division of 32bit by 16bit in 8051 assembly

i want to do 32 bit division by 16bit in my project to produce velocity,
as velocity= dist/time
so plz tell me how to do division of 32bit by 16 bit in 8051

Simple answer: use a math library (include math.h)
Slightly longer answer: If the numbers are integers, just see how many times the denominator fits into the numerator (simple loop count). It will take a while to execute of course... You could take short-cuts if your time is a power of 2 (2^1, 2^2, 2^3..) then you could just do a bit-shift operation (shifting the numerator one position to the right is equivalent to divide-by-two.
If your numbers are not integers then you could round off, or scale up, or use a math library.

EDIT: sorry, just saw you wanted to do it in assembly. Unless you can find a math routine to do this, then you'll need to implement your own, perhaps using the scheme I mentioned. Since the 8051 is fairly common, you may find a routine on the Internet if you google it.