128 lines
3.6 KiB
C
128 lines
3.6 KiB
C
#ifndef M4RI_PARITY_H
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#define M4RI_PARITY_H
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/*******************************************************************
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*
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* M4RI: Linear Algebra over GF(2)
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*
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* Copyright (C) 2008 David Harvey <dmharvey@cims.nyu.edu>
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*
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* Distributed under the terms of the GNU General Public License (GPL)
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* version 2 or higher.
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*
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* This code 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 GNU
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* General Public License for more details.
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*
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* The full text of the GPL is available at:
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*
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* http://www.gnu.org/licenses/
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*
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********************************************************************/
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/**
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* \file parity.h
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*
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* \brief Compute the parity of 64 words in parallel.
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*
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* \author David Harvey
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*/
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#include <m4ri/misc.h>
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/**
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* \brief Step for mixing two 64-bit words to compute their parity.
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*/
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#define __M4RI_MIX32(a, b) (((((a) >> 32) ^ (a)) << 32) | \
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((((b) << 32) ^ (b)) >> 32))
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/**
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* \brief Step for mixing two 64-bit words to compute their parity.
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*/
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#define __M4RI_MIX16(a, b) (((((a) << 16) ^ (a)) & __M4RI_CONVERT_TO_WORD(0xFFFF0000FFFF0000ull)) | \
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((((b) >> 16) ^ (b)) & __M4RI_CONVERT_TO_WORD(0x0000FFFF0000FFFFull)));
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/**
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* \brief Step for mixing two 64-bit words to compute their parity.
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*/
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#define __M4RI_MIX8(a, b) (((((a) << 8) ^ (a)) & __M4RI_CONVERT_TO_WORD(0xFF00FF00FF00FF00ull)) | \
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((((b) >> 8) ^ (b)) & __M4RI_CONVERT_TO_WORD(0x00FF00FF00FF00FFull)));
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/**
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* \brief Step for mixing two 64-bit words to compute their parity.
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*/
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#define __M4RI_MIX4(a, b) (((((a) << 4) ^ (a)) & __M4RI_CONVERT_TO_WORD(0xF0F0F0F0F0F0F0F0ull)) | \
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((((b) >> 4) ^ (b)) & __M4RI_CONVERT_TO_WORD(0x0F0F0F0F0F0F0F0Full)));
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/**
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* \brief Step for mixing two 64-bit words to compute their parity.
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*/
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#define __M4RI_MIX2(a, b) (((((a) << 2) ^ (a)) & __M4RI_CONVERT_TO_WORD(0xCCCCCCCCCCCCCCCCull)) | \
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((((b) >> 2) ^ (b)) & __M4RI_CONVERT_TO_WORD(0x3333333333333333ull)));
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/**
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* \brief Step for mixing two 64-bit words to compute their parity.
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*/
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#define __M4RI_MIX1(a, b) (((((a) << 1) ^ (a)) & __M4RI_CONVERT_TO_WORD(0xAAAAAAAAAAAAAAAAull)) | \
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((((b) >> 1) ^ (b)) & __M4RI_CONVERT_TO_WORD(0x5555555555555555ull)));
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/**
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* \brief See parity64.
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*/
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static inline word m4ri_parity64_helper(word *buf)
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{
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word a0, a1, b0, b1, c0, c1;
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a0 = __M4RI_MIX32(buf[0x20], buf[0x00]);
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a1 = __M4RI_MIX32(buf[0x30], buf[0x10]);
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b0 = __M4RI_MIX16(a1, a0);
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a0 = __M4RI_MIX32(buf[0x28], buf[0x08]);
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a1 = __M4RI_MIX32(buf[0x38], buf[0x18]);
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b1 = __M4RI_MIX16(a1, a0);
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c0 = __M4RI_MIX8(b1, b0);
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a0 = __M4RI_MIX32(buf[0x24], buf[0x04]);
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a1 = __M4RI_MIX32(buf[0x34], buf[0x14]);
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b0 = __M4RI_MIX16(a1, a0);
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a0 = __M4RI_MIX32(buf[0x2C], buf[0x0C]);
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a1 = __M4RI_MIX32(buf[0x3C], buf[0x1C]);
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b1 = __M4RI_MIX16(a1, a0);
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c1 = __M4RI_MIX8(b1, b0);
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return __M4RI_MIX4(c1, c0);
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}
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/**
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* \brief Computes parity of each of buf[0], buf[1], ..., buf[63].
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* Returns single word whose bits are the parities of buf[0], ...,
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* buf[63].
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*
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* \param buf buffer of words of length 64
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*/
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static inline word m4ri_parity64(word *buf)
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{
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word d0, d1, e0, e1;
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d0 = m4ri_parity64_helper(buf);
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d1 = m4ri_parity64_helper(buf + 2);
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e0 = __M4RI_MIX2(d1, d0);
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d0 = m4ri_parity64_helper(buf + 1);
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d1 = m4ri_parity64_helper(buf + 3);
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e1 = __M4RI_MIX2(d1, d0);
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return __M4RI_MIX1(e1, e0);
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}
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#endif // M4RI_PARITY_H
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