Method of driving timer in an advanced intelligent network switching system employing the thread call structure under UNIX system

A method for providing an AIN (Advanced Intelligent Network) switching system employing a thread call structure having a plurality of timers variably corresponding to a plurality of produced threads, said method comprising the steps of:

• providing a plurality of timer items having a variable correspondence to said plurality of produced threads as needed, without fixing a number of the plurality of timers according to a number of the plurality of threads;
• providing a head item in front of said plurality of timer items and a null item at the end of said plurality of timer items in the opposite end of said head item to engage a timer drive process every second, said head item includes a pointer which points to a timer item having a shortest count data;
• arranging said plurality of timer items having a shortest count data to a longest count data in sequence to form a double linked list structure;
• sequentially reducing the count data of each said timer item in sequence and simultaneously detecting a time-out state of said timer item;
• informing said produced thread corresponding to said timer item with said time-out state;
• deleting said produced thread with said time-out state from the double linked structure sequence and coupling together adjacent threads that were connected at opposite ends of said produced thread prior to deletion so as to maintain said double linked structure;
• terminating the step of sequentially reducing the count data of each timer item in said timer list upon detecting said null timer item.