138 lines
2.6 KiB
C
138 lines
2.6 KiB
C
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/*
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* Copyright (C) 2013 Andrea Mazzoleni
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*
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* This program 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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*
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* This program 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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*/
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#ifndef __RAID_GF_H
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#define __RAID_GF_H
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/*
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* Galois field operations.
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*
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* Basic range checks are implemented using BUG_ON().
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*/
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/*
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* GF a*b.
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*/
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static __always_inline uint8_t mul(uint8_t a, uint8_t b)
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{
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return gfmul[a][b];
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}
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/*
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* GF 1/a.
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* Not defined for a == 0.
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*/
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static __always_inline uint8_t inv(uint8_t v)
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{
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BUG_ON(v == 0); /* division by zero */
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return gfinv[v];
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}
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/*
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* GF 2^a.
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*/
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static __always_inline uint8_t pow2(int v)
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{
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BUG_ON(v < 0 || v > 254); /* invalid exponent */
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return gfexp[v];
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}
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/*
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* Gets the multiplication table for a specified value.
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*/
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static __always_inline const uint8_t *table(uint8_t v)
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{
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return gfmul[v];
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}
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/*
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* Gets the generator matrix coefficient for parity 'p' and disk 'd'.
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*/
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static __always_inline uint8_t A(int p, int d)
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{
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return gfgen[p][d];
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}
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/*
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* Dereference as uint8_t
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*/
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#define v_8(p) (*(uint8_t *)&(p))
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/*
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* Dereference as uint32_t
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*/
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#define v_32(p) (*(uint32_t *)&(p))
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/*
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* Dereference as uint64_t
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*/
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#define v_64(p) (*(uint64_t *)&(p))
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/*
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* Multiply each byte of a uint32 by 2 in the GF(2^8).
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*/
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static __always_inline uint32_t x2_32(uint32_t v)
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{
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uint32_t mask = v & 0x80808080U;
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mask = (mask << 1) - (mask >> 7);
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v = (v << 1) & 0xfefefefeU;
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v ^= mask & 0x1d1d1d1dU;
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return v;
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}
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/*
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* Multiply each byte of a uint64 by 2 in the GF(2^8).
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*/
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static __always_inline uint64_t x2_64(uint64_t v)
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{
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uint64_t mask = v & 0x8080808080808080ULL;
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mask = (mask << 1) - (mask >> 7);
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v = (v << 1) & 0xfefefefefefefefeULL;
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v ^= mask & 0x1d1d1d1d1d1d1d1dULL;
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return v;
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}
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/*
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* Divide each byte of a uint32 by 2 in the GF(2^8).
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*/
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static __always_inline uint32_t d2_32(uint32_t v)
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{
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uint32_t mask = v & 0x01010101U;
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mask = (mask << 8) - mask;
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v = (v >> 1) & 0x7f7f7f7fU;
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v ^= mask & 0x8e8e8e8eU;
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return v;
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}
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/*
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* Divide each byte of a uint64 by 2 in the GF(2^8).
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*/
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static __always_inline uint64_t d2_64(uint64_t v)
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{
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uint64_t mask = v & 0x0101010101010101ULL;
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mask = (mask << 8) - mask;
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v = (v >> 1) & 0x7f7f7f7f7f7f7f7fULL;
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v ^= mask & 0x8e8e8e8e8e8e8e8eULL;
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return v;
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}
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#endif
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