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jweinst1/density.cpp

Last active August 5, 2025 23:38
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density.cpp
#include <stdint.h>
#include <stddef.h>
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <stdbool.h>
#include <unordered_map>
#include <vector>
static std::unordered_map<uint64_t, size_t> GLOBAL_HASH_COUNT;
static void addHash(uint64_t h) {
auto found = GLOBAL_HASH_COUNT.find(h);
if (found != GLOBAL_HASH_COUNT.end()) {
found->second += 1;
} else {
GLOBAL_HASH_COUNT.insert(std::make_pair(h, 1));
}
}
static size_t printColls() {
size_t total = 0;
for (const auto& elem: GLOBAL_HASH_COUNT) {
if (elem.second > 1) {
printf("COLL: %llu = %zu\n", elem.first, elem.second);
total += (elem.second - 1);
}
}
printf("TOTAL COLL: %zu\n", total);
return total;
}
// Finalization mix - force all bits of a hash block to avalanche
static uint64_t fmix64(uint64_t k) {
k ^= k >> 33;
k *= 0xff51afd7ed558ccdULL;
k ^= k >> 33;
k *= 0xc4ceb9fe1a85ec53ULL;
k ^= k >> 33;
return k;
}
uint64_t murmur3_64(const void *key, size_t len, uint32_t seed) {
const uint8_t *data = (const uint8_t *)key;
const int nblocks = len / 16;
uint64_t h1 = seed;
uint64_t h2 = seed;
const uint64_t c1 = 0x87c37b91114253d5ULL;
const uint64_t c2 = 0x4cf5ad432745937fULL;
//----------
// body
const uint64_t *blocks = (const uint64_t *)(data);
for (int i = 0; i < nblocks; i++) {
uint64_t k1 = blocks[i * 2 + 0];
uint64_t k2 = blocks[i * 2 + 1];
k1 *= c1; k1 = (k1 << 31) | (k1 >> (64 - 31)); k1 *= c2; h1 ^= k1;
h1 = (h1 << 27) | (h1 >> (64 - 27)); h1 += h2; h1 = h1 * 5 + 0x52dce729;
k2 *= c2; k2 = (k2 << 33) | (k2 >> (64 - 33)); k2 *= c1; h2 ^= k2;
h2 = (h2 << 31) | (h2 >> (64 - 31)); h2 += h1; h2 = h2 * 5 + 0x38495ab5;
}
//----------
// tail
const uint8_t *tail = (const uint8_t *)(data + nblocks * 16);
uint64_t k1 = 0;
uint64_t k2 = 0;
switch (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 = (k2 << 33) | (k2 >> (64 - 33)); k2 *= c1; 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 = (k1 << 31) | (k1 >> (64 - 31)); k1 *= c2; h1 ^= k1;
}
//----------
// finalization
h1 ^= len;
h2 ^= len;
h1 += h2;
h2 += h1;
h1 = fmix64(h1);
h2 = fmix64(h2);
h1 += h2;
// Return 64-bit hash (can return h2 or h1 depending on needs)
return h1;
}
void create_rand_hashes(std::vector<uint64_t>& hashes, size_t count, size_t* modder) {
static const size_t input_size = 10;
char input_string[input_size + 1] = {'\0'};
for (size_t i = 0; i < count; ++i) {
for (int j = 0; j < input_size; ++j)
{
input_string[j] = rand() % 253;
}
if (modder != NULL) {
hashes.push_back(murmur3_64(input_string, input_size, input_size) % *modder);
} else {
hashes.push_back(murmur3_64(input_string, input_size, input_size));
}
}
}
struct HashBlock {
size_t hash_count;
std::vector<uint64_t> hashes;
HashBlock() {
hash_count = 0;
}
explicit HashBlock(size_t count, size_t mod = 0): hash_count(count) {
create_rand_hashes(hashes, hash_count, mod == 0 ? NULL : &mod);
for (const auto& h : hashes) {
addHash(h);
}
}
};
int main(int argc, char const *argv[])
{
srand(time(NULL));
std::vector<HashBlock> blocks;
for (int i = 0; i < 100; ++i)
{
HashBlock h(500, 1024 * 1024 * 10);
blocks.push_back(h);
}
printColls();
return 0;
}
Raw
hash_density_research.c
#include <stdint.h>
#include <stddef.h>
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <stdbool.h>
// Finalization mix - force all bits of a hash block to avalanche
static uint64_t fmix64(uint64_t k) {
k ^= k >> 33;
k *= 0xff51afd7ed558ccdULL;
