1 /* Copyright (c) Mark Harmstone 2016-17 2 * 3 * This file is part of WinBtrfs. 4 * 5 * WinBtrfs is free software: you can redistribute it and/or modify 6 * it under the terms of the GNU Lesser General Public Licence as published by 7 * the Free Software Foundation, either version 3 of the Licence, or 8 * (at your option) any later version. 9 * 10 * WinBtrfs is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU Lesser General Public Licence for more details. 14 * 15 * You should have received a copy of the GNU Lesser General Public Licence 16 * along with WinBtrfs. If not, see <http://www.gnu.org/licenses/>. */ 17 18 #include "btrfs_drv.h" 19 20 static const UINT8 glog[] = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26, 21 0x4c, 0x98, 0x2d, 0x5a, 0xb4, 0x75, 0xea, 0xc9, 0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30, 0x60, 0xc0, 22 0x9d, 0x27, 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35, 0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23, 23 0x46, 0x8c, 0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0, 0x5d, 0xba, 0x69, 0xd2, 0xb9, 0x6f, 0xde, 0xa1, 24 0x5f, 0xbe, 0x61, 0xc2, 0x99, 0x2f, 0x5e, 0xbc, 0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0, 25 0xfd, 0xe7, 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f, 0xfe, 0xe1, 0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2, 26 0xd9, 0xaf, 0x43, 0x86, 0x11, 0x22, 0x44, 0x88, 0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd, 0x67, 0xce, 27 0x81, 0x1f, 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93, 0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc, 28 0x85, 0x17, 0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9, 0x4f, 0x9e, 0x21, 0x42, 0x84, 0x15, 0x2a, 0x54, 29 0xa8, 0x4d, 0x9a, 0x29, 0x52, 0xa4, 0x55, 0xaa, 0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73, 30 0xe6, 0xd1, 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e, 0xfc, 0xe5, 0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff, 31 0xe3, 0xdb, 0xab, 0x4b, 0x96, 0x31, 0x62, 0xc4, 0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57, 0xae, 0x41, 32 0x82, 0x19, 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e, 0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6, 33 0x51, 0xa2, 0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef, 0xc3, 0x9b, 0x2b, 0x56, 0xac, 0x45, 0x8a, 0x09, 34 0x12, 0x24, 0x48, 0x90, 0x3d, 0x7a, 0xf4, 0xf5, 0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16, 35 0x2c, 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83, 0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x01}; 36 37 static const UINT8 gilog[] = {0x00, 0x00, 0x01, 0x19, 0x02, 0x32, 0x1a, 0xc6, 0x03, 0xdf, 0x33, 0xee, 0x1b, 0x68, 0xc7, 0x4b, 38 0x04, 0x64, 0xe0, 0x0e, 0x34, 0x8d, 0xef, 0x81, 0x1c, 0xc1, 0x69, 0xf8, 0xc8, 0x08, 0x4c, 0x71, 39 0x05, 0x8a, 0x65, 0x2f, 0xe1, 0x24, 0x0f, 0x21, 0x35, 0x93, 0x8e, 0xda, 0xf0, 0x12, 0x82, 0x45, 40 0x1d, 0xb5, 0xc2, 0x7d, 0x6a, 0x27, 0xf9, 0xb9, 0xc9, 0x9a, 0x09, 0x78, 0x4d, 0xe4, 0x72, 0xa6, 41 0x06, 0xbf, 0x8b, 0x62, 0x66, 0xdd, 0x30, 0xfd, 0xe2, 0x98, 0x25, 0xb3, 0x10, 0x91, 0x22, 0x88, 42 0x36, 