Optimized synthesis of concurrently checked controllers

A method for introducing online test facilities in a controller with a very low overhead is presented. This online test consists of detecting illegal paths in the control flow graph. These illegal paths may be due either to permanent faults or to transient errors. The state code flow is compacted through polynomial division. An implicit justifying signature method is applied at the state code level and ensures identical signatures before each join mode of the control flow graph. The signatures are then independent of the path followed previously in the graph, and the comparison to reference data is greatly facilitated. This property is obtained by a state assignment, nearly without area overhead. The controllers can then be checked by signature analysis, either by a built-in monitor or by an external checker