Token train retrieval device for simultaneously determining nest level

Abstract

In a token train retrieval device including a memory device (24) for memorizing a plurality of tokens each of which starts at a starting address and ends at an end address and each of which has a nest level selected from a plurality of nest levels and comprises a header and a data set where header comprises a data length code and a data identifier code including a nest bit, a retrieval condition memory (25) memorizes a retrieval condition including a plurality of designated nest level codes and a plurality of designated identifier codes. A header register (26) holds the data length code, the data identifier code, and the nest bit as a held data length code, a held data identifier code, and a held nest bit. Responsive to the held data length code, a supplied header, and a decided nest level code, a checking circuit (27) produces a matching signal when the retrieval condition is satisfied. An intra-train address generating circuit (29) generates an intra-train address variable in accordance with the matching signal and the held data length code. Supplied with the intra-train address and the held data length code, an end address calculating circuit (30) calculates the end address of each token as a calculated address. Responsive to the intra-train address, the calculated address, and the held nest bit, a nest level decision circuit (31) supplies the checking circuit with the decided nest level code indicative of one of the nest levels.