c_cpp 哈希的新方法称为炉哈希

Posted 2021-05-14

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
// Prototype for furnace hashing


#define FURNACE_INIT(furn, start) \
                  furn.value = start; \
                  furn.state = 0; \
                  furn.sections = (uint8_t*)(&(furn.value))

// Debug macro
#define FURNACE_PRINT(furn) printf("furnace value %u\nfurance sections: %u %u %u %u\n", furn.value, furn.sections[0], furn.sections[1], furn.sections[2], furn.sections[3])

// The melting operation XOR's a 8-bit input to a section of the base value, essentially melting it
#define FURNACE_MELT(furn, byte) \
               furn.sections[furn.state] ^= byte; \
               furn.state = (furn.state + 1) % 4

typedef struct
{
  uint32_t value;
  uint8_t* sections;
  int state;
} furnace_t;

void furnace_run(void)
{
  furnace_t foo;
  FURNACE_INIT(foo, 5);
  FURNACE_PRINT(foo);
  FURNACE_MELT(foo, 0xfa);
  FURNACE_PRINT(foo);
  FURNACE_MELT(foo, 0xfa);
  FURNACE_PRINT(foo);
}

void furnace_hash(const char* data)
{
  const unsigned char* reader = (const unsigned char*)data;
  furnace_t foo;
  FURNACE_INIT(foo, 17);
  while(*reader)
  {
    FURNACE_PRINT(foo);
    FURNACE_MELT(foo, (*reader));
    reader++;
  }
  FURNACE_PRINT(foo);
}

int main(void) {
  furnace_hash("Hello! World leaders!!");
  return 0;
}