It's used only for basic bittrees and fixed-size reverse bittree
because those showed a clear benefit on x86-64 with GCC and Clang.
The other methods were more mixed and thus are commented out but
they should be tested on other archs.
Now extra buffer space is reserved so that repeating bytes for
any single match will never need to copy from two places (both
the beginning and the end of the buffer). This simplifies
dict_repeat() and helps a little with speed.
This seems to reduce .lzma decompression time about 2 %, so
with .xz and CRC it could be slightly less. The small things
add up still.
It's not completely obvious if this is better in the decoder.
It should be good if compiler can avoid creating a branch
(like using CMOV on x86).
This also makes lzma_encoder.c use the new macros.
The new decoder resumes the first decoder loop in the Resumable mode.
Then, the code executes in Non-resumable mode until it detects that it
cannot guarantee to have enough input/output to decode another symbol.
The Resumable mode is how the decoder has always worked. Before decoding
every input bit, it checks if there is enough space and will save its
location to be resumed later. When the decoder has more input/output,
it jumps back to the correct sequence in the Resumable mode code.
When the input/output buffers are large, the Resumable mode is much
slower than the Non-resumable because it has more branches and is harder
for the compiler to optimize since it is in a large switch block.
Early benchmarking shows significant time improvement (8-10% on gcc and
clang x86) by using the Non-resumable code as much as possible.
The new "safe" range decoder mode is the same as old range decoder, but
now the default behavior of the range decoder will not check if there is
enough input or output to complete the operation. When the buffers are
close to fully consumed, the "safe" operations must be used instead. This
will improve speed because it will reduce the number of branches needed
for most of the range decoder operations.
The footer template from Doxygen has the closing </body> </html>
as Doxygen doesn't add them otherwise.
target="_blank" was omitted as it's not useful here but
it can be slightly annoying as one cannot just go back
in the browser history.
Since the footer links to the license file in the same
directory and not to CC website, the rel attributes
can be omitted.
lzmainfo has had translation support since 2009 at least but
it was never added to po/POTFILES.in so the messages weren't
translated. It's a very rarely needed tool so it's not too bad.
This also adds src/xz/mytime.c to po/POTFILES.in although there
are no translatable strings. It's simpler this way so that it
won't be forgotten if strings were ever added to that file.
The main reason is a kind of silly one:
xz-man.pot contains strings from all man pages in XZ Utils.
The man pages of xzdiff, xzgrep, and xzmore were under GPLv2
and the rest under 0BSD. Thus xz-man.pot contained strings
under two licences. po4a creates the translated man pages
from the combined 0BSD+GPLv2 xz-man.pot.
I haven't liked this mixing in xz-man.pot but the
Translation Project requires that all man pages must be
in the same .pot file. So a separate xz-man-gpl.pot
wasn't an option.
Since these man pages are short, rewriting them was quick enough.
Now xz-man.pot is entirely under 0BSD and marking the per-file
licenses is simpler.
As a bonus, some wording hopefully is now slightly better
although it's perhaps a matter of taste.
NOTE: In xzgrep.1, the EXIT STATUS section was written by me
in the commit d796b6d7fd so that's
why that section could be taken as is from the old xzgrep.1.
Perhaps the generated files aren't even copyrightable but
using the same license for them as for the rest of the liblzma
keeps things more consistent for tools that look for license info.
The initial commit 5d018dc035
in 2007 had a comment in sha256.c that the code is based on
Crypto++ Library 5.5.1. In 2009 the Authors list in sha256.c
and the AUTHORS file was updated with information that the
code had come from Crypto++ but via 7-Zip. I know I had viewed
7-Zip's SHA-256 code but back then the C code has been identical
enough with Crypto++, so I don't why I thought the author info
would need that extra step via 7-Zip for this single file.
Another error is that I had mixed sha.* and shacal2.* files
when checking for author info in Crypto++. The shacal2.* files
aren't related to liblzma's sha256.c and thus Kevin Springle's
code in Crypto++ isn't either.
Jia Tan
Lasse Collin