A High Performance Java Card Virtual Machine Interpreter Based on an Application Specific Instruction-Set Processor

Java Card is a Java running environment specific for smart cards. In such low-end embedded systems, the execution time of the applications is an issue of first order. One of the components of the Java Card Virtual Machine (JCVM) playing an important role in the execution speed is the bytecode interpreter. In Java systems the main technique for speeding-up the interpreter execution is the Just-In-Time compilation (JIT), but this resource consuming technique is inapplicable in systems with as restricted resources available as in smart cards. This paper presents a hardware/software co-design solution for the performance improvement of the interpreter. In the software domain, we adopted a pseudo-threaded code interpreter that allows a better run-time performance with a small amount of additional code. In the hardware domain, we proceeded moving parts of the interpreter into hardware, giving origin to a Java Card interpreter based on an application specific instruction set processor.