Keep STB_DXT_DITHER so as not to break existing code that tries
to enable it, but just leave it permanently off. I originally
introduced it somewhat superstitiously because of the RGB565
endpoint resolution but it never improved either perceptual quality
or objective quality metrics, and the code is appreciably simpler
without it.
Also fix a "potentially uninitialized variable" warning.
This is a modified version of Alan's original PR that keeps the
table generator in the file (in case there's interest) and also
replaces the expand[] tables with math, since it's trivial.
Fixes issue #1117.
Put the formats that start with a clear magic number first,
the dodgy ones that don't have much of a distinctive header
should be tested for later after we've ruled out the clearer
ones.
Fixes issue #787, hopefully. (Never got a clean repro.)
It's implementation-specified behavior. Writing this code and then
relying on compiler strength reduction to turn it back into shifts
feels extremely silly but it is what it is.
Fixes issue #1097.
Define lrot in a way that doesn't involve UB when n==0.
Also, the previous patch ensures that n <= 15 for all callers
of stbi__extend_receive, so can remove the (less restrictive)
bounds check for 0 <= n < 17 (the bounds of stbi__bmask)
entirely.
Fixes issue #1065.
extend_receive implicitly requires n <= 15 (code length);
the maximum that actually makes sense for 8-bit baseline JPEG is
11, but 15 is the natural limit for us because the AC coding path
stores the number of magnitude bits in a nibble.
Check that DC delta bits are in range before attempting to call
extend_receive.
Fixes issue #1108.
Keep STB_DXT_DITHER so as not to break existing code that tries
to enable it, but just leave it permanently off. I originally
introduced it somewhat superstitiously because of the RGB565
endpoint resolution but it never improved either perceptual quality
or objective quality metrics, and the code is appreciably simpler
without it.
Also fix a "potentially uninitialized variable" warning.
This is a modified version of Alan's original PR that keeps the
table generator in the file (in case there's interest) and also
replaces the expand[] tables with math, since it's trivial.
Fixes issue #1117.
