Interrupt and Low-level Programming Support for Expanding the Application Domain of Statically-Scheduled Horizontal-Microcoded Architectures in Embedded Systems

The increasing role of software in the embedded systems has made processor an important component in these systems. However, to meet the tight constraints of embedded application, it is often required to customize the processor for the application. Customizing instruction-based processors is difficult and very challenging. Design approaches based on statically-scheduled horizontal-microcoded architectures have been proposed to simplify the architecture customization. In these approaches, first the datapath is specified by the designer, and then the operations of the datapath are extracted automatically. Since the operations are statically scheduled in these architectures (i) low-level programming using assembly is impossible or very tedious; and (ii) execution of programs cannot be interrupted arbitrarily. This paper addressed the above problems. The paper shows how to efficiently handle interrupts in such architectures and also propose an elegant way of controlling low-level hardware resources in a general way in C language. The authors also show that after adding interrupt and low-level programming that could use the above architectural style in a multi-core system to implement a complete MP3 decoder that can process 122 frames per second while the standard requirement is 38 frames per seconds