path: root/ewah/ewah_rlw.c
AgeCommit message (Collapse)Author
2018-06-21ewah: delete unused 'rlwit_discharge_empty()'Junio C Hamano
Complete the removal of unused 'ewah bitmap' code by removing the now unused 'rlwit_discharge_empty()' function. Also, the 'ewah_clear()' function can now be made a file-scope static symbol. Signed-off-by: Ramsay Jones <> Signed-off-by: Junio C Hamano <>
2017-11-09Replace Free Software Foundation address in license noticesTodd Zullinger
The mailing address for the FSF has changed over the years. Rather than updating the address across all files, refer readers to, 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 <> Signed-off-by: Junio C Hamano <>
2013-12-30ewah: compressed bitmap implementationVicent Marti
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: The original Java implementation can also be found on GitHub: [jc: stripped debug-only code per Peff's $gmane/239768] Signed-off-by: Vicent Marti <> Signed-off-by: Jeff King <> Helped-by: Ramsay Jones <> Signed-off-by: Junio C Hamano <>