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/*
* csum.c
*
* Copyright (C) 2014 SUSE. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
/*
* This implementation is based on the work from https://github.com/PeterScott/murmur3
*/
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <assert.h>
#include <string.h>
#include "csum.h"
#include "util.h"
#include "debug.h"
#define HASH_TYPE_MURMUR3 "Murmur3 "
#ifdef __GNUC__
#define FORCE_INLINE __attribute__((always_inline)) inline
#else
#define FORCE_INLINE inline
#endif
static FORCE_INLINE uint32_t rotl32(uint32_t x,int8_t r)
{
return (x << r) | (x >> (32 - r));
}
static FORCE_INLINE uint64_t rotl64(uint64_t x,int8_t r)
{
return (x << r) | (x >> (64 - r));
}
#define ROTL32(x,y) rotl32(x,y)
#define ROTL64(x,y) rotl64(x,y)
#define BIG_CONSTANT(x) (x##LLU)
#define getblock(p, i) (p[i])
static FORCE_INLINE uint32_t fmix32(uint32_t h)
{
h ^= h >> 16;
h *= 0x85ebca6b;
h ^= h >> 13;
h *= 0xc2b2ae35;
h ^= h >> 16;
return h;
}
static FORCE_INLINE uint64_t fmix64(uint64_t k)
{
k ^= k >> 33;
k *= BIG_CONSTANT(0xff51afd7ed558ccd);
k ^= k >> 33;
k *= BIG_CONSTANT(0xc4ceb9fe1a85ec53);
k ^= k >> 33;
return k;
}
static int murmur3_init_hash(unsigned int *ret_digest_len)
{
*ret_digest_len = 16;
return 0;
}
#define REM_BUFFER_LEN 15
struct murmur3_running_checksum {
uint64_t h1;
uint64_t h2;
uint64_t len;
unsigned char rem_buffer[REM_BUFFER_LEN]; /* Holds partial block between calls */
unsigned int rem_len;
};
DECLARE_RUNNING_CSUM_CAST_FUNCS(murmur3_running_checksum);
static struct running_checksum *murmur3_start_running_checksum(void)
{
struct murmur3_running_checksum *c =
calloc(1, sizeof(struct murmur3_running_checksum));
if (c) {
/* Init h1 & h2 with the same seed */
c->h1 = 42;
c->h2 = 42;
c->len = 0;
c->rem_len = 0;
}
return priv_to_rc(c);
}
static void murmur3_add_to_running_checksum(struct running_checksum *_c,
unsigned int len,
unsigned char *buf)
{
struct murmur3_running_checksum *c = rc_to_priv(_c);
unsigned char block[16];
const uint8_t * data = (const uint8_t*)buf;
int i;
uint64_t c1 = BIG_CONSTANT(0x87c37b91114253d5);
uint64_t c2 = BIG_CONSTANT(0x4cf5ad432745937f);
abort_on(c->rem_len > REM_BUFFER_LEN);
/* Process pending data first */
if(c->rem_len + len >= 16 && c->rem_len != 0){
memcpy(block, c->rem_buffer, c->rem_len);
for(i = 0; i < (16 - c->rem_len); i++)
block[c->rem_len + i] = data[i];
data = data + (16 - c->rem_len);
len -= (16 - c->rem_len);
c->rem_len = 0;
add_to_running_checksum(_c, 16, block);
}
/* We will now process 16-bytes blocks, as much as possible */
while(len >= 16){
uint64_t k1, k2;
memcpy(&k1, data, sizeof(k1));
memcpy(&k2, data + sizeof(k1), sizeof(k2));
k1 *= c1;
k1 = ROTL64(k1, 31);
k1 *= c2;
c->h1 ^= k1;
