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RealNeGate/mur.c Secret

Created November 8, 2023 02:04
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#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/stat.h>
#ifdef _WIN32
#define fileno _fileno
#define fstat _fstat
#define stat _stat
#endif
static char* read_entire_file(const char* filepath, size_t* out_length) {
FILE* file = fopen(filepath, "rb");
if (file == NULL) {
return NULL;
}
int descriptor = fileno(file);
struct stat file_stats;
if (fstat(descriptor, &file_stats) == -1) {
return NULL;
}
int length = file_stats.st_size;
char* data = malloc(length + 1);
fseek(file, 0, SEEK_SET);
size_t length_read = fread(data, 1, length, file);
data[length_read] = '\0';
fclose(file);
*out_length = length_read;
return data;
}
uint32_t murmur3_32(const void* key, size_t len) {
uint32_t h = 0;
// main body, work on 32-bit blocks at a time
for (size_t i=0;i<len/4;i++) {
uint32_t k = ((uint32_t*) key)[i];
// memcpy(&k, &key[i * 4], sizeof(k));
k *= 0xcc9e2d51;
k = ((k << 15) | (k >> 17))*0x1b873593;
h = (((h^k) << 13) | ((h^k) >> 19))*5 + 0xe6546b64;
}
// load/mix up to 3 remaining tail bytes into a tail block
uint32_t t = 0;
const uint8_t *tail = ((const uint8_t*) key) + 4*(len/4);
switch(len & 3) {
case 3: t ^= tail[2] << 16;
case 2: t ^= tail[1] << 8;
case 1: {
t ^= tail[0] << 0;
h ^= ((0xcc9e2d51*t << 15) | (0xcc9e2d51*t >> 17))*0x1b873593;
}
}
// finalization mix, including key length
h = ((h^len) ^ ((h^len) >> 16))*0x85ebca6b;
h = (h ^ (h >> 13))*0xc2b2ae35;
return (h ^ (h >> 16));
}
int main(int argc, char** argv) {
size_t len;
void* data = read_entire_file(argv[1], &len);
printf("Wack! %#x\n", murmur3_32(data, len));
return 0;
}
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