Mechanism of method invocation and return in real-time embedded Java processor

In the aspect of real-time Java, RTSJ makes a series of effective work and provides the criteria for researches. In order to provide efficient execution platform for real-time Java, a RTSJ-oriented 32-bit embedded processor that can directly execute Java bytecodes-JPOR-32 was designed. Among Java bytecodes, the method invocation and return instructions are extraordinary complex. Executing these instructions is time-consuming and the Worst Case Execution Time (WCET) of them is hard to predict. This paper analyzes detailedly the method invocation and return mechanism of JPOR-32. Through the preprocessor module, JPOR-32 accomplishes the unreal-time run-time operations in advance, and achieved WCET predictability. Besides, the method invocation and return instructions are optimized in JPOR-32 and the static conversion from bytecodes to microcodes is accomplished in the image files. Combined with the instruction refetching and buffering scheme as well as the optimized design of the run-time stack structure, JPOR-32 provides effective supports for the method invocation and return of Java.