c->h1 = ROTL64(c->h1, 27);
c->h1 += c->h2;
c->h1 = c->h1 * 5 + 0x52dce729;
k2 *= c2;
k2 = ROTL64(k2, 33);
k2 *= c1;
c->h2 ^= k2;
c->h2 = ROTL64(c->h2, 31);
c->h2 += c->h1;
c->h2 = c->h2 * 5 + 0x38495ab5;
/* Move the cursor to process the next block */
data += 16;
c->len += 16;
len -= 16;
}
/* We will concat instead of just copy
* we can update multiple too-low blocks in a row
*/
abort_on((c->rem_len + len) > REM_BUFFER_LEN);
memcpy(&c->rem_buffer[c->rem_len], data, len);
c->rem_len += len;
}
static void checksum_tailing_data(struct murmur3_running_checksum *c)
{
uint64_t c1 = BIG_CONSTANT(0x87c37b91114253d5);
uint64_t c2 = BIG_CONSTANT(0x4cf5ad432745937f);
const uint8_t * tail = c->rem_buffer;
c->len += c->rem_len;
uint64_t k1 = 0;
uint64_t k2 = 0;
switch(c->len & 15){
case 15:
k2 ^= (uint64_t)(tail[14]) << 48;
case 14:
k2 ^= (uint64_t)(tail[13]) << 40;
case 13:
k2 ^= (uint64_t)(tail[12]) << 32;
case 12:
k2 ^= (uint64_t)(tail[11]) << 24;
case 11:
k2 ^= (uint64_t)(tail[10]) << 16;
case 10:
k2 ^= (uint64_t)(tail[ 9]) << 8;
case 9:
k2 ^= (uint64_t)(tail[ 8]) << 0;
k2 *= c2;
k2 = ROTL64(k2, 33);
k2 *= c1;
c->h2 ^= k2;
case 8:
k1 ^= (uint64_t)(tail[ 7]) << 56;
case 7:
k1 ^= (uint64_t)(tail[ 6]) << 48;
case 6:
k1 ^= (uint64_t)(tail[ 5]) << 40;
case 5:
k1 ^= (uint64_t)(tail[ 4]) << 32;
case 4:
k1 ^= (uint64_t)(tail[ 3]) << 24;
case 3:
k1 ^= (uint64_t)(tail[ 2]) << 16;
case 2:
k1 ^= (uint64_t)(tail[ 1]) << 8;
case 1:
k1 ^= (uint64_t)(tail[ 0]) << 0;
k1 *= c1;
k1 = ROTL64(k1, 31);
k1 *= c2;
c->h1 ^= k1;
};
}
static void murmur3_finish_running_checksum(struct running_checksum *_c,
unsigned char *digest)
{
struct murmur3_running_checksum *c = rc_to_priv(_c);
checksum_tailing_data(c);
uint64_t h1 = c->h1;
uint64_t h2 = c->h2;
uint64_t len = c->len;
h1 ^= len;
h2 ^= len;
h1 += h2;
h2 += h1;
h1 = fmix64(h1);
h2 = fmix64(h2);
h1 += h2;
h2 += h1;
((uint64_t*)digest)[0] = h1;
((uint64_t*)digest)[1] = h2;
memset(&digest[digest_len], 0, DIGEST_LEN_MAX - digest_len);
free(c);
}
static void murmur3_checksum_block(char *buf, int len, unsigned char *digest)
{
struct running_checksum *csum = murmur3_start_running_checksum();
murmur3_add_to_running_checksum(csum, len, (unsigned char*)buf);
murmur3_finish_running_checksum(csum, digest);
}
static struct csum_module_ops ops_murmur3 = {
.init = murmur3_init_hash,
.checksum_block = murmur3_checksum_block,
.start_running_checksum = murmur3_start_running_checksum,
.add_to_running_checksum = murmur3_add_to_running_checksum,
.finish_running_checksum = murmur3_finish_running_checksum,
};
struct csum_module csum_module_murmur3 = {
.name = "murmur3",
.hash_type = HASH_TYPE_MURMUR3,
.ops = &ops_murmur3,
};
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