ReactOS  0.4.14-dev-358-gbef841c
galois.c
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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_t 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_t 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
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 
70  return glog[e%255];
71 }
72 
74  if (a == 0 || b == 0)
75  return 0;
76  else
77  return glog[(gilog[a] + gilog[b]) % 255];
78 }
79 
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_t galois_double_mask64(uint64_t v) {
99  v &= 0x8080808080808080;
100  return (v << 1) - (v >> 7);
101 }
102 #else
104  v &= 0x80808080;
105  return (v << 1) - (v >> 7);
106 }
107 #endif
108 
110  // FIXME - SIMD?
111 
112 #ifdef _AMD64_
113  while (len > sizeof(uint64_t)) {
114  uint64_t v = *((uint64_t*)data), vv;
115 
116  vv = (v << 1) & 0xfefefefefefefefe;
117  vv ^= galois_double_mask64(v) & 0x1d1d1d1d1d1d1d1d;
118  *((uint64_t*)data) = vv;
119 
120  data += sizeof(uint64_t);
121  len -= sizeof(uint64_t);
122  }
123 #else
124  while (len > sizeof(uint32_t)) {
125  uint32_t v = *((uint32_t*)data), vv;
126 
127  vv = (v << 1) & 0xfefefefe;
128  vv ^= galois_double_mask32(v) & 0x1d1d1d1d;
129  *((uint32_t*)data) = vv;
130 
131  data += sizeof(uint32_t);
132  len -= sizeof(uint32_t);
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 }
static const uint8_t glog[]
Definition: galois.c:20
uint8_t gdiv(uint8_t a, uint8_t b)
Definition: galois.c:80
void galois_divpower(uint8_t *data, uint8_t div, uint32_t len)
Definition: galois.c:55
static const uint8_t gilog[]
Definition: galois.c:37
uint8_t gpow2(uint8_t e)
Definition: galois.c:69
#define a
Definition: ke_i.h:78
#define e
Definition: ke_i.h:82
#define b
Definition: ke_i.h:79
GLboolean GLboolean GLboolean b
Definition: glext.h:6204
_STLP_VENDOR_CSTD::ldiv_t div(long __x, long __y)
Definition: _cstdlib.h:137
GLint GLenum GLsizei GLsizei GLsizei GLint GLsizei const GLvoid * data
Definition: gl.h:1950
uint8_t gmul(uint8_t a, uint8_t b)
Definition: galois.c:73
GLenum GLsizei len
Definition: glext.h:6722
void galois_double(uint8_t *data, uint32_t len)
Definition: galois.c:109
BYTE uint8_t
Definition: msvideo1.c:66
#define uint64_t
Definition: nsiface.idl:62
UINT64 uint64_t
Definition: types.h:77
const GLdouble * v
Definition: gl.h:2040
UINT32 uint32_t
Definition: types.h:75
GLboolean GLboolean GLboolean GLboolean a
Definition: glext.h:6204
#define uint32_t
Definition: nsiface.idl:61
static __inline uint32_t galois_double_mask32(uint32_t v)
Definition: galois.c:103