It also works on E2K as it supports these intrinsics.
On x86-64 runtime detection is used so the code keeps working on
older processors too. A CLMUL-only build can be done by using
-msse4.1 -mpclmul in CFLAGS and this will reduce the library
size since the generic implementation and its 8 KiB lookup table
will be omitted.
On 32-bit x86 this isn't used by default for now because by default
on 32-bit x86 the separate assembly file crc64_x86.S is used.
If --disable-assembler is used then this new CLMUL code is used
the same way as on 64-bit x86. However, a CLMUL-only build
(-msse4.1 -mpclmul) won't omit the 8 KiB lookup table on
32-bit x86 due to a currently-missing check for disabled
assembler usage.
The configure.ac check should be such that the code won't be
built if something in the toolchain doesn't support it but
--disable-clmul-crc option can be used to unconditionally
disable this feature.
CLMUL speeds up decompression of files that have compressed very
well (assuming CRC64 is used as a check type). It is know that
the CLMUL code is significantly slower than the generic code for
tiny inputs (especially 1-8 bytes but up to 16 bytes). If that
is a real-world problem then there is already a commented-out
variant that uses the generic version for small inputs.
Thanks to Ilya Kurdyukov for the original patch which was
derived from a white paper from Intel [1] (published in 2009)
and public domain code from [2] (released in 2016).
[1] https://www.intel.com/content/dam/www/public/us/en/documents/white-papers/fast-crc-computation-generic-polynomials-pclmulqdq-paper.pdf
[2] https://github.com/rawrunprotected/crc
It didn't do anything. There are only 32-bit x86 assembly files
and it feels likely that new files won't be added as intrinsics
in C are more portable across toolchains and OSes.
This uses it for CRC table initializations when using --disable-small.
It avoids mythread_once() overhead. It also means that then
--disable-small --disable-threads is thread-safe if this attribute
is supported.
__SSE2__ is the correct macro for SSE2 support with GCC, Clang,
and ICC. __SSE2_MATH__ means doing floating point math with SSE2
instead of 387. Often the latter macro is defined if the first
one is but it was still a bug.
In practice this means making the scripts work when
the input files have an unsupported check type which
isn't a problem in practice unless support for
some check types has been disabled at build time.
That's how it is preferred at the Translation Project.
On my system /usr/share/man/fr_FR doesn't contain any
other man pages than XZ Utils while /usr/share/man/fr
has quite a few, so this will fix that too.
Thanks to Benno Schulenberg from the Translation Project.
Modern 32-bit ARM in big endian mode use little endian for
instruction encoding still, so the filters work on such
executables too. It's likely less confusing for users this way.
The --arm64 option hasn't been implemented yet (there is
--experimental-arm64 but it's different). The --arm64 option
is added now anyway because this is the likely result and the
strings need to be ready for translators.
Thanks to Jia Tan.
If configured with --disable-lzip-decoder then --long-help will
still list `lzip' in --format but I left it like that since
due to translations it would be messy to have two help strings.
Features are disabled only in special situations so wrong help
in such a situation shouldn't matter much.
Thanks to Michał Górny for the original patch.
Support for format version 0 was removed from lzip 1.18 for some
reason. .lz format version 0 files are rare (and old) but some
source packages were released in this format, and some people might
have personal files in this format too. It's very little extra code
to support it along side format version 1 so this commits adds
support for both.
The Sync Flush marker extentension to the original .lz format
version 1 isn't supported. It would require changes to the
LZMA decoder itself. Such files are very rare anyway.
See the API doc for lzma_lzip_decoder() for more details about
the .lz format support.
Thanks to Michał Górny for the original patch.
"xz -v < regular_file > out.xz" doesn't display the percentage
and estimated remaining time because it doesn't even try to
check the input file size when input is read from stdin.
This could be improved but for now there's just a comment
to remind about it.
It worked for one input file since the counters are zero when
xz starts but they weren't reset when starting a new file in
passthru mode. For example, if files A, B, and C are one byte each,
then "xz -dcvf A B C" would show file sizes as 1, 2, and 3 bytes
instead of 1, 1, and 1 byte.
This affects lzma_memusage() and lzma_memlimit_set() when used
with the threaded decompressor. Now all allocations are reported
by lzma_memusage() (so it's not misleading) and lzma_memlimit_set()
cannot lower the limit below that value.
The alternative would have been to allow lowering the limit if
doing so is possible by freeing the cached memory but since
the primary use case of lzma_memlimit_set() is to increase
memlimit after LZMA_MEMLIMIT_ERROR this simple approach
was selected.
The cached memory was always included when enforcing
the memory usage limit while decoding.
Thanks to Jia Tan.
Don't call InitOnceComplete() if initialization was already done.
So far mythread_once() has been needed only when building
with --enable-small. windows/build.bash does this together
with --disable-threads so the Vista-specific mythread_once()
is never needed by those builds. VS project files or
CMake-builds don't support HAVE_SMALL builds at all.
Lasse Collin
Jia Tan