RE: computer-go: Sharing Go modules

[David Fotland <fotland@xxxxxxxxxxxxxxx>]

At 03:37 PM 5/16/2001 -0700, you wrote:
> Could you explain why a 2D array can cause a performance problem?

Take a look at the assembler output with a debugger.  To get the memory
address for a 2d 19x19 array, there is a multiply by 19.  A one dimensional
array avoids the multiply.  If the computer has index addressing mode, a
single instruction can get the array value.

David


> Thanks.
>
> -- Mousheng Xu
>
> -----Original Message-----
> From: Anders Kierulf [mailto:anders@xxxxxxxxxxxxxxxxx]
> Sent: Wednesday, May 16, 2001 8:33 AM
> To: computer-go@xxxxxxxxxxxxxxxxx
> Subject: RE: computer-go: Sharing Go modules
>
>
> > The coordinate coding method that I use is X,Y converts to X+Y*20. The
> > arrays are all 421 long where all te points at 0,Y and X,0 contain special
> > values to make it easy to detect the edge of the board. This is a
> convenient
> > coding since it's still fairly easy to see which coordinates they
> represent
> > (for example: 63 is 3,3 and 356 is 16,17). However I do realise that every
> > Go programmmer has their own idea of how this should be done and that
> > there's little chance that I can convince everyone in the world to use
> this
> > scheme (that would be nice though <grin>) instead of using separate X and
> Y
> > coordinates.
>
> This is a good scheme. It's the same scheme SmartGo uses, so at least two Go
> programs have independently reached exactly the same solution. Please go
> ahead and convince the rest of the world. :-)
>
> Anders Kierulf
> www.smartgo.com
>
>
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David Fotland