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209 lines
7.4 KiB
C#
209 lines
7.4 KiB
C#
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/**
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* @brief SIMD oriented Fast Mersenne Twister(SFMT)
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*
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* @author Mutsuo Saito (Hiroshima University)
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* @author Makoto Matsumoto (Hiroshima University)
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*
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* C# port by morkt
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*
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* Copyright (C) 2006, 2007 Mutsuo Saito, Makoto Matsumoto and Hiroshima University.
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* Copyright (C) 2012 Mutsuo Saito, Makoto Matsumoto, Hiroshima University and The University of Tokyo.
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* Copyright (C) 2013 Mutsuo Saito, Makoto Matsumoto and Hiroshima University.
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* All rights reserved.
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*
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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 are met:
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*
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* * 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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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials provided
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* with the distribution.
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* * Neither the names of Hiroshima University, The University of
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* Tokyo nor the names of its contributors may be used to endorse
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* or promote products derived from this software without specific
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* prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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namespace GameRes.Utility
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{
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public class FastMersenneTwister
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{
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const int MEXP = 19937;
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const int N = MEXP / 128 + 1;
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const int N32 = N * 4;
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const int POS1 = 122;
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const int SL1 = 18;
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const int SL2 = 1;
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const int SR1 = 11;
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const int SR2 = 1;
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const uint MSK1 = 0xdfffffefU;
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const uint MSK2 = 0xddfecb7fU;
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const uint MSK3 = 0xbffaffffU;
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const uint MSK4 = 0xbffffff6U;
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const uint PARITY1 = 0x00000001U;
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const uint PARITY2 = 0x00000000U;
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const uint PARITY3 = 0x00000000U;
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const uint PARITY4 = 0x13c9e684U;
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uint[,] m_state = new uint[N,4];
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int m_idx;
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public FastMersenneTwister (uint seed)
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{
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SRand (seed);
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}
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public void SRand (uint seed)
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{
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uint prev = m_state[0,0] = seed;
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for (int i = 1; i < N32; i++)
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{
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int p = i >> 2;
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int k = i & 3;
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prev = (uint)(1812433253UL * (prev ^ (prev >> 30)) + (uint)i);
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m_state[p,k] = prev;
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}
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m_idx = N32;
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period_certification();
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}
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public uint GetRand32 ()
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{
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if (m_idx >= N32)
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{
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sfmt_gen_rand_all();
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m_idx = 0;
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}
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uint r = m_state[m_idx >> 2, m_idx & 3];
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m_idx++;
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return r;
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}
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/// <summary>
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/// This function fills the internal state array with pseudorandom integers.
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/// </summary>
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void sfmt_gen_rand_all ()
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{
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int i;
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int r1 = N - 2;
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int r2 = N - 1;
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for (i = 0; i < N - POS1; i++)
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{
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do_recursion (i, i, i + POS1, r1, r2);
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r1 = r2;
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r2 = i;
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}
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for (; i < N; i++)
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{
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do_recursion (i, i, i + POS1 - N, r1, r2);
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r1 = r2;
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r2 = i;
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}
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}
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/// <summary>
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/// This function represents the recursion formula.
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/// </summary>
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void do_recursion (int r, int a, int b, int c, int d)
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{
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var x = new uint[4];
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var y = new uint[4];
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lshift128 (x, a, SL2);
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rshift128 (y, c, SR2);
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m_state[r,0] = m_state[a,0] ^ x[0] ^ ((m_state[b,0] >> SR1) & MSK1)
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^ y[0] ^ (m_state[d,0] << SL1);
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m_state[r,1] = m_state[a,1] ^ x[1] ^ ((m_state[b,1] >> SR1) & MSK2)
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^ y[1] ^ (m_state[d,1] << SL1);
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m_state[r,2] = m_state[a,2] ^ x[2] ^ ((m_state[b,2] >> SR1) & MSK3)
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^ y[2] ^ (m_state[d,2] << SL1);
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m_state[r,3] = m_state[a,3] ^ x[3] ^ ((m_state[b,3] >> SR1) & MSK4)
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^ y[3] ^ (m_state[d,3] << SL1);
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}
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static readonly uint[] s_parity = { PARITY1, PARITY2, PARITY3, PARITY4 };
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/// <summary>
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/// This function certificate the period of 2^{MEXP}
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/// </summary>
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void period_certification ()
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{
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uint inner = 0;
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int i;
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for (i = 0; i < 4; i++)
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inner ^= m_state[0,i] & s_parity[i];
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for (i = 16; i > 0; i >>= 1)
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inner ^= inner >> i;
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inner &= 1;
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/* check OK */
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if (inner == 1)
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return;
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/* check NG, and modification */
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for (i = 0; i < 4; i++)
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{
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uint work = 1;
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for (int j = 0; j < 32; j++)
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{
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if ((work & s_parity[i]) != 0)
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{
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m_state[0,i] ^= work;
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return;
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}
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work = work << 1;
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}
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}
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}
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/// <summary>
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/// This function simulates SIMD 128-bit left shift.
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/// The 128-bit integer referenced by idx is shifted by (shift * 8) bits.
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/// This function simulates the LITTLE ENDIAN SIMD.
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/// </summary>
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/// <param name="result">the output of this function</param>
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/// <param name="idx">index within state array of the 128-bit data to be shifted</param>
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/// <param name="shift">the shift value</param>
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void lshift128 (uint[] result, int idx, int shift)
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{
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ulong th = ((ulong)m_state[idx,3] << 32) | ((ulong)m_state[idx,2]);
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ulong tl = ((ulong)m_state[idx,1] << 32) | ((ulong)m_state[idx,0]);
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ulong oh = th << (shift * 8);
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ulong ol = tl << (shift * 8);
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oh |= tl >> (64 - shift * 8);
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result[1] = (uint)(ol >> 32);
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result[0] = (uint)ol;
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result[3] = (uint)(oh >> 32);
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result[2] = (uint)oh;
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}
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void rshift128 (uint[] result, int idx, int shift)
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{
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ulong th = ((ulong)m_state[idx,3] << 32) | ((ulong)m_state[idx,2]);
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ulong tl = ((ulong)m_state[idx,1] << 32) | ((ulong)m_state[idx,0]);
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ulong oh = th >> (shift * 8);
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ulong ol = tl >> (shift * 8);
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ol |= th << (64 - shift * 8);
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result[1] = (uint)(ol >> 32);
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result[0] = (uint)ol;
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result[3] = (uint)(oh >> 32);
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result[2] = (uint)oh;
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}
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}
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}
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