Re: [pygame] pygame parachute and inconsistent interned sting state - but only on Slackware 13.0 32 bit

[Peter Chant <pete@xxxxxxxxxxxxxxx>]

Thank to Rene, Claudio and Brian,

On Wednesday 16 September 2009, Brian Fisher wrote:
> Well that looks like a very complicated way to clear the screen, which also
> involves blitting a surface to itself (you are blitting the
> pygame.display.get_surface() to the pygame.display.get_surface() after
> clearing the surface)
>

Claudio said much the same thing.  I must admit it looked over complicated 
when I put it in the email.  This is my roughly my second attempt at something 
non-trivial with python so I am very much a learner.  

> The symptoms of your original bug report seem remarkably similar to a bug
> that existed in SDL with blitting a surface to itself due to a change in
> gcc 4.0 (it stopped restoring the direction flag). The exact problem in
> that case was that the SDL code to blit a surface to itself was special
> cased, and that special case assumed the direction flag was cleared when it
> did a rep movsb. But since it wasn't with the new gcc, if the direction
> flag had been set elsewhere, then the copy went in the other way and either
> corrupted memory, resulting in that string state error message, or crashed

Slack 13.0 64 bit:  		gcc 4.3.3   sdl  1.2.13
Slack 13.0 32 bit:  		gcc 4.3.3   sdl  1.2.13
Slack 12.0 (32 bit only)	gcc 4.2.4   sdl  1.2.13

>
> I don't recall how that old bug was (or was not) resolved for pygame, but
> there is history on that bug on the list archive.
>
> Lenard probably remembers it much better than me.
>
> ... but you could also fix this by replacing thatvery  convoluted
> clearScreen body with a simple self.screen.fill((0,0,0))

Yes, works, I also ought to put that function somewhere more sensible as 
well...

Thanks All,

Pete
-- 
Peter Chant
http://www.petezilla.co.uk