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1 //-----------------------------------------------------------------------------
2 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
3 // at your option, any later version. See the LICENSE.txt file for the text of
4 // the license.
5 //-----------------------------------------------------------------------------
6 // Parity functions
7 //-----------------------------------------------------------------------------
8
9 // all functions defined in header file by purpose. Allows compiler optimizations.
10
11 #ifndef __PARITY_H
12 #define __PARITY_H
13
14 #include <stdint.h>
15 #include <stdbool.h>
16 #include "string.h"
17
18 extern const uint8_t OddByteParity[256];
19
20
21 static inline bool oddparity8(const uint8_t x) {
22 return OddByteParity[x];
23 }
24
25 static inline void oddparitybuf(const uint8_t *x, size_t len, uint8_t *parity) {
26 memset(parity, 0x00, (len - 1) / 8 + 1);
27 for (int i = 0; i < len; i++)
28 parity[i / 8] |= oddparity8(x[i]) << (7 - (i % 8));
29 }
30
31 static inline bool evenparity8(const uint8_t x) {
32 return !OddByteParity[x];
33 }
34
35
36 static inline bool evenparity32(uint32_t x)
37 {
38 #if !defined __GNUC__
39 x ^= x >> 16;
40 x ^= x >> 8;
41 return evenparity8(x);
42 #else
43 return __builtin_parity(x);
44 #endif
45 }
46
47
48 static inline bool oddparity32(uint32_t x)
49 {
50 #if !defined __GNUC__
51 x ^= x >> 16;
52 x ^= x >> 8;
53 return oddparity8(x);
54 #else
55 return !__builtin_parity(x);
56 #endif
57 }
58
59 #endif /* __PARITY_H */
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