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bf01ed2f
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2022-11-04T13:08:08
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Fix build when SIMD extensions are disabled
(Broken by previous commit)
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e8b40f3c
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2022-11-01T21:45:39
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Vastly improve 12-bit JPEG integration
The Gordian knot that 7fec5074f962b20ed00b4f5da4533e1e8d4ed8ac attempted
to unravel was caused by the fact that there are several
data-precision-dependent (JSAMPLE-dependent) fields and methods in the
exposed libjpeg API structures, and if you change the exposed libjpeg
API structures, then you have to change the whole API. If you change
the whole API, then you have to provide a whole new library to support
the new API, and that makes it difficult to support multiple data
precisions in the same application. (It is not impossible, as example.c
demonstrated, but using data-precision-dependent libjpeg API structures
would have made the cjpeg, djpeg, and jpegtran source code hard to read,
so it made more sense to build, install, and package 12-bit-specific
versions of those applications.)
Unfortunately, the result of that initial integration effort was an
unreadable and unmaintainable mess, which is a problem for a library
that is an ISO/ITU-T reference implementation. Also, as I dug into the
problem of lossless JPEG support, I realized that 16-bit lossless JPEG
images are a thing, and supporting yet another version of the libjpeg
API just for those images is untenable.
In fact, however, the touch points for JSAMPLE in the exposed libjpeg
API structures are minimal:
- The colormap and sample_range_limit fields in jpeg_decompress_struct
- The alloc_sarray() and access_virt_sarray() methods in
jpeg_memory_mgr
- jpeg_write_scanlines() and jpeg_write_raw_data()
- jpeg_read_scanlines() and jpeg_read_raw_data()
- jpeg_skip_scanlines() and jpeg_crop_scanline()
(This is subtle, but both of those functions use JSAMPLE-dependent
opaque structures behind the scenes.)
It is much more readable and maintainable to provide 12-bit-specific
versions of those six top-level API functions and to document that the
aforementioned methods and fields must be type-cast when using 12-bit
samples. Since that eliminates the need to provide a 12-bit-specific
version of the exposed libjpeg API structures, we can:
- Compile only the precision-dependent libjpeg modules (the
coefficient buffer controllers, the colorspace converters, the
DCT/IDCT managers, the main buffer controllers, the preprocessing
and postprocessing controller, the downsampler and upsamplers, the
quantizers, the integer DCT methods, and the IDCT methods) for
multiple data precisions.
- Introduce 12-bit-specific methods into the various internal
structures defined in jpegint.h.
- Create precision-independent data type, macro, method, field, and
function names that are prefixed by an underscore, and use an
internal header to convert those into precision-dependent data
type, macro, method, field, and function names, based on the value
of BITS_IN_JSAMPLE, when compiling the precision-dependent libjpeg
modules.
- Expose precision-dependent jinit*() functions for each of the
precision-dependent libjpeg modules.
- Abstract the precision-dependent libjpeg modules by calling the
appropriate precision-dependent jinit*() function, based on the
value of cinfo->data_precision, from top-level libjpeg API
functions.
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7fec5074
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2022-03-08T12:34:11
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Support 8-bit & 12-bit JPEGs using the same build
Partially implements #199
This commit also implements a request from #178 (the ability to compile
the libjpeg example as a standalone program.)
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01e30323
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2019-01-23T14:58:24
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Eliminate support for compilers w/o unsigned char
libjpeg-turbo has never really supported such compilers, since (AFAIK)
they are non-existent on any modern computing platform and thus
impossible for us to test. (Also, the TurboJPEG API would break without
unsigned chars.)
Furthermore, the unified CMake-based build system introduced in 2.0
always defines HAVE_UNSIGNED_CHAR, so retaining other code paths is
pointless. Eliminating support for compilers without unsigned char
eliminates the need for the GETJSAMPLE() macro, which improves the
readability of many parts of the code as well as improving the
performance of writing Targa and Windows BMP files.
Fixes #317
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293263c3
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2018-03-17T15:14:35
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Format preprocessor macros more consistently
Within the libjpeg API code, it seems to be more the convention than not
to separate the macro name and value by two or more spaces, which
improves general readability. Making this consistent across all of
libjpeg-turbo is less about my individual preferences and more about
making it easy to automatically detect variations from our chosen
formatting convention. I intend to release the script I'm using to
validate this stuff, once it matures and stabilizes a bit.
