Given that input_time actually represents an integer value in seconds since the epoch - and has the value 0 at precisely "Thu Jan 1 00:00:00 1970", write a better implementation of this function.

1: unsigned long normalise(unsigned long input_time)
2: {
3:
4: bool finished;
5:
6: // This produces a formatted time string like:
7: // Thu_Nov_24_18:22:48_1986
8: string str_time = format_time( input_time );
9:
10: while( str_time.substr(1,3) != "Sun")
11: {
12: input_time -= 24*60*60;
13: str_time = format_time( input_time );
14: }
15:
16: while( str_time.substr(11,2) != "00" )
17: {
18: input_time -= 60*60;
19: str_time = format_time( input_time );
20: }
21:
22: while( str_time.substr(14,2) != "00")
23: {
24: str_time = format_time( input_time );
25: input_time -= 60;
26: }
27:
28: while( str_time.substr(17,2) != "00")
29: {
30: input_time -= 1;
31: str_time = format_time( input_time );
32: }
33:
34: return input_time;
35: }