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142 lines
6.7 KiB
C
142 lines
6.7 KiB
C
/* Copyright (c) Mark Harmstone 2016-17
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*
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* This file is part of WinBtrfs.
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*
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* WinBtrfs is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public Licence as published by
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* the Free Software Foundation, either version 3 of the Licence, or
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* (at your option) any later version.
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*
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* WinBtrfs 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 Lesser General Public Licence for more details.
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*
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* You should have received a copy of the GNU Lesser General Public Licence
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* along with WinBtrfs. If not, see <http://www.gnu.org/licenses/>. */
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#include "btrfs_drv.h"
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static const UINT8 glog[] = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26,
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0x4c, 0x98, 0x2d, 0x5a, 0xb4, 0x75, 0xea, 0xc9, 0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30, 0x60, 0xc0,
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0x9d, 0x27, 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35, 0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23,
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0x46, 0x8c, 0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0, 0x5d, 0xba, 0x69, 0xd2, 0xb9, 0x6f, 0xde, 0xa1,
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0x5f, 0xbe, 0x61, 0xc2, 0x99, 0x2f, 0x5e, 0xbc, 0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0,
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0xfd, 0xe7, 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f, 0xfe, 0xe1, 0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2,
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0xd9, 0xaf, 0x43, 0x86, 0x11, 0x22, 0x44, 0x88, 0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd, 0x67, 0xce,
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0x81, 0x1f, 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93, 0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc,
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0x85, 0x17, 0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9, 0x4f, 0x9e, 0x21, 0x42, 0x84, 0x15, 0x2a, 0x54,
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0xa8, 0x4d, 0x9a, 0x29, 0x52, 0xa4, 0x55, 0xaa, 0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73,
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0xe6, 0xd1, 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e, 0xfc, 0xe5, 0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff,
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0xe3, 0xdb, 0xab, 0x4b, 0x96, 0x31, 0x62, 0xc4, 0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57, 0xae, 0x41,
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0x82, 0x19, 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e, 0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6,
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0x51, 0xa2, 0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef, 0xc3, 0x9b, 0x2b, 0x56, 0xac, 0x45, 0x8a, 0x09,
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0x12, 0x24, 0x48, 0x90, 0x3d, 0x7a, 0xf4, 0xf5, 0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16,
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0x2c, 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83, 0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x01};
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static const UINT8 gilog[] = {0x00, 0x00, 0x01, 0x19, 0x02, 0x32, 0x1a, 0xc6, 0x03, 0xdf, 0x33, 0xee, 0x1b, 0x68, 0xc7, 0x4b,
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0x04, 0x64, 0xe0, 0x0e, 0x34, 0x8d, 0xef, 0x81, 0x1c, 0xc1, 0x69, 0xf8, 0xc8, 0x08, 0x4c, 0x71,
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0x05, 0x8a, 0x65, 0x2f, 0xe1, 0x24, 0x0f, 0x21, 0x35, 0x93, 0x8e, 0xda, 0xf0, 0x12, 0x82, 0x45,
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0x1d, 0xb5, 0xc2, 0x7d, 0x6a, 0x27, 0xf9, 0xb9, 0xc9, 0x9a, 0x09, 0x78, 0x4d, 0xe4, 0x72, 0xa6,
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0x06, 0xbf, 0x8b, 0x62, 0x66, 0xdd, 0x30, 0xfd, 0xe2, 0x98, 0x25, 0xb3, 0x10, 0x91, 0x22, 0x88,
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0x36, 0xd0, 0x94, 0xce, 0x8f, 0x96, 0xdb, 0xbd, 0xf1, 0xd2, 0x13, 0x5c, 0x83, 0x38, 0x46, 0x40,
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0x1e, 0x42, 0xb6, 0xa3, 0xc3, 0x48, 0x7e, 0x6e, 0x6b, 0x3a, 0x28, 0x54, 0xfa, 0x85, 0xba, 0x3d,
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0xca, 0x5e, 0x9b, 0x9f, 0x0a, 0x15, 0x79, 0x2b, 0x4e, 0xd4, 0xe5, 0xac, 0x73, 0xf3, 0xa7, 0x57,
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0x07, 0x70, 0xc0, 0xf7, 0x8c, 0x80, 0x63, 0x0d, 0x67, 0x4a, 0xde, 0xed, 0x31, 0xc5, 0xfe, 0x18,
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0xe3, 0xa5, 0x99, 0x77, 0x26, 0xb8, 0xb4, 0x7c, 0x11, 0x44, 0x92, 0xd9, 0x23, 0x20, 0x89, 0x2e,
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0x37, 0x3f, 0xd1, 0x5b, 0x95, 0xbc, 0xcf, 0xcd, 0x90, 0x87, 0x97, 0xb2, 0xdc, 0xfc, 0xbe, 0x61,
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0xf2, 0x56, 0xd3, 0xab, 0x14, 0x2a, 0x5d, 0x9e, 0x84, 0x3c, 0x39, 0x53, 0x47, 0x6d, 0x41, 0xa2,
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0x1f, 0x2d, 0x43, 0xd8, 0xb7, 0x7b, 0xa4, 0x76, 0xc4, 0x17, 0x49, 0xec, 0x7f, 0x0c, 0x6f, 0xf6,
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0x6c, 0xa1, 0x3b, 0x52, 0x29, 0x9d, 0x55, 0xaa, 0xfb, 0x60, 0x86, 0xb1, 0xbb, 0xcc, 0x3e, 0x5a,
