107 lines
3.1 KiB
C
107 lines
3.1 KiB
C
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/* -*- mode: c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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pmurhashAPI.h -- interface file for external clients
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Copyright (C) 2014 Wush Wu and Dirk Eddelbuettel
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This file is part of digest.
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digest is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 2 of the License, or
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(at your option) any later version.
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digest is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with digest. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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Purpose:
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Provide MurmurHash3A for use by C / C++ code of other R packages
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Usage:
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1) In your package, add 'LinkingTo: digest' to the DESCRIPTION file.
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This ensure that R will know the path to this file.
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2) In your source code, add '#include <pmurhashAPI.h>'
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This ensures the compiler knows the declaration of the function
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interface.
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3) In your package's source code, call 'res = PMurHash32(seed,
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key, len);' where res and seed are of type MH_UINT32 (which
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is defined appropriately below).
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4) The local function here sets a static pointer to the actual
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MurmurHash32 implementation in this package. R takes care of
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the function registration, export and import --- meaning that
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no build-time linking of your package is needed resulting in
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simpler and more robust build steps.
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*/
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#ifndef __PMURHASH_H__
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#define __PMURHASH_H__
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#include <stddef.h>
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#include <R_ext/Rdynload.h>
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#ifdef HAVE_VISIBILITY_ATTRIBUTE
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# define attribute_hidden __attribute__ ((visibility ("hidden")))
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#else
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# define attribute_hidden
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* First look for special cases */
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#if defined(_MSC_VER)
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#define MH_UINT32 unsigned long
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#endif
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/* If the compiler says it's C99 then take its word for it */
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#if !defined(MH_UINT32) && ( \
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defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L )
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#include <stdint.h>
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#define MH_UINT32 uint32_t
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#endif
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/* Otherwise try testing against max value macros from limit.h */
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#if !defined(MH_UINT32)
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#include <limits.h>
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#if (USHRT_MAX == 0xffffffffUL)
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#define MH_UINT32 unsigned short
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#elif (UINT_MAX == 0xffffffffUL)
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#define MH_UINT32 unsigned int
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#elif (ULONG_MAX == 0xffffffffUL)
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#define MH_UINT32 unsigned long
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#endif
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#endif
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#if !defined(MH_UINT32)
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#error Unable to determine type name for unsigned 32-bit int
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#endif
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MH_UINT32 attribute_hidden PMurHash32(MH_UINT32 seed, const void *key, int len) {
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static MH_UINT32(*f)(MH_UINT32, const void*, int) = NULL;
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if (!f) {
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f = (MH_UINT32(*)(MH_UINT32, const void*, int)) R_GetCCallable("digest", "PMurHash32");
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}
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return f(seed, key, len);
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}
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#ifdef __cplusplus
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}
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#endif
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#endif /* __PMURHASH_H__ */
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