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19c791cd
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2018-03-08T10:55:20
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Improve code formatting consistency
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.
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9d9d8fe6
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2017-11-17T18:15:42
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Code formatting tweaks
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e621dfc5
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2016-02-19T10:35:09
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More minor code formatting tweaks
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bd49803f
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2016-02-19T08:53:33
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Use consistent/modern code formatting for pointers
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.
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fc11193e
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2014-01-19T00:00:00
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The Independent JPEG Group's JPEG software v9a
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3ee3d879
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2016-02-04T10:58:10
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Fix Visual C++ compiler warnings
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aa769feb
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2015-10-15T02:25:00
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Fix compiler warnings under Visual C++
A few of these are long-standing, but most were exposed when switching
from INT32 to JLONG.
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d65e768b
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2015-10-14T22:26:25
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Fix additional issues reported by UB sanitizers
Most of these involved overrunning the signed 32-bit JLONG type whenever
building libjpeg-turbo with a 32-bit compiler. These issues are not
believed to represent actual security threats, but eliminating them
makes it easier to detect such threats should they arise in the future.
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1e32fe31
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2015-10-14T17:32:39
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Replace INT32 with a new internal datatype (JLONG)
These days, INT32 is a commonly-defined datatype in system headers. We
cannot eliminate the definition of that datatype from jmorecfg.h, since
the INT32 typedef has technically been part of the libjpeg API since
version 5 (1994.) However, using INT32 internally is risky, because the
inclusion of a particular header (Xmd.h, for instance) could change the
definition of INT32 from long to int on 64-bit platforms and thus change
the internal behavior of libjpeg-turbo in unexpected ways (for instance,
failing to correctly set __INT32_IS_ACTUALLY_LONG to match the INT32
typedef-- perhaps as a result of including the wrong version of
jpeglib.h-- could cause libjpeg-turbo to produce incorrect results.)
The library has always been built in environments in which INT32 is
effectively long (on Windows, long is always 32-bit, so effectively it's
the same as int), so it makes sense to turn INT32 into an explicitly
long datatype. This ensures that libjpeg-turbo will always behave
consistently, regardless of the headers included at compile time.
Addresses a concern expressed in #26.
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7e3acc0e
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2015-10-10T10:25:46
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Rename README, LICENSE, BUILDING text files
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.
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b5a55e6d
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2015-08-29T18:05:43
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Fix negative shift with IFAST FDCT and qual=100
With certain images, compressing using quality=100 and the fast integer
forward DCT will cause the divisor passed to compute_reciprocal() to be
1. In those cases, the library already disables the SIMD quantization
algorithm to avoid 16-bit overflow. However, compute_reciprocal()
doesn't properly handle the divisor==1 case, so we need to use special
values in that case so that the C quantization algorithm will behave
like an identity function.
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a2e6a9dd
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2006-02-04T00:00:00
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IJG R6b with x86SIMD V1.02
Independent JPEG Group's JPEG software release 6b
with x86 SIMD extension for IJG JPEG library version 1.02
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489583f5
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1996-02-07T00:00:00
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The Independent JPEG Group's JPEG software v6a
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bc79e068
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1995-08-02T00:00:00
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The Independent JPEG Group's JPEG software v6
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36a4cccc
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1994-09-24T00:00:00
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The Independent JPEG Group's JPEG software v5
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5996a25e
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2009-06-27T00:00:00
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The Independent JPEG Group's JPEG software v7
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eca0637c
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2014-11-06T09:32:38
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Remove trailing spaces
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.4.x@1412 632fc199-4ca6-4c93-a231-07263d6284db
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aee4f721
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2014-08-09T23:06:07
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12-bit JPEG support
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1337 632fc199-4ca6-4c93-a231-07263d6284db
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5de454b2
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2014-05-18T19:04:03
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libjpeg-turbo has never supported non-ANSI compilers, so get rid of the crufty SIZEOF() macro. It was not being used consistently anyhow, so it would not have been possible to build prior releases of libjpeg-turbo using the broken compilers for which that macro was designed.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1313 632fc199-4ca6-4c93-a231-07263d6284db
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bc56b754
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2014-05-16T10:43:44
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Get rid of the HAVE_PROTOTYPES configuration option, as well as the related JMETHOD and JPP macros. libjpeg-turbo has never supported compilers that don't handle prototypes. Doing so requires ansi2knr, which isn't even supported in the IJG code anymore.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1308 632fc199-4ca6-4c93-a231-07263d6284db
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b7753510
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2014-05-11T09:36:25
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Convert tabs to spaces in the libjpeg code and the SIMD code (TurboJPEG retains the use of tabs for historical reasons. They were annoying in the libjpeg code primarily because they were not consistently used and because they were used to format as well as indent the code. In the case of TurboJPEG, tabs are used just to indent the code, so even if the editor assumes a different tab width, the code will still be readable.)
