1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
|
/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */
#include "lib.h"
#include "primes.h"
static const unsigned int primes[] = {
#define PRIME_SKIP_COUNT 3
17,
37,
67,
131,
257, /* next from 2^8 */
521,
1031,
2053,
4099,
8209,
16411,
32771,
65537, /* next from 2^16 */
131101,
262147,
524309,
1048583,
2097169,
4194319,
8388617,
16777259, /* next from 2^24 */
33554467,
67108879,
134217757,
268435459,
536870923,
1073741827,
2147483659U,
4294967291U /* previous from 2^32 */
};
unsigned int primes_closest(unsigned int num)
{
unsigned int i;
for (i = 31; i > PRIME_SKIP_COUNT; i--) {
if ((num & (1U << i)) != 0)
return primes[i - PRIME_SKIP_COUNT];
}
return primes[0];
}
|