0xd0, 0x94, 0xce, 0x8f, 0x96, 0xdb, 0xbd, 0xf1, 0xd2, 0x13, 0x5c, 0x83, 0x38, 0x46, 0x40, 43 0x1e, 0x42, 0xb6, 0xa3, 0xc3, 0x48, 0x7e, 0x6e, 0x6b, 0x3a, 0x28, 0x54, 0xfa, 0x85, 0xba, 0x3d, 44 0xca, 0x5e, 0x9b, 0x9f, 0x0a, 0x15, 0x79, 0x2b, 0x4e, 0xd4, 0xe5, 0xac, 0x73, 0xf3, 0xa7, 0x57, 45 0x07, 0x70, 0xc0, 0xf7, 0x8c, 0x80, 0x63, 0x0d, 0x67, 0x4a, 0xde, 0xed, 0x31, 0xc5, 0xfe, 0x18, 46 0xe3, 0xa5, 0x99, 0x77, 0x26, 0xb8, 0xb4, 0x7c, 0x11, 0x44, 0x92, 0xd9, 0x23, 0x20, 0x89, 0x2e, 47 0x37, 0x3f, 0xd1, 0x5b, 0x95, 0xbc, 0xcf, 0xcd, 0x90, 0x87, 0x97, 0xb2, 0xdc, 0xfc, 0xbe, 0x61, 48 0xf2, 0x56, 0xd3, 0xab, 0x14, 0x2a, 0x5d, 0x9e, 0x84, 0x3c, 0x39, 0x53, 0x47, 0x6d, 0x41, 0xa2, 49 0x1f, 0x2d, 0x43, 0xd8, 0xb7, 0x7b, 0xa4, 0x76, 0xc4, 0x17, 0x49, 0xec, 0x7f, 0x0c, 0x6f, 0xf6, 50 0x6c, 0xa1, 0x3b, 0x52, 0x29, 0x9d, 0x55, 0xaa, 0xfb, 0x60, 0x86, 0xb1, 0xbb, 0xcc, 0x3e, 0x5a, 51 0xcb, 0x59, 0x5f, 0xb0, 0x9c, 0xa9, 0xa0, 0x51, 0x0b, 0xf5, 0x16, 0xeb, 0x7a, 0x75, 0x2c, 0xd7, 52 0x4f, 0xae, 0xd5, 0xe9, 0xe6, 0xe7, 0xad, 0xe8, 0x74, 0xd6, 0xf4, 0xea, 0xa8, 0x50, 0x58, 0xaf}; 53 54 // divides the bytes in data by 2^div 55 void galois_divpower(UINT8* data, UINT8 div, UINT32 len) { 56 while (len > 0) { 57 if (data[0] != 0) { 58 if (gilog[data[0]] <= div) 59 data[0] = glog[(gilog[data[0]] + (255 - div)) % 255]; 60 else 61 data[0] = glog[(gilog[data[0]] - div) % 255]; 62 } 63 64 data++; 65 len--; 66 } 67 } 68 69 UINT8 gpow2(UINT8 e) { 70 return glog[e%255]; 71 } 72 73 UINT8 gmul(UINT8 a, UINT8 b) { 74 if (a == 0 || b == 0) 75 return 0; 76 else 77 return glog[(gilog[a] + gilog[b]) % 255]; 78 } 79 80 UINT8 gdiv(UINT8 a, UINT8 b) { 81 if (b == 0) { 82 return 0xff; // shouldn't happen 83 } else if (a == 0) { 84 return 0; 85 } else { 86 if (gilog[a] >= gilog[b]) 87 return glog[(gilog[a] - gilog[b]) % 255]; 88 else 89 return glog[255-((gilog[b] - gilog[a]) % 255)]; 90 } 91 } 92 93 // The code from the following functions is derived from the paper 94 // "The mathematics of RAID-6", by H. Peter Anvin. 95 // https://www.kernel.org/pub/linux/kernel/people/hpa/raid6.pdf 96 97 #ifdef _AMD64_ 98 __inline static UINT64 galois_double_mask64(UINT64 v) { 99 v &= 0x8080808080808080; 100 return (v << 1) - (v >> 7); 101 } 102 #else 103 __inline static UINT32 galois_double_mask32(UINT32 v) { 104 v &= 0x80808080; 105 return (v << 1) - (v >> 7); 106 } 107 #endif 108 109 void galois_double(UINT8* data, UINT32 len) { 110 // FIXME - SIMD? 111 112 #ifdef _AMD64_ 113 while (len > sizeof(UINT64)) { 114 UINT64 v = *((UINT64*)data), vv; 115 116 vv = (v << 1) & 0xfefefefefefefefe; 117 vv ^= galois_double_mask64(v) & 0x1d1d1d1d1d1d1d1d; 118 *((UINT64*)data) = vv; 119 120 data += sizeof(UINT64); 121 len -= sizeof(UINT64); 122 } 123 #else 124 while (len > sizeof(UINT32)) { 125 UINT32 v = *((UINT32*)data), vv; 126 127 vv = (v << 1) & 0xfefefefe; 128 vv ^= galois_double_mask32(v) & 0x1d1d1d1d; 129 *((UINT32*)data) = vv; 130 131 data += sizeof(UINT32); 132 len -= sizeof(UINT32); 133 } 134 #endif 135 136 while (len > 0) { 137 data[0] = (data[0] << 1) ^ ((data[0] & 0x80) ? 0x1d : 0); 138 data++; 139 len--; 140 } 141 } 142