#include <stdint.h>
#include <string.h>
#include <assert.h>

static inline uint64_t
diffuse(uint64_t val)
{
  uint64_t a, b;
  val *= 0x6eed0e9da4d94a4fULL;
  //a = val >> 32;
  //b = val >> 60;
  //val ^= a >> b;
  val ^= (val << 17) | (val >> (64 - 17));
  val *= 0x6eed0e9da4d94a4fULL;
  return val;
}


void sea_hash_test(const void *key, int len, uint32_t seed, void *out) {
  uint64_t a, b, c, d;
  uint64_t s = seed;
  uint64_t *p;
  unsigned char pad[8] = {0};

  a = 0x16f11fe89b0d677cULL ^ s;
  b = 0xb480a793d8e6c86cULL;
  c = 0x6fe2e5aaf078ebc9ULL;
  d = 0x14f994a4c5259381ULL;

  p = (uint64_t *)key;
  while (len >= 32) {
    a ^= *p++;
    b ^= *p++;
    c ^= *p++;
    d ^= *p++;
    a = diffuse(a);
    b = diffuse(b);
    c = diffuse(c);
    d = diffuse(d);
    len -= 32;
  }

  switch (len) {
    case 25 ... 31:
      a ^= *p++;
      b ^= *p++;
      c ^= *p++;
      memcpy(pad, p, len - 24);
      d ^= *(uint64_t *)pad;
      a = diffuse(a);
      b = diffuse(b);
      c = diffuse(c);
      d = diffuse(d);
      break;
    case 24:
      a ^= *p++;
      b ^= *p++;
      c ^= *p++;
      a = diffuse(a);
      b = diffuse(b);
      c = diffuse(c);
      break;
    case 17 ... 23:
      a ^= *p++;
      b ^= *p++;
      memcpy(pad, p, len - 16);
      c ^= *(uint64_t *)pad;
      a = diffuse(a);
      b = diffuse(b);
      c = diffuse(c);
      break;
    case 16:
      a ^= *p++;
      b ^= *p++;
      a = diffuse(a);
      b = diffuse(b);
      break;
    case 9 ... 15:
      a ^= *p++;
      memcpy(pad, p, len - 8);
      b ^= *(uint64_t *)pad;
      a = diffuse(a);
      b = diffuse(b);
      break;
    case 8:
      a ^= *p++;
      a = diffuse(a);
      break;
    case 1 ... 7:
      memcpy(pad, p, len);
      a ^= *(uint64_t *)pad;
      a = diffuse(a);
      break;
    case 0:
      break;
    default:
      assert(0);
  }

  a ^= b;
  c ^= d;
  a ^= c;
  a ^= (uint64_t)len;
  uint64_t r = diffuse(a);
  memcpy(out, &r, 8);
}