Efficient multi-users timer.

摘要

A system for providing a plurality of timers to perform the timing of event occurrences wherein to each event corresponds a timer control block (210) which stores in its time_flag (Tf) the indication of whether the timer control block is chained or unchained, running or stop, in its time_out (Tv) the expiration time interval and in its time-stamp (Ts) the current time as a reference at each interruption for further treatments. The timer control blocks are chained by a one-way link (250) according to their expiration times in a way that each timer chain comprises the timer control blocks whose events will occur at the same time. A cyclic table (202) of index enables to classify the timer chains according to their expiration times, each one being pointed by an index. When a START operation is requested for an event which has to occur in a time_out value, an index is computed according to the Tv and the current time in order to insert its corresponding timer control block at the head of the timer chain pointed by said index, said timer control block storing the state of CHAINED-RUNNING in its time-flag and the current time in its time_stamp, if the timer control block is already chained, then updating only the timer_stamp to the current time and the time_flag to running because it has previously been stopped by the user. Whenever a RESTART operation is requested for an event before it has occurred, the time_stamp of the corresponding timer control block is updated to the value of the current time. Whenever a STOP operation is requested before the event has occurred, its time_flag is updated to "STOP". Meanwhile the time_stamps and the time_flags are updated according to the START, STOP and RESTART operations, the current index of the cyclic table is incremented at each time_tick to delete the timer control blocks of the chain whose events have occurred or whose time_out values have expired, and to insert new timer control blocks in the new timer chain for those which have been interrupted and whose events have not occurred yet. <IMAGE>