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96 lines
1.7 KiB
C
96 lines
1.7 KiB
C
/*
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* Original copy from:
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* linux/fs/ext3/hash.c
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*
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* Copyright (C) 2002 by Theodore Ts'o
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*
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* This file is released under the GPL v2.
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*
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* This file may be redistributed under the terms of the GNU Public
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* License.
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*/
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#include <linux/types.h>
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#include "hash.h"
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#define DELTA 0x9E3779B9
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static void TEA_transform(__u32 buf[2], __u32 const in[])
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{
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__u32 sum = 0;
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__u32 b0 = buf[0], b1 = buf[1];
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__u32 a = in[0], b = in[1], c = in[2], d = in[3];
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int n = 16;
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do {
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sum += DELTA;
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b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
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b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
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} while(--n);
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buf[0] += b0;
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buf[1] += b1;
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}
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static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)
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{
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__u32 pad, val;
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int i;
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pad = (__u32)len | ((__u32)len << 8);
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pad |= pad << 16;
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val = pad;
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if (len > num*4)
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len = num * 4;
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for (i=0; i < len; i++) {
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if ((i % 4) == 0)
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val = pad;
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val = msg[i] + (val << 8);
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if ((i % 4) == 3) {
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*buf++ = val;
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val = pad;
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num--;
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}
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}
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if (--num >= 0)
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*buf++ = val;
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while (--num >= 0)
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*buf++ = pad;
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}
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int btrfs_name_hash(const char *name, int len, u64 *hash_result)
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{
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__u32 hash;
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__u32 minor_hash = 0;
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const char *p;
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__u32 in[8], buf[2];
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if (len == 1 && *name == '.') {
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*hash_result = 1;
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return 0;
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} else if (len == 2 && name[0] == '.' && name[1] == '.') {
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*hash_result = 2;
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return 0;
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}
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/* Initialize the default seed for the hash checksum functions */
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buf[0] = 0x67452301;
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buf[1] = 0xefcdab89;
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buf[2] = 0x98badcfe;
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buf[3] = 0x10325476;
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p = name;
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while (len > 0) {
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str2hashbuf(p, len, in, 4);
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TEA_transform(buf, in);
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len -= 16;
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p += 16;
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}
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hash = buf[0];
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minor_hash = buf[1];
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*hash_result = buf[0];
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*hash_result <<= 32;
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*hash_result |= buf[1];
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return 0;
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}
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