US Patent 10007592 Debugging non-deterministic embedded systems

An embedded device includes a processor executing instructions from module(s) in a code memory. The instructions specify: reading data from two non-deterministic registers (NDRs) of different types, compressing the data using respective, different compression algorithms, and storing the compressed data in a nonvolatile medium. A method of enabling debug tracing in a computer program product (CPP) includes locating instructions in the CPP that read NDRs, determining types of the NDRs, and adding instruction(s) to the CPP to compress the values read using compression algorithms corresponding to the respective NDR types. An emulator in a computer-readable medium receives emulation-target instructions (ETIs) and compressed NDR data, and emulates an execution sequence of the ETIs by determining NDR-reading instructions, determining a type of the NDR read by each, decompressing a portion of the NDR data using a type-specific decompressor, and updating emulated-machine state based on the decompressed portion.