tirst page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. ACM l-58113-019-8/ 98/ 0011/%5.00This combination creates a powerful automatic privacy mechanism, which makes security management dispensable at runtime. We demonstrate our system with a board-game Mah-Jongg, that relies heavily on social communication and the need of private space.

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Recent work on compilation for DSP-processors deals with optimizing access to local variables of functions. The common way is to use one or more address registers as pointers into the functions stack frame and modify it with post modify addressing modes (which are sometimes the only addressing modes). Additionally to previous work we present an algorithm which assigns frame pointer values over a whole procedure. Our algorithm also deals with basic blocks, which have no accesses to local variables. The algorithm works with a new data structure, the control flow line graph, which is derived from the control flow graph. In our experiments, the algorithm showed improvements to similar algorithms.