A message-based processing system is disclosed. An input message received in the message-based processing system comprises a first indication of at least a subset of a plurality of processor elements and a second indication of a target pattern. Each of the plurality of processor elements has an addressable storage entry with a processor element address storing a processor element state. An initial address computation mode is selected from a set of address computation modes. A state value of each of the processor elements in the subset is updated based on magnitude values of respective pattern elements of the target pattern. A currently applied pattern element of the target pattern in each case determines whether to maintain a current address computation mode of the set of address computation modes or assume a next address computation mode selected from the set of address computation modes.