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c2f81b6d
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2025-09-25T16:34:20
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AltiVec: Fix -Wshadow warnings
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4e151a4a
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2025-08-26T21:11:07
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Remove vestigial filenames from SIMD code headers
These were a relic of libjpeg/SIMD, which attempted to follow the
conventions of the libjpeg source code, but they are no longer relevant
(or even accurate in some cases.)
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602f0592
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2024-12-12T00:09:34
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AltiVec: Disable/Fix some strict compiler warnings
We use a standard set of strict compiler warnings with Clang and GCC to
continuously test and maintain C89 conformance in the libjpeg API code.
However, SIMD extensions need not comply with that. The AltiVec code
specifically uses some C99isms, so disable -Wc99-extensions and
-Wpedantic in the scope of that code. Also disable -Wshadow, because
I'm too lazy to fix the TRANSPOSE() macro. Also
use #ifdef __BIG_ENDIAN__ and #if defined(__BIG_ENDIAN__) instead
of #if __BIG_ENDIAN__
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e69dd40c
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2024-01-23T13:26:41
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Reorganize source to make things easier to find
- Move all libjpeg documentation, except for README.ijg, into the doc/
subdirectory.
- Move the TurboJPEG C API documentation from doc/html/ into
doc/turbojpeg/.
- Move all C source code and headers into a src/ subdirectory.
- Move turbojpeg-jni.c into the java/ subdirectory.
Referring to #226, there is no ideal solution to this problem. A
semantically ideal solution would have involved placing all source code,
including the SIMD and Java source code, under src/ (or perhaps placing
C library source code under lib/ and C test program source code under
test/), all header files under include/, and all documentation under
doc/. However:
- To me it makes more sense to have separate top-level directories for
each language, since the SIMD extensions and the Java API are
technically optional features. src/ now contains only the code that
is relevant to the core C API libraries and associated programs.
- I didn't want to bury the java/ and simd/ directories or add a level
of depth to them, since both directories already contain source code
that is 3-4 levels deep.
- I would prefer not to separate the header files from the C source
code, because:
1. It would be disruptive. libjpeg and libjpeg-turbo have
historically placed C source code and headers in the same
directory, and people who are familiar with both projects (self
included) are used to looking for the headers in the same directory
as the C source code.
2. In terms of how the headers are used internally in libjpeg-turbo,
the distinction between public and private headers is a bit fuzzy.
- It didn't make sense to separate the test source code from the library
source code, since there is not a clear distinction in some cases.
(For instance, the IJG image I/O functions are used by cjpeg and djpeg
as well as by the TurboJPEG API.)
This solution is minimally disruptive, since it keeps all C source code
and headers together and keeps java/ and simd/ as top-level directories.
It is a bit awkward, because java/ and simd/ technically contain source
code, even though they are not under src/. However, other solutions
would have been more awkward for different reasons.
Closes #226
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78a36f6d
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2022-11-15T17:01:17
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Fix buffer overrun in 12-bit prog Huffman encoder
Regression introduced by 16bd984557fa2c490be0b9665e2ea0d4274528a8 and
5b177b3cab5cfb661256c1e74df160158ec6c34e
The pre-computed absolute values used in encode_mcu_AC_first() and
encode_mcu_AC_refine() were stored in a JCOEF (signed short) array.
When attempting to losslessly transform a specially-crafted malformed
12-bit JPEG image with a coefficient value of -32768 into a progressive
12-bit JPEG image, the progressive Huffman encoder attempted to store
the absolute value of -32768 in the JCOEF array, thus overflowing the
16-bit signed data type. Therefore, at this point in the code:
https://github.com/libjpeg-turbo/libjpeg-turbo/blob/8c5e78ce292c1642057102eac42f12ab57964293/jcphuff.c#L889
the absolute value was read as -32768, which caused the test at
https://github.com/libjpeg-turbo/libjpeg-turbo/blob/8c5e78ce292c1642057102eac42f12ab57964293/jcphuff.c#L896
to fail, falling through to
https://github.com/libjpeg-turbo/libjpeg-turbo/blob/8c5e78ce292c1642057102eac42f12ab57964293/jcphuff.c#L908
with an overly large value of r (46) that, when shifted left four
places, incremented, and passed to emit_symbol(), exceeded the maximum
index (255) for the derived code tables. Fortunately, the buffer
overrun was fully contained within phuff_entropy_encoder, so the issue
did not generate a segfault or other user-visible errant behavior, but
it did cause a UBSan failure that was detected by OSS-Fuzz.
