Release 4.11 net/ceph/ceph_hash.c

#include <linux/ceph/types.h>
#include <linux/module.h>

/*
 * Robert Jenkin's hash function.
 * http://burtleburtle.net/bob/hash/evahash.html
 * This is in the public domain.
 */

#define mix(a, b, c)						\
	do {                                                    \
                a = a - b;  a = a - c;  a = a ^ (c >> 13);      \
                b = b - c;  b = b - a;  b = b ^ (a << 8);       \
                c = c - a;  c = c - b;  c = c ^ (b >> 13);      \
                a = a - b;  a = a - c;  a = a ^ (c >> 12);      \
                b = b - c;  b = b - a;  b = b ^ (a << 16);      \
                c = c - a;  c = c - b;  c = c ^ (b >> 5);       \
                a = a - b;  a = a - c;  a = a ^ (c >> 3);       \
                b = b - c;  b = b - a;  b = b ^ (a << 10);      \
                c = c - a;  c = c - b;  c = c ^ (b >> 15);      \
        } while (0)



unsigned int ceph_str_hash_rjenkins(const char *str, unsigned int length)
{
	const unsigned char *k = (const unsigned char *)str;
	__u32 a, b, c;  /* the internal state */
	__u32 len;      /* how many key bytes still need mixing */

	/* Set up the internal state */
	len = length;
	a = 0x9e3779b9;      /* the golden ratio; an arbitrary value */
	b = a;
	c = 0;               /* variable initialization of internal state */

	/* handle most of the key */
	while (len >= 12) {
		a = a + (k[0] + ((__u32)k[1] << 8) + ((__u32)k[2] << 16) +
			 ((__u32)k[3] << 24));
		b = b + (k[4] + ((__u32)k[5] << 8) + ((__u32)k[6] << 16) +
			 ((__u32)k[7] << 24));
		c = c + (k[8] + ((__u32)k[9] << 8) + ((__u32)k[10] << 16) +
			 ((__u32)k[11] << 24));
		mix(a, b, c);
		k = k + 12;
		len = len - 12;
	}

	/* handle the last 11 bytes */
	c = c + length;
	switch (len) {            /* all the case statements fall through */
	case 11:
		c = c + ((__u32)k[10] << 24);
	case 10:
		c = c + ((__u32)k[9] << 16);
	case 9:
		c = c + ((__u32)k[8] << 8);
		/* the first byte of c is reserved for the length */
	case 8:
		b = b + ((__u32)k[7] << 24);
	case 7:
		b = b + ((__u32)k[6] << 16);
	case 6:
		b = b + ((__u32)k[5] << 8);
	case 5:
		b = b + k[4];
	case 4:
		a = a + ((__u32)k[3] << 24);
	case 3:
		a = a + ((__u32)k[2] << 16);
	case 2:
		a = a + ((__u32)k[1] << 8);
	case 1:
		a = a + k[0];
		/* case 0: nothing left to add */
	}
	mix(a, b, c);

	return c;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Sage Weil
452
99.56%
1
50.00%
Eric Dumazet
2
0.44%
1
50.00%
Total
454
100.00%
2
100.00%

/*
 * linux dcache hash
 */


unsigned int ceph_str_hash_linux(const char *str, unsigned int length)
{
	unsigned long hash = 0;
	unsigned char c;

	while (length--) {
		c = *str++;
		hash = (hash + (c << 4) + (c >> 4)) * 11;
	}
	return hash;
}


Contributors
Person
Tokens
Prop
Commits
CommitProp
Sage Weil
59
96.72%
1
50.00%
Eric Dumazet
2
3.28%
1
50.00%
Total
61
100.00%
2
100.00%



unsigned int ceph_str_hash(int type, const char *s, unsigned int len)
{
	switch (type) {
	case CEPH_STR_HASH_LINUX:
		return ceph_str_hash_linux(s, len);
	case CEPH_STR_HASH_RJENKINS:
		return ceph_str_hash_rjenkins(s, len);
	default:
		return -1;
	}
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Sage Weil
49
96.08%
1
50.00%
Eric Dumazet
2
3.92%
1
50.00%
Total
51
100.00%
2
100.00%


EXPORT_SYMBOL(ceph_str_hash);



const char *ceph_str_hash_name(int type)
{
	switch (type) {
	case CEPH_STR_HASH_LINUX:
		return "linux";
	case CEPH_STR_HASH_RJENKINS:
		return "rjenkins";
	default:
		return "unknown";
	}
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Sage Weil
32
100.00%
1
100.00%
Total
32
100.00%
1
100.00%


EXPORT_SYMBOL(ceph_str_hash_name);
Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
Sage Weil
621
98.89%
2
50.00%
Eric Dumazet
6
0.96%
1
25.00%
Yehuda Sadeh Weinraub
1
0.16%
1
25.00%
Total
628
100.00%
4
100.00%
Directory: net/ceph

Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.