Simple/Fast Algorithm for binary logarithm in C (on ARM7)

Hello all,

in a current ARM7 project I need to do some calculations which include a
logarithm. All other math is done with integers (i.e. fixed point
arithmetic), and I would like to calculate the log fast and with little
code - so I don't prefer using FP conversion and the standard math
libraries.

Can anyone point to fixed-point logarithmic routines I could use (resp.
tailor to my needs)?

Thanks,
Tilmann

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