Method for the secure writing of a pointer for a ring buffer, associated ring buffer, use of the ring buffer and chip card with ring buffer

摘要

To permit safe writing of the pointer (P) pointing to the current record in a cyclic memory or ring memory, e.g. an EEPROM, the new record (D'#3) is written to the memory location (R3) containing the oldest record, and then the pointer (P) is updated. The pointer (P) consists of a first pointer (P1, P1*) and a second pointer (P2, P2*) redundant with respect to the first pointer. Each pointer contains a check value in the form of the inverse or complement code of the actual pointer. Due to the second pointer and the check value, the pointer is written with optimal safety. In case of a disturbance in the course of pointer updating, the old first pointer can later alternatively be recovered from the second pointer or the second pointer updated with the aid of the new first pointer.