view contrib/python-zstandard/zstd/dictBuilder/divsufsort.h @ 30434:2e484bdea8c4

zstd: vendor zstd 1.1.1

zstd is a new compression format and it is awesome, yielding
higher compression ratios and significantly faster compression
and decompression operations compared to zlib (our current
compression engine of choice) across the board.

We want zstd to be a 1st class citizen in Mercurial and to eventually
be the preferred compression format for various operations.

This patch starts the formal process of supporting zstd by vendoring
a copy of zstd. Why do we need to vendor zstd? Good question.

First, zstd is relatively new and not widely available yet. If we
didn't vendor zstd or distribute it with Mercurial, most users likely
wouldn't have zstd installed or even available to install. What good
is a feature if you can't use it? Vendoring and distributing the zstd
sources gives us the highest liklihood that zstd will be available to
Mercurial installs.

Second, the Python bindings to zstd (which will be vendored in a
separate changeset) make use of zstd APIs that are only available
via static linking. One reason they are only available via static
linking is that they are unstable and could change at any time.
While it might be possible for the Python bindings to attempt to
talk to different versions of the zstd C library, the safest thing to
do is link against a specific, known-working version of zstd. This
is why the Python zstd bindings themselves vendor zstd and why we
must as well. This also explains why the added files are in a
"python-zstandard" directory.

The added files are from the 1.1.1 release of zstd (Git commit
4c0b44f8ced84c4c8edfa07b564d31e4fa3e8885 from
https://github.com/facebook/zstd) and are added without modifications.
Not all files from the zstd "distribution" have been added. Notably
missing are files to support interacting with "legacy," pre-1.0
versions of zstd. The decision of which files to include is made by
the upstream python-zstandard project (which I'm the author of). The
files in this commit are a snapshot of the files from the 0.5.0
release of that project, Git commit
e637c1b214d5f869cf8116c550dcae23ec13b677 from
https://github.com/indygreg/python-zstandard.

/*
 * divsufsort.h for libdivsufsort-lite
 * Copyright (c) 2003-2008 Yuta Mori All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

#ifndef _DIVSUFSORT_H
#define _DIVSUFSORT_H 1

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */


/*- Prototypes -*/

/**
 * Constructs the suffix array of a given string.
 * @param T [0..n-1] The input string.
 * @param SA [0..n-1] The output array of suffixes.
 * @param n The length of the given string.
 * @param openMP enables OpenMP optimization.
 * @return 0 if no error occurred, -1 or -2 otherwise.
 */
int
divsufsort(const unsigned char *T, int *SA, int n, int openMP);

/**
 * Constructs the burrows-wheeler transformed string of a given string.
 * @param T [0..n-1] The input string.
 * @param U [0..n-1] The output string. (can be T)
 * @param A [0..n-1] The temporary array. (can be NULL)
 * @param n The length of the given string.
 * @param num_indexes The length of secondary indexes array. (can be NULL)
 * @param indexes The secondary indexes array. (can be NULL)
 * @param openMP enables OpenMP optimization.
 * @return The primary index if no error occurred, -1 or -2 otherwise.
 */
int
divbwt(const unsigned char *T, unsigned char *U, int *A, int n, unsigned char * num_indexes, int * indexes, int openMP);


#ifdef __cplusplus
} /* extern "C" */
#endif /* __cplusplus */

#endif /* _DIVSUFSORT_H */