Re: Some thoughts on integer exponentiation (and an implementation)

[Sean Conner <sean@...>]

It was thus said that the Great Stefan Ginsberg once stated:
> 
> > On 14 May 2017, at 23:46, Sean Conner <sean@conman.org> wrote:
> > 
> >  Second, I'm not sure if I like returning nil.  
> > 
> >    a = 1
> >    b = 63
> >    c = 1
> > 
> >    x = (1 << b) + c
> > 
> >    stdin:1: attempt to perform arithmetic on a nil value
> >    stack traceback:
> >            stdin:1: in main chunk
> >            [C]: in ?
> >> 
> >  Okay, that doesn't happen now---what happens now is that x =
> > 9223372036854775807 instead of -9223372036854775809 because of rollover. 
> > I can see an argument for it, but ...
> > 
> To be clear that idea is only for the affected mathematical operators, not
> bitwise shifts.
> 
> I don't consider shifting out bits the same thing as overflow, it is
> another type of operation.

  Shifting is just multiplication or division by two.  At the CPU level,
there is a distinction made between shifts (left (multiplication) which
shifts in 0s and right (division) which shifts in the sign bit) and rotates
(shifts the bits, rotating in the carry bit).

  -spc