questuk wrote:
>
> Does anyone have a routine that divides a 16 bit number by another
> 16 Bit number, and gives the result to 2 decimal places
> (i.e.answer= 1663.65). I have looked all over the web and this site
> and cannot find one. I have looked at Microchip AN575 but sorry it
> lost me!
>

Assume the number is stored in memory as:
  (MS Byte)(LS Byte)
There is a binary point (decimal point equivalent for binary numbers) to
the right of the LS byte of the number. So if we consider the number as:
  (MS Byte)(LS Byte).(00000000)
which is a 24-bit binary number with the least significant bit
representing the number 1/256 (= 0.00390625 in decimal) or about 2.5
decimal places of precision.

Dividing the 24-bit number by a 16 bit number (using any of the
appropriate techniques) results in a number that should fulfill your
requirements.

  Consider 51966 divided by 64:
   51966 = 0xCAFE = 1100101011111110 = 1100101011111110.00000000
       I chose the 64 for simplicity, to show how this works, since
       dividing by 64 is just a right shift of 6 bits, therefore just
       like moving the binary point left 6 bits,
          1100101011111110.00000000/64
        = 1100101011.11111000000000
       of course in memory this would look like
    (11001010)(11111110).(00000000)  before divide
    (00000011)(00101011).(11111000)  after divide
       which is 512+256+32+8+2+1+(1/2)+(1/4)+(1/8)+(1/16)+(1/32)
       or  811.96875


David W. Gulley
Destiny Designs

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