The convention used by libjpeg:
type * variable;
is not very common anymore, because it looks too much like
multiplication. Some (particularly C++ programmers) prefer to tuck the
pointer symbol against the type:
type* variable;
to emphasize that a pointer to a type is effectively a new type.
However, this can also be confusing, since defining multiple variables
on the same line would not work properly:
type* variable1, variable2; /* Only variable1 is actually a
pointer. */
This commit reformats the entirety of the libjpeg-turbo code base so
that it uses the same code formatting convention for pointers that the
TurboJPEG API code uses:
type *variable1, *variable2;
This seems to be the most common convention among C programmers, and
it is the convention used by other codec libraries, such as libpng and
libtiff.
The IJG README file has been renamed to README.ijg, in order to avoid
confusion (many people were assuming that that was our project's README
file and weren't reading README-turbo.txt) and to lay the groundwork for
markdown versions of the libjpeg-turbo README and build instructions.
Most of these involved left shifting a negative number, which is
technically undefined (although every modern compiler I'm aware of
will implement this by treating the signed integer as a 2's complement
unsigned integer-- the LEFT_SHIFT() macro just makes this behavior
explicit in order to shut up ubsan.) This also fixes a couple of
non-issues in the entropy codecs, whereby the sanitizer reported an
out-of-bounds index in the 4th argument of jpeg_make_d_derived_tbl().
In those cases, the index was actually out of bounds (caused by a
malformed JPEG image), but jpeg_make_d_derived_tbl() would have caught
the error and aborted prior to actually using the invalid address. Here
again, the fix was to make our intentions explicit so as to shut up
ubsan.