This commit introduces an unsigned JCOEF (UJCOEF) data type and uses it
to store the absolute values of DCT coefficients computed by the
AC_first_prepare() and AC_refine_prepare() methods.
Note that the changes to the Arm Neon progressive Huffman encoder
extensions cause signed 16-bit instructions to be replaced with
equivalent unsigned 16-bit instructions, so the changes should be
performance-neutral.
Based on:
https://github.com/mayeut/libjpeg-turbo/commit/bbf61c0382c4f8bd1f1cfc666467581496c2fb7c
Closes #628
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f579cc11
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2022-10-03T19:46:09
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Make SIMD capability variables thread-local ...
... on platforms that support TLS, which should include all
currently-supported platforms
(https://libjpeg-turbo.org/Documentation/OfficialBinaries)
Addresses a concern raised in #87
Although it is still my opinion that the data race in init_simd() was
innocuous, we can now fix it for free thanks to
ae87a958613b69628b92088b313ded0d4f59a716, so why not?
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59337a67
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2022-07-06T12:11:50
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PowerPC: Detect AltiVec support on OS X
libjpeg-turbo's AltiVec SIMD extensions previously assumed that AltiVec
instructions were available on all Power Macs that supported OS X 10.4
"Tiger" (the earliest version of OS X that libjpeg-turbo has ever
supported), but Tiger can actually run on PowerPC G3 processors, which
lack AltiVec instructions. This commit enables run-time detection of
AltiVec instructions on OS X/PowerPC systems if AltiVec instructions are
not force-enabled at compile time (using -maltivec). This allows the
same build of libjpeg-turbo to support G3, G4, and G5 Power Macs.
Closes #609
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9abeff46
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2022-03-09T11:48:30
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Remove extraneous #include directives
jinclude.h already includes stdio.h, stdlib.h, and string.h.
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d401d625
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2021-10-27T03:39:09
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PowerPC: Detect AltiVec support on FreeBSD
Recent FreeBSD/PowerPC compilers, such as Clang 11.0.x on FreeBSD 13, do
the equivalent of passing -maltivec to the compiler by default, so
run-time AltiVec detection is unnecessary. However, it becomes
necessary when using other compilers or when passing -mno-altivec to the
compiler.
Closes #552
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7c1a1789
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2020-11-05T16:04:55
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Merge branch 'master' into dev
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6e632af9
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2020-11-04T10:13:06
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Demote "fast" [I]DCT algorithms to legacy status
- Refer to the "slow" [I]DCT algorithms as "accurate" instead, since
they are not slow under libjpeg-turbo.
- Adjust documentation claims to reflect the fact that the "slow" and
"fast" algorithms produce about the same performance on AVX2-equipped
CPUs (because of the dual-lane nature of AVX2, it was not possible to
accelerate the "fast" algorithm beyond what was achievable with SSE2.)
Also adjust the claims to reflect the fact that the "fast" algorithm
tends to be ~5-15% faster than the "slow" algorithm on
non-AVX2-equipped CPUs, regardless of the use of the libjpeg-turbo
SIMD extensions.
- Indicate the legacy status of the "fast" and float algorithms in the
documentation and cjpeg/djpeg usage info.
- Remove obsolete paragraph in the djpeg man page that suggested that
the float algorithm could be faster than the "fast" algorithm on some
CPUs.
