Abstract: An apparatus (900) for performing the steps of data compression and data expansion. Where the steps of compression of use a modulo arithmetic unit (915) for identifying matching blocks of data that are offset from each other by a multiple of N. A matching block of data is compressed by the apparatus (900) by replacing it with an escape sequence representing the size and offset of the matching block of data. The apparatus (900) identifies a least used data value for use as an escape character to identify the escape sequence. The apparatus (900) performs data expansion by identifying escape sequences and locating an expanded block of data that matches the data represented by the escape sequence by multiplying the offset represented in the escape character by N to specify the offset to the expanded block of data.

Abstract: A method for processing exception conditions in a floating-point system (40) begins by determining in hardware that an exception will occur (14) for a given floating-point operation and operand(s). After the hardware determines that an exception is to occur, an exception handler is invoked from software. The exception handler numerically alters the operands to create biased operands which may be processed by the hardware (20) via the given floating-point operation without creating another exception condition. The biased operands are then processed by the hardware via the given floating-point operation to produce a biased floating-point result. The biased floating-point result is unbiased (22) by the exception handler to achieve an unbiased result. The speed of floating-point exception handling is improved by using biasing techniques and both software and hardware to mathematically resolve floating-point exceptions to correct unbiased results.

Abstract: A dynamic instruction modifying controller (10, 11, or 13) and controller method of operation for use with a general purpose computer. The controller has an execution device (12) and a memory (14). Residing in memory (14) is a control program (16). Control program (16) communicates to the execution device via a conductor (22). A target program (18) resides in memory (14) and communicates with the control program (16) via a conductor (24). A modifying program (20) resides in memory (14) and communicates to the control program (16) via a conductor (28). The modifying program (20) alters the target program (18) during target program (18) execution time to include the execution of a surrogate code group created by the modifying program (20).