mirror of https://gitee.com/bigwinds/arangodb
218 lines
7.9 KiB
C
218 lines
7.9 KiB
C
////////////////////////////////////////////////////////////////////////////////
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/// @brief mersenne twister implementation
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///
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/// @file
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///
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/// DISCLAIMER
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///
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/// Copyright 2004-2013 triAGENS GmbH, Cologne, Germany
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///
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/// Licensed under the Apache License, Version 2.0 (the "License");
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/// you may not use this file except in compliance with the License.
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/// You may obtain a copy of the License at
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///
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/// http://www.apache.org/licenses/LICENSE-2.0
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///
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/// Unless required by applicable law or agreed to in writing, software
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/// distributed under the License is distributed on an "AS IS" BASIS,
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/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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/// See the License for the specific language governing permissions and
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/// limitations under the License.
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///
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/// Copyright holder is triAGENS GmbH, Cologne, Germany
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///
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/// @author Jan Steemann
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/// @author see copyright notice of original authors below
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/// @author Copyright 2012-2013, triAGENS GmbH, Cologne, Germany
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////////////////////////////////////////////////////////////////////////////////
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#include "mersenne.h"
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#include "BasicsC/threads.h"
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// -----------------------------------------------------------------------------
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// --SECTION-- MERSENNE TWISTER
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// -----------------------------------------------------------------------------
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// -----------------------------------------------------------------------------
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// --SECTION-- static functions
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// -----------------------------------------------------------------------------
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////////////////////////////////////////////////////////////////////////////////
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/// @addtogroup Random
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/// @{
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////////////////////////////////////////////////////////////////////////////////
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/*
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A C-program for MT19937, with initialization improved 2002/1/26.
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Coded by Takuji Nishimura and Makoto Matsumoto.
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Before using, initialize the state by using init_genrand(seed)
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or init_by_array(init_key, key_length).
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Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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1. Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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3. The names of its contributors may not be used to endorse or promote
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products derived from this software without specific prior written
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permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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Any feedback is very welcome.
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http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
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email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
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*/
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/* Period parameters */
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#define N 624
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#define M 397
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#define MATRIX_A 0x9908b0dfUL /* constant vector a */
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#define UPPER_MASK 0x80000000UL /* most significant w-r bits */
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#define LOWER_MASK 0x7fffffffUL /* least significant r bits */
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static unsigned long mt[N]; /* the array for the state vector */
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static int mti = N+1; /* mti==N+1 means mt[N] is not initialized */
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/* initializes mt[N] with a seed */
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static void init_genrand (unsigned long s) {
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mt[0]= s & 0xffffffffUL;
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for (mti=1; mti<N; mti++) {
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mt[mti] =
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(1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti);
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/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
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/* In the previous versions, MSBs of the seed affect */
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/* only MSBs of the array mt[]. */
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/* 2002/01/09 modified by Makoto Matsumoto */
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mt[mti] &= 0xffffffffUL;
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/* for >32 bit machines */
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}
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}
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/* generates a random number on [0,0xffffffff]-interval */
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static unsigned long genrand_int32 (void) {
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unsigned long y;
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static unsigned long mag01[2]={0x0UL, MATRIX_A};
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/* mag01[x] = x * MATRIX_A for x=0,1 */
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if (mti >= N) { /* generate N words at one time */
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int kk;
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if (mti == N+1) /* if init_genrand() has not been called, */
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init_genrand(5489UL); /* a default initial seed is used */
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for (kk=0;kk<N-M;kk++) {
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y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
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mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1UL];
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}
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for (;kk<N-1;kk++) {
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y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
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mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
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}
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y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
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mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1UL];
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mti = 0;
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}
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y = mt[mti++];
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/* Tempering */
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y ^= (y >> 11);
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y ^= (y << 7) & 0x9d2c5680UL;
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y ^= (y << 15) & 0xefc60000UL;
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y ^= (y >> 18);
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return y;
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}
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////////////////////////////////////////////////////////////////////////////////
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/// @}
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////////////////////////////////////////////////////////////////////////////////
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// -----------------------------------------------------------------------------
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// --SECTION-- public functions
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// -----------------------------------------------------------------------------
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////////////////////////////////////////////////////////////////////////////////
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/// @addtogroup Random
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/// @{
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////////////////////////////////////////////////////////////////////////////////
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////////////////////////////////////////////////////////////////////////////////
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/// @brief initialise the mersenne twister
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/// this function needs to be called just once on startup
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////////////////////////////////////////////////////////////////////////////////
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void TRI_InitialiseMersenneTwister () {
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unsigned long seed = (unsigned long) time(0);
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#ifdef TRI_HAVE_GETTIMEOFDAY
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struct timeval tv;
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int result = gettimeofday(&tv, 0);
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seed ^= (unsigned long) tv.tv_sec;
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seed ^= (unsigned long) tv.tv_usec;
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seed ^= (unsigned long) result;
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#endif
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seed ^= (unsigned long) TRI_CurrentProcessId();
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init_genrand((unsigned long) seed);
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}
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////////////////////////////////////////////////////////////////////////////////
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/// @brief explicitly seed the mersenne twister
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////////////////////////////////////////////////////////////////////////////////
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void TRI_SeedMersenneTwister (uint32_t seed) {
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init_genrand((unsigned long) seed);
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}
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////////////////////////////////////////////////////////////////////////////////
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/// @brief generate a 31 bit random number
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////////////////////////////////////////////////////////////////////////////////
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uint32_t TRI_Int31MersenneTwister () {
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return (uint32_t) (genrand_int32() >> 1);
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}
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////////////////////////////////////////////////////////////////////////////////
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/// @brief generate a 32 bit random number
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////////////////////////////////////////////////////////////////////////////////
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uint32_t TRI_Int32MersenneTwister () {
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return (uint32_t) genrand_int32();
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}
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////////////////////////////////////////////////////////////////////////////////
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/// @}
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////////////////////////////////////////////////////////////////////////////////
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// Local Variables:
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// mode: outline-minor
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// outline-regexp: "/// @brief\\|/// {@inheritDoc}\\|/// @addtogroup\\|/// @page\\|// --SECTION--\\|/// @\\}"
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// End:
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