[postgis-devel] alignment issues

[strk at refractions.net]

On Thu, Feb 10, 2005 at 03:56:22PM -0000, Mark Cave-Ayland wrote:
> Hi strk,
> 
> > -----Original Message-----
> > From: postgis-devel-bounces at postgis.refractions.net 
> > [mailto:postgis-devel-bounces at postgis.refractions.net] On 
> > Behalf Of strk at refractions.net
> > Sent: 10 February 2005 14:13
> > To: 'PostGIS Development Discussion'
> > Subject: Re: [postgis-devel] alignment issues
> 
> (cut)
>  
> > > I haven't had much experience with alignment issues, however this 
> > > looks like the easiest solution to me (e.g. you can declare 
> > a single 
> > > POINT2D in your function and then reuse it for the entire set of 
> > > POINT2Ds referenced within). I also noticed in the source that the 
> > > functions to do this already exist, for example getPoint2d_p....
> > 
> > Yes, but they are cheating, they call getPoint() internally 
> > ... --strk;
> 
> Really? Looking at RC2 I can't see any reference to getPoint() in
> getPoint2d_p(), plus the code looks fairly similar to getPoint() just below
> it...? Is this done in pointArray_ptsize() or in the serialized_pointlist[]
> array?

That one doesn't,  getPoint3dz_p and others do.. not much important,
I've already fixed them to not use casts. Also, I've renamed getPoint() to
getPoint_internal(), as it would still be useful to get a reference to
byte offset of a given point inside a POINTARRAY (tipically for setting
value of a specific point).

BTW, POINTARRAY management is not our only alignment-related issue.
We also have LWGEOM->bbox being a casted pointer to internal (serialized)
storage - easily fixed - and most notably the SERIALIZED_FORM() macro
which just moves the pointer 4 bytes after the start... 

These are big changes, but I think its worth completing before 1.0.

--strk;


> 
> 
> Kind regards,
> 
> Mark.
> 
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