With rare exceptions ...
- Always separate line continuation characters by one space from
preceding code.
- Always use two-space indentation. Never use tabs.
- Always use K&R-style conditional blocks.
- Always surround operators with spaces, except in raw assembly code.
- Always put a space after, but not before, a comma.
- Never put a space between type casts and variables/function calls.
- Never put a space between the function name and the argument list in
function declarations and prototypes.
- Always surround braces ('{' and '}') with spaces.
- Always surround statements (if, for, else, catch, while, do, switch)
with spaces.
- Always attach pointer symbols ('*' and '**') to the variable or
function name.
- Always precede pointer symbols ('*' and '**') by a space in type
casts.
- Use the MIN() macro from jpegint.h within the libjpeg and TurboJPEG
API libraries (using min() from tjutil.h is still necessary for
TJBench.)
- Where it makes sense (particularly in the TurboJPEG code), put a blank
line after variable declaration blocks.
- Always separate statements in one-liners by two spaces.
The purpose of this was to ease maintenance on my part and also to make
it easier for contributors to figure out how to format patch
submissions. This was admittedly confusing (even to me sometimes) when
we had 3 or 4 different style conventions in the same source tree. The
new convention is more consistent with the formatting of other OSS code
bases.
This commit corrects deviations from the chosen formatting style in the
libjpeg API code and reformats the TurboJPEG API code such that it
conforms to the same standard.
NOTES:
- Although it is no longer necessary for the function name in function
declarations to begin in Column 1 (this was historically necessary
because of the ansi2knr utility, which allowed libjpeg to be built
with non-ANSI compilers), we retain that formatting for the libjpeg
code because it improves readability when using libjpeg's function
attribute macros (GLOBAL(), etc.)
- This reformatting project was accomplished with the help of AStyle and
Uncrustify, although neither was completely up to the task, and thus
a great deal of manual tweaking was required. Note to developers of
code formatting utilities: the libjpeg-turbo code base is an
excellent test bed, because AFAICT, it breaks every single one of the
utilities that are currently available.
- The legacy (MMX, SSE, 3DNow!) assembly code for i386 has been
formatted to match the SSE2 code (refer to
ff5685d5344273df321eb63a005eaae19d2496e3.) I hadn't intended to
bother with this, but the Loongson MMI implementation demonstrated
that there is still academic value to the MMX implementation, as an
algorithmic model for other 64-bit vector implementations. Thus, it
is desirable to improve its readability in the same manner as that of
the SSE2 implementation.
* libjpeg-turbo/master: (140 commits)
Increase severity of tjDecompressToYUV2() bug desc
Catch libjpeg errors in tjDecompressToYUV2()
BUILDING.md: Fix "... OR ..." indentation again
BUILDING.md: Fix confusing Windows build reqs
ChangeLog.md: Improve readability of plain text
change.log: Refer users to ChangeLog.md
Markdown version of ChangeLog.txt
Rename ChangeLog.txt
README.md: Link to BUILDING.md
BUILDING.md and README.md: Cosmetic tweaks
ChangeLog: "1.5 beta1" --> "1.4.90 (1.5 beta1)"
Java: Fix parallel make with autotools
Win/x64: Fix improper callee save of xmm8-xmm11
Bump TurboJPEG C API revision to 1.5
ChangeLog: Mention jpeg_crop_scanline() function
1.5 beta1
Fix v7/v8-compatible build
libjpeg API: Partial scanline decompression
Build: Make the NASM autoconf variable persistent
Use consistent/modern code formatting for dbl ptrs
...
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.
There was an oversight in the extension framework. jpeg_start_compress() can
be called multiple times between the time that a compress structure is created
and the time it is destroyed. If this happened, then the following sequence
would occur:
-- heap alloc of master struct within jpeg_create_compress()
-- heap free of master struct within jinit_c_master_control()
-- static alloc of extended master struct (JPOOL_IMAGE) within
jinit_c_master_control()
-- free extended master struct in jpeg_finish_compress()
-- jinit_c_master_control() now sees that cinfo->master is set and tries to
free it, even though it has already been freed. Chaos ensues.
The fix involved breaking out the extended master struct into a header so that
jpeg_create_compress() can go ahead and allocate it to the correct size, thus
eliminating the need to free and reallocate it in jinit_c_master_control().
Further, the master struct is now created in the permanent pool, so it will
survive until the compression struct is destroyed. Further,
jinit_c_master_control() now resets all fields in the master struct that
are not related to the extension parameters.
This eliminates JBOOLEAN_USE_MOZ_DEFAULTS and replaces it with
JINT_COMPRESS_PROFILE, a more flexible and descriptive parameter. Currently,
this new parameter works in much the same way as the old-- it changes the
behavior of jpeg_set_defaults(). It currently supports only two values
(max. compression, i.e. mozjpeg defaults, and fastest, i.e. libjpeg-turbo
defaults), but it can be extended in the future with additional profiles that
balance compression ratio with performance.
Since mozjpeg is now backward ABI-compatible with libjpeg[-turbo], it is now
possible to temporarily load mozjpeg into a binary application and cause that
application to generate uber-compressed JPEGs (at the expense of an extreme
performance loss, of course.) For instance, someone could do
LD_LIBRARY_PATH=/opt/mozjpeg/lib convert blah_blah_blah
to make ImageMagick use mozjpeg instead of the system's pre-installed JPEG
library (libjpeg-turbo, in most cases.) However, this only makes sense if
mozjpeg is actually producing different behavior by default than libjpeg-turbo.
Currently it isn't. Currently it requires the application to set
JBOOLEAN_USE_MOZ_DEFAULTS to TRUE in order to enable the mozjpeg-specific
behavior, but of course applications that were built to use libjpeg[-turbo]
won't do that. Thus, this patch sets use_moz_defaults to TRUE by default,
requiring an application to explicitly set it to FALSE in order to revert to
the libjpeg[-turbo] behavior (makes sense, since the only applications that
would need to revert to the libjpeg[-turbo] behavior would be mozjpeg-aware
applications.)
Note that we discussed the possibility of adding a function
(jpeg_revert_defaults()), which would act the same as jpeg_set_defaults() does
in libjpeg[-turbo]. This is a good solution for implementing the -revert
switch in cjpeg, but unfortunately it doesn't work for jpegtran. The reason
is that jpeg_set_defaults() is called within the body of
jpeg_copy_critical_parameters(), which is part of the API. So yet again,
if mozjpeg were loaded into a non-mozjpeg-aware application at run time, it
would be desirable for jpeg_copy_critical_parameters() to set the parameters
to mozjpeg defaults. That means that, in order to implement the -revert
switch in jpegtran, it would be necessary to introduce a new function
(jpeg_revert_critical_parameters(), perhaps). It seems cleaner to just keep
using the JBOOLEAN_USE_MOZ_DEFAULTS parameter to control the behavior of
jpeg_set_defaults(), even though this represents a minor abuse of the libjpeg
API (jpeg_set_defaults() is technically supposed to set all of the parameters
to defaults, irrespective of any previous state. However, as long as we
document that JBOOLEAN_USE_MOZ_DEFAULTS works differently, then it should be
OK.)