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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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7b3c0f01
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2018-03-31T13:25:44
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PowerPC: Fix comp. warning when built w/ -maltivec
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5b177b3c
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2018-03-22T11:36:43
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C/SSE2 optimization of encode_mcu_AC_first()
This commit adds C and SSE2 optimizations for the encode_mcu_AC_first()
function used in progressive Huffman encoding.
The image used for testing can be retrieved from this page:
https://blog.cloudflare.com/doubling-the-speed-of-jpegtran
All timings done on `Intel(R) Core(TM) i7-4870HQ CPU @ 2.50GHz`
clang version is `Apple LLVM version 9.0.0 (clang-900.0.39.2)`
gcc-5 version is `gcc-5 (Homebrew GCC 5.5.0) 5.5.0`
gcc-7 version is `gcc-7 (Homebrew GCC 7.2.0) 7.2.0`
Here are the results in comparison to libjpeg-turbo@293263c using
`time ./jpegtran -outfile /dev/null -progressive -optimise -copy none print_poster_0025.jpg`
C
clang x86_64: +19%
gcc-5 x86_64: +80%
gcc-7 x86_64: +57%
clang i386: +5%
gcc-5 i386: +59%
gcc-7 i386: +51%
SSE2
clang x86_64: +79%
gcc-5 x86_64: +158%
gcc-7 x86_64: +122%
clang i386: +71%
gcc-5 i386: +134%
gcc-7 i386: +135%
Discussion in libjpeg-turbo/libjpeg-turbo#46
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16bd9845
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2018-03-02T22:33:19
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C/SSE2 optimization of encode_mcu_AC_refine()
This commit adds C and SSE2 optimizations for the encode_mcu_AC_refine()
function used in progressive Huffman encoding.
The image used for testing can be retrieved from this page:
https://blog.cloudflare.com/doubling-the-speed-of-jpegtran
All timings done on `Intel(R) Core(TM) i7-4870HQ CPU @ 2.50GHz`
clang version is `Apple LLVM version 9.0.0 (clang-900.0.39.2)`
gcc-5 version is `gcc-5 (Homebrew GCC 5.5.0) 5.5.0`
gcc-7 version is `gcc-7 (Homebrew GCC 7.2.0) 7.2.0`
Here are the results in comparison to libjpeg-turbo@3c54642 using
`time ./jpegtran -outfile /dev/null -progressive -optimise -copy none print_poster_0025.jpg`
C
clang x86_64: +7%
gcc-5 x86_64: +30%
gcc-7 x86_64: +33%
clang i386: +0%
gcc-5 i386: +24%
gcc-7 i386: +23%
SSE2
clang x86_64: +42%
gcc-5 x86_64: +53%
gcc-7 x86_64: +64%
clang i386: +35%
gcc-5 i386: +46%
gcc-7 i386: +49%
Discussion in libjpeg-turbo/libjpeg-turbo#46
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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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84fbd4f1
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2018-03-17T00:27:49
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Merge branch 'master' into dev
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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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35ed3c97
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2018-02-28T16:24:03
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SIMD: Formatting tweaks + remove unnecessary code
+ "JSIMD_ARM_NEON" = "JSIMD_NEON"
+ "JSIMD_MIPS_DSPR2" = "JSIMD_DSPR2"
+ "*_mips_dspr2" = "*_dspr2"
It's obvious that "NEON" refers to Arm and "DSPr2" refers to MIPS, and
this naming convention is consistent with the other SIMD extensions.
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8a9b042b
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2016-12-10T09:35:30
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Merge branch 'master' into dev
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6abd3916
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2016-11-15T08:47:43
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Unified CMake-based build system
See #56 for discussion.
Fixes #21, Fixes #29, Fixes #37, Closes #56, Fixes #58, Closes #73
Obviates #82
See also:
https://sourceforge.net/p/libjpeg-turbo/feature-requests/5/
https://sourceforge.net/p/libjpeg-turbo/patches/5/
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