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.3.x@1285 632fc199-4ca6-4c93-a231-07263d6284db
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e5eaf374
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2014-05-09T18:00:32
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Convert tabs to spaces in the libjpeg code and the SIMD code (TurboJPEG retains the use of tabs for historical reasons. They were annoying in the libjpeg code primarily because they were not consistently used and because they were used to format as well as indent the code. In the case of TurboJPEG, tabs are used just to indent the code, so even if the editor assumes a different tab width, the code will still be readable.)
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1278 632fc199-4ca6-4c93-a231-07263d6284db
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a6ef282a
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2013-09-28T03:23:49
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Some of the IJG headers say "Modified by", so clarify that our "Modifications" are not referring to these.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.3.x@1053 632fc199-4ca6-4c93-a231-07263d6284db
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a73e870a
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2012-12-31T02:52:30
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Change the copyright notices to make it clear that our modified files are not part of the IJG's software.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.2.x@873 632fc199-4ca6-4c93-a231-07263d6284db
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0f0fd751
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2012-02-07T23:27:14
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Compiler warnings
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.1.x@784 632fc199-4ca6-4c93-a231-07263d6284db
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d65d99a9
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2012-01-31T03:39:23
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Compiler warnings
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.2.x@758 632fc199-4ca6-4c93-a231-07263d6284db
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a49c4e52
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2011-02-18T20:50:08
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The SIMD quantization algorithm does not produce correct results with the fast forward integer DCT and JPEG qualities >= 98, so for now, use the non-SIMD quantization function under those circumstances.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@395 632fc199-4ca6-4c93-a231-07263d6284db
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6ca69537
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2011-02-18T03:31:11
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The SIMD quantization algorithm does not produce correct results with the fast forward integer DCT and JPEG qualities >= 98, so for now, use the non-SIMD quantization function under those circumstances.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.0.x@383 632fc199-4ca6-4c93-a231-07263d6284db
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72abc297
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2011-02-18T01:45:24
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The SIMD quantization algorithm does not produce correct results with the fast forward integer DCT and JPEG qualities >= 98, so for now, use the non-SIMD quantization function under those circumstances.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.1.x@378 632fc199-4ca6-4c93-a231-07263d6284db
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fc5dc4fa
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2009-10-01T22:26:14
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Some systems (notably OS X Leopard) have fls() already, so rename ours to avoid conflict
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@66 632fc199-4ca6-4c93-a231-07263d6284db
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dc5db14a
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2009-03-13T12:17:26
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Move variable init around a bit to please crappy compilers.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@26 632fc199-4ca6-4c93-a231-07263d6284db
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35c47196
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2009-03-09T13:29:37
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Make sure the work space memory is properly aligned
We use the heap allocators to avoid having more than one implementation
of the alignment logic.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@19 632fc199-4ca6-4c93-a231-07263d6284db
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dedc42e2
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2009-03-09T13:23:04
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"Optimise" quantization step by replacing the division by a multiplication.
This has no measurable difference right now but makes it possible to do
SIMD implementations of this stage.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@16 632fc199-4ca6-4c93-a231-07263d6284db
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59a3938b
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2009-03-09T13:15:56
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Framework for supporting SIMD acceleration
Designed to impose minimal changes on the "normal" code.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@14 632fc199-4ca6-4c93-a231-07263d6284db
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49dcbfbf
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2009-03-09T10:37:20
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Split up the forward DCT routine into three stages
Divide it into sample conversion, DCT and quantization in order to
easily provide alternative implementations of each stage.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@13 632fc199-4ca6-4c93-a231-07263d6284db
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