Implementation of reader-writer locks based on multimedia DSP

With the structure of Digital Signal Processor (DSP) application program getting more complex, there is a rise in the need for concurrent access to shared resources under a multitasking environment. However, the task scheduling and synchronization provided by most of the DSP operating systems is quite limited, which can barely meet the requirement of the control of concurrent access. At present, reader-writer (RW) locks have been in wide-spread use for many POSIX-compliant real-time operating systems to provide currency control, but they can not be applied to DSP operating systems without any change. In this paper, a locking system is proposed as a realization form of RW locks, which provides control of concurrent access based on the Application Programming Interface (API) in DSP operating systems. Meanwhile, to avoid the occurrence of priority inversion and livelock, an enhanced compatibility matrix working with priority inheritance protocol is introduced in this system. The experimental result shows that the locking system can function properly under a multitasking environment, and its performance is superior to that of the traditional one using strict mutual exclusive (mutex) matrix.