Event driven executive
Tasks may be planned for execution on a single processor or are split up by the designer for execution among a plurality of signal processors. The tasks are modeled using a design aid called a precedence graph, from which a dependency table and a prerequisite table are established for reference within each processor. During execution, at the completion of a given task, an end of task interrupt is provided from any processor which has completed a task to any and all other processors including itself in which completion of that task is a prerequisite for commencement of any dependent tasks. The relevant updated data may be transferred by the processor either before or after signalling task completion to the processors needing the updated data prior to commencing execution of the dependent tasks. Coherency may be ensured, however, by sending the data before the interrupt. When the end of task interrupt is received in a processor, its dependency table is consulted to determine those tasks dependent upon completion of the task which has just been signalled as completed, and task dependency signals indicative thereof are provided and stored in a current status list of a prerequisite table. The current status of all current prerequisites are compared to the complete prerequisites listed for all affected tasks and those tasks for which the comparison indicates that all prerequisites have been met are queued for execution in a selected order.