The mailing address for the FSF has changed over the years. Rather than
updating the address across all files, refer readers to gnu.org, as the
GNU GPL documentation now suggests for license notices. The mailing
address is retained in the full license files (COPYING and LGPL-2.1).
The old address is still present in t/diff-lib/COPYING. This is
intentional, as the file is used in tests and the contents are not
expected to change.
Signed-off-by: Todd Zullinger <tmz@pobox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This code was originally written with the idea that it could
be spun off into its own ewah library, and uses the
overrideable ewah_malloc to do allocations.
We plug in xmalloc as our ewah_malloc, of course. But over
the years the ewah code itself has become more entangled
with git, and the return value of many ewah_malloc sites is
not checked.
Let's just drop the level of indirection and use xmalloc and
friends directly. This saves a few lines, and will let us
adapt these sites to our more advanced malloc helpers.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The ewah/ewok.h header pollutes the global namespace with
"BITS_IN_WORD", without any specific notion that we are
talking about the bits in an eword_t. We can give this the
more specific name "BITS_IN_EWORD".
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The __builtin_ctzll function was added in gcc 3.4.0.
This extends the check for gcc so that use of __builtin_ctzll is only
enabled if gcc >= 3.4.0.
Signed-off-by: Tom G. Christensen <tgc@statsbiblioteket.dk>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
EWAH is a word-aligned compressed variant of a bitset (i.e. a data
structure that acts as a 0-indexed boolean array for many entries).
It uses a 64-bit run-length encoding (RLE) compression scheme,
trading some compression for better processing speed.
The goal of this word-aligned implementation is not to achieve
the best compression, but rather to improve query processing time.
As it stands right now, this EWAH implementation will always be more
efficient storage-wise than its uncompressed alternative.
EWAH arrays will be used as the on-disk format to store reachability
bitmaps for all objects in a repository while keeping reasonable sizes,
in the same way that JGit does.
This EWAH implementation is a mostly straightforward port of the
original `javaewah` library that JGit currently uses. The library is
self-contained and has been embedded whole (4 files) inside the `ewah`
folder to ease redistribution.
The library is re-licensed under the GPLv2 with the permission of Daniel
Lemire, the original author. The source code for the C version can
be found on GitHub:
https://github.com/vmg/libewok
The original Java implementation can also be found on GitHub:
https://github.com/lemire/javaewah
[jc: stripped debug-only code per Peff's $gmane/239768]
Signed-off-by: Vicent Marti <tanoku@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Helped-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