k ^= k >> 33;
k *= 0xc4ceb9fe1a85ec53ULL;
k ^= k >> 33;
return k;
}
uint64_t murmur3_64(const void *key, size_t len, uint32_t seed) {
const uint8_t *data = (const uint8_t *)key;
const int nblocks = len / 16;
uint64_t h1 = seed;
uint64_t h2 = seed;
const uint64_t c1 = 0x87c37b91114253d5ULL;
const uint64_t c2 = 0x4cf5ad432745937fULL;
//----------
// body
const uint64_t *blocks = (const uint64_t *)(data);
for (int i = 0; i < nblocks; i++) {
uint64_t k1 = blocks[i * 2 + 0];
uint64_t k2 = blocks[i * 2 + 1];
k1 *= c1; k1 = (k1 << 31) | (k1 >> (64 - 31)); k1 *= c2; h1 ^= k1;
h1 = (h1 << 27) | (h1 >> (64 - 27)); h1 += h2; h1 = h1 * 5 + 0x52dce729;
k2 *= c2; k2 = (k2 << 33) | (k2 >> (64 - 33)); k2 *= c1; h2 ^= k2;
h2 = (h2 << 31) | (h2 >> (64 - 31)); h2 += h1; h2 = h2 * 5 + 0x38495ab5;
}
//----------
// tail
const uint8_t *tail = (const uint8_t *)(data + nblocks * 16);
uint64_t k1 = 0;
uint64_t k2 = 0;
switch (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 = (k2 << 33) | (k2 >> (64 - 33)); k2 *= c1; 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 = (k1 << 31) | (k1 >> (64 - 31)); k1 *= c2; h1 ^= k1;
}
//----------
// finalization
h1 ^= len;
h2 ^= len;
h1 += h2;
h2 += h1;
h1 = fmix64(h1);
h2 = fmix64(h2);
h1 += h2;
// Return 64-bit hash (can return h2 or h1 depending on needs)
return h1;
}
struct number_node {
uint64_t hash;
uint64_t block;
};
struct number_part {
size_t size;
};
uint64_t* create_rand_hashes(size_t count) {
uint64_t* hashes = malloc(count * sizeof(uint64_t));
static const size_t input_size = 10;
char input_string[input_size + 1] = {'\0'};
for (size_t i = 0; i < count; ++i) {
for (int j = 0; j < input_size; ++j)
{
input_string[j] = rand() % 253;
}
hashes[i] = murmur3_64(input_string, input_size, input_size) % 9999999999;
}
return hashes;
}
bool find_min_max(const uint64_t *array, size_t size, uint64_t *min_out, uint64_t *max_out) {
if (size == 0 || array == NULL || min_out == NULL || max_out == NULL) {
return false; // Invalid input
}
uint64_t min = UINT64_MAX;
uint64_t max = 0;
for (size_t i = 0; i < size; ++i) {
if (array[i] < min) min = array[i];
if (array[i] > max) max = array[i];
}
*min_out = min;
*max_out = max;
return true;
}
struct num_range {
uint64_t min;
uint64_t max;
};
static inline uint64_t min_u64(uint64_t a, uint64_t b) {
return a < b ? a : b;
}
static inline uint64_t max_u64(uint64_t a, uint64_t b) {
return a > b ? a : b;
}
uint64_t line_overlap_amount(uint64_t a1, uint64_t a2, uint64_t b1, uint64_t b2) {
// Normalize segments
if (a1 > a2) {
uint64_t tmp = a1; a1 = a2; a2 = tmp;
}
if (b1 > b2) {
uint64_t tmp = b1; b1 = b2; b2 = tmp;
}
uint64_t start = max_u64(a1, b1);
uint64_t end = min_u64(a2, b2);
if (start >= end) {
return 0; // No overlap
}
return end - start;
}
int main(int argc, char const *argv[])
{
srand(time(NULL));
static const size_t repeats = 20;
struct num_range* rngs = malloc(repeats * sizeof(struct num_range));
for (int k = 0; k < repeats; ++k)
{
uint64_t* hs = create_rand_hashes(50);
uint64_t mini = 0;
uint64_t maxi = 0;
find_min_max(hs, 50, &mini, &maxi);
printf("MIN: %llu , MAX: %llu RNG: %llu FACT: %llu\n", mini, maxi, maxi - mini, (maxi - mini) / 64000);
rngs[k].min = mini;
rngs[k].max = maxi;
free(hs);
}
for (int i = 0; i < repeats; ++i)
{
for (int j = i + 1; j < repeats; ++j)
{
printf("Pos1: %d Pos2: %d, Overlap: %llu\n", i, j, line_overlap_amount(rngs[i].min, rngs[i].max, rngs[j].min, rngs[j].max));
}
}
free(rngs);
return 0;
}
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