Re: [PATCH] rev-list: estimate number of bisection step left

> 2009/2/17 Johannes Schindelin <Johannes.Schindelin@gmx.de>:
>
> > On Tue, 17 Feb 2009, Christian Couder wrote:
> >
> >> +static int estimate_bisect_steps(int all)
> >> +{
> >> +     int log2 = 0;
> >> +     int left = (all >> 1) - 1;
> >> +
> >> +     if (left <= 0)
> >> +             return 0;
> >> +
> >> +     do {
> >> +             left = left >> 1;
> >> +             log2++;
> >> +     } while (left);
> >> +
> >> +     return log2;
> >> +}
> >
> > How about this instead, calling it from cmd_rev_list directly?
> >
> >        static int log2(int n)
> >        {
> >                int log2;
> >
> >                for (log2 = 0; n > 1; log2++)
> >                        n >>= 1;
> >
> >                return log2;
> >        }
> 
> This would work, if you want a non-iterative solution
> 
> unsigned int log2_integer_approximate(unsigned int n){
> *((float*)&n) = (float)n;
> return ((n & (~((1<<23) - 1))) >> 23) - 127;
> }