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0xcb, 0x59, 0x5f, 0xb0, 0x9c, 0xa9, 0xa0, 0x51, 0x0b, 0xf5, 0x16, 0xeb, 0x7a, 0x75, 0x2c, 0xd7,
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0x4f, 0xae, 0xd5, 0xe9, 0xe6, 0xe7, 0xad, 0xe8, 0x74, 0xd6, 0xf4, 0xea, 0xa8, 0x50, 0x58, 0xaf};
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// divides the bytes in data by 2^div
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void galois_divpower(UINT8* data, UINT8 div, UINT32 len) {
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while (len > 0) {
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if (data[0] != 0) {
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if (gilog[data[0]] <= div)
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data[0] = glog[(gilog[data[0]] + (255 - div)) % 255];
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else
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data[0] = glog[(gilog[data[0]] - div) % 255];
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}
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data++;
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len--;
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}
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}
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UINT8 gpow2(UINT8 e) {
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return glog[e%255];
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}
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UINT8 gmul(UINT8 a, UINT8 b) {
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if (a == 0 || b == 0)
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return 0;
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else
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return glog[(gilog[a] + gilog[b]) % 255];
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}
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UINT8 gdiv(UINT8 a, UINT8 b) {
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if (b == 0) {
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return 0xff; // shouldn't happen
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} else if (a == 0) {
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return 0;
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} else {
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if (gilog[a] >= gilog[b])
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return glog[(gilog[a] - gilog[b]) % 255];
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else
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return glog[255-((gilog[b] - gilog[a]) % 255)];
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}
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}
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// The code from the following functions is derived from the paper
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// "The mathematics of RAID-6", by H. Peter Anvin.
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// https://www.kernel.org/pub/linux/kernel/people/hpa/raid6.pdf
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#ifdef _AMD64_
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__inline static UINT64 galois_double_mask64(UINT64 v) {
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v &= 0x8080808080808080;
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return (v << 1) - (v >> 7);
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}
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#else
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__inline static UINT32 galois_double_mask32(UINT32 v) {
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v &= 0x80808080;
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return (v << 1) - (v >> 7);
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}
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#endif
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void galois_double(UINT8* data, UINT32 len) {
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// FIXME - SIMD?
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#ifdef _AMD64_
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while (len > sizeof(UINT64)) {
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UINT64 v = *((UINT64*)data), vv;
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vv = (v << 1) & 0xfefefefefefefefe;
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vv ^= galois_double_mask64(v) & 0x1d1d1d1d1d1d1d1d;
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*((UINT64*)data) = vv;
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data += sizeof(UINT64);
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len -= sizeof(UINT64);
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}
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#else
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while (len > sizeof(UINT32)) {
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UINT32 v = *((UINT32*)data), vv;
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vv = (v << 1) & 0xfefefefe;
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vv ^= galois_double_mask32(v) & 0x1d1d1d1d;
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*((UINT32*)data) = vv;
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data += sizeof(UINT32);
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len -= sizeof(UINT32);
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}
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#endif
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while (len > 0) {
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data[0] = (data[0] << 1) ^ ((data[0] & 0x80) ? 0x1d : 0);
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data++;
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len--;
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}
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}
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