OK Kari, you ACTUALLY dont have a problem. It is your problem of migrating from HLL to a low level language like assembly code.

Going back to your description, all you need is one sample per hour and using a moving average method at a sampling rate of 0.5 secs ( I am just guessing ) you will need about 8 secs or so to get in about 16 samples at the change of the hour... using Hans code.

Now at the end of the day if you have managed to add these 24 averaged values to a 16 bit location, the worst case value will be 0x17E8 and you have to divide this by 24 to get the mean - not a difficult task again. And if you want to retain precision just multiply the average by 10 and adjust your decimal after the division. So where is the problem ?

Raghu