Abstract: A simulation environment which limits the information stored about a variable's value is provided. The stored information can include a single full-range number and a small enumeration of information known about that value (e.g., equal to, not equal to, less than, greater than and/or unknown). With the addition of context information and a carefully constructed set of transition/combination tables, the accuracy of simulation in the simulation environment can be very high with very little information being stored or tested each time a simulated variable is accessed.

Abstract: A buffer, implemented in computer memory, that never wraps data around from the buffer end to the buffer beginning unless the amount of data being transferred exceeds the entire size of the buffer. Eliminating wrapping improves performance by eliminating the need for the reading device to reconstruct a contiguous block of data from multiple reads. In addition, when possible, only the beginning portion of the buffer is used, thereby minimizing the occurrence of virtual memory page faults during buffer use and increasing the probability that pages near the end of the buffer will be freed for uninterrupted use by other processes. In addition to the usual read and write pointers, the buffer in the invention adds two variables, a buffer end pointer and a marker. When necessary, the buffer end pointer indicates the end of a block of data. The marker is used to limit the use of the buffer memory to a few pages at the beginning of the buffer when possible.