[vsipl++] [patch] Fix for generic pwarp

[Stefan Seefeld]

Jules Bergmann wrote:
> Stefan,
> 
> This patch attempts to fix the generic pwarp impl so that it doesn't
> access memory past the end of the input image.
> 
> Can you give a spin on windows to see if it fixes the segfault?

Unfortunately it still fails.
Luckily, though, I have been able to reproduce the failure under Linux,
using ElectricFence, and it seems to be the exact same place as on
Windows, at least if I trust the debugger(s):

pwarp_gen.hpp:237

In line 232:

p = p_in + v0*in_stride_0 + u0;

becomes

p_in + 511 * 512 + 503;

(which is still legal, as the block size is 512x512) but then in line
237 we have

z11 = *(p + in_stride_0 + 1)

which is

p + 512 + 1

i.e. we are dereferencing the block at index (v0+1)*in_stride_0 + u0
(i.e. 512*512 + something) which is clearly too big. I don't immediately
see where the failure is, and so I'm sending this out without a fix. May
be someone beats me to it <wink/>.

Thanks,
		Stefan

-- 
Stefan Seefeld
CodeSourcery
stefan at codesourcery.com
(650) 331-3385 x718