oxen-core/src/crypto/cn_turtle_hash-portable.inl

// Portable implementation as a fallback

static void (*const extra_hashes[4])(const void *, size_t, char *) = {
  hash_extra_blake, hash_extra_groestl, hash_extra_jh, hash_extra_skein
};

extern int aesb_single_round(const uint8_t *in, uint8_t*out, const uint8_t *expandedKey);
extern int aesb_pseudo_round(const uint8_t *in, uint8_t *out, const uint8_t *expandedKey);

static void mul(const uint8_t* a, const uint8_t* b, uint8_t* res) {
  uint64_t a0, b0;
  uint64_t hi, lo;

  a0 = SWAP64LE(((uint64_t*)a)[0]);
  b0 = SWAP64LE(((uint64_t*)b)[0]);
  lo = mul128(a0, b0, &hi);
  ((uint64_t*)res)[0] = SWAP64LE(hi);
  ((uint64_t*)res)[1] = SWAP64LE(lo);
}

static void sum_half_blocks(uint8_t* a, const uint8_t* b) {
  uint64_t a0, a1, b0, b1;

  a0 = SWAP64LE(((uint64_t*)a)[0]);
  a1 = SWAP64LE(((uint64_t*)a)[1]);
  b0 = SWAP64LE(((uint64_t*)b)[0]);
  b1 = SWAP64LE(((uint64_t*)b)[1]);
  a0 += b0;
  a1 += b1;
  ((uint64_t*)a)[0] = SWAP64LE(a0);
  ((uint64_t*)a)[1] = SWAP64LE(a1);
}
#define U64(x) ((uint64_t *) (x))

static void copy_block(uint8_t* dst, const uint8_t* src) {
  memcpy(dst, src, AES_BLOCK_SIZE);
}

static void swap_blocks(uint8_t *a, uint8_t *b){
  uint64_t t[2];
  U64(t)[0] = U64(a)[0];
  U64(t)[1] = U64(a)[1];
  U64(a)[0] = U64(b)[0];
  U64(a)[1] = U64(b)[1];
  U64(b)[0] = U64(t)[0];
  U64(b)[1] = U64(t)[1];
}

static void xor_blocks(uint8_t* a, const uint8_t* b) {
  size_t i;
  for (i = 0; i < AES_BLOCK_SIZE; i++) {
    a[i] ^= b[i];
  }
}

static void xor64(uint8_t* left, const uint8_t* right)
{
  size_t i;
  for (i = 0; i < 8; ++i)
  {
    left[i] ^= right[i];
  }
}

#pragma pack(push, 1)
union cn_turtle_hash_state {
  union hash_state hs;
  struct {
    uint8_t k[64];
    uint8_t init[INIT_SIZE_BYTE];
  };
};
#pragma pack(pop)

void cn_turtle_hash(const void *data, size_t length, char *hash, int light, int variant, int prehashed, uint32_t scratchpad, uint32_t iterations)
{
  uint32_t init_rounds = (scratchpad / INIT_SIZE_BYTE);
  uint32_t aes_rounds = (iterations / 2);
  size_t TOTALBLOCKS = (CN_TURTLE_PAGE_SIZE / AES_BLOCK_SIZE);
  size_t lightFlag = (light ? 2: 1);

#ifndef FORCE_USE_HEAP
  uint8_t long_state[CN_TURTLE_PAGE_SIZE];
#else
#warning "ACTIVATING FORCE_USE_HEAP IN portable slow-hash.c"
  uint8_t *long_state = (uint8_t *)malloc(CN_TURTLE_PAGE_SIZE);
#endif

  union cn_turtle_hash_state state;
  uint8_t text[INIT_SIZE_BYTE];
  uint8_t a[AES_BLOCK_SIZE];
  uint8_t b[AES_BLOCK_SIZE * 2];
  uint8_t c1[AES_BLOCK_SIZE];
  uint8_t c2[AES_BLOCK_SIZE];
  uint8_t d[AES_BLOCK_SIZE];
  size_t i, j;
  uint8_t aes_key[AES_KEY_SIZE];
  uint8_t expandedKey[AES_EXPANDED_KEY_SIZE];

  if (prehashed) {
    memcpy(&state.hs, data, length);
  } else {
    hash_process(&state.hs, data, length);
  }
  memcpy(text, state.init, INIT_SIZE_BYTE);
  memcpy(aes_key, state.hs.b, AES_KEY_SIZE);

  VARIANT1_PORTABLE_INIT();
  VARIANT2_PORTABLE_INIT();

  oaes_expand_key_256(aes_key, expandedKey);
  for (i = 0; i < init_rounds; i++) {
    for (j = 0; j < INIT_SIZE_BLK; j++) {
      aesb_pseudo_round(&text[AES_BLOCK_SIZE * j], &text[AES_BLOCK_SIZE * j], expandedKey);
    }
    memcpy(&long_state[i * INIT_SIZE_BYTE], text, INIT_SIZE_BYTE);
  }

  for (i = 0; i < AES_BLOCK_SIZE; i++) {
    a[i] = state.k[     i] ^ state.k[AES_BLOCK_SIZE * 2 + i];
    b[i] = state.k[AES_BLOCK_SIZE + i] ^ state.k[AES_BLOCK_SIZE * 3 + i];
  }

  for (i = 0; i < aes_rounds; i++) {
    /* Dependency chain: address -> read value ------+
     * written value <-+ hard function (AES or MUL) <+
     * next address  <-+
     */
    /* Iteration 1 */
    #define state_index(x,div) (((*((uint64_t *)x) >> 4) & (TOTALBLOCKS /(div) - 1)) << 4)
    j = state_index(a, lightFlag);
    copy_block(c1, &long_state[j]);
    aesb_single_round(c1, c1, a);

    VARIANT2_PORTABLE_SHUFFLE_ADD(long_state, j);
    copy_block(&long_state[j], c1);
    xor_blocks(&long_state[j], b);
    VARIANT1_1(&long_state[j]);

    /* Iteration 2 */
    j = state_index(c1, lightFlag);
    copy_block(c2, &long_state[j]);
    VARIANT2_PORTABLE_INTEGER_MATH(c2, c1);
    mul(c1, c2, d);
    VARIANT2_2_PORTABLE();
    VARIANT2_PORTABLE_SHUFFLE_ADD(long_state, j);
    swap_blocks(a, c1);
    sum_half_blocks(c1, d);
    swap_blocks(c1, c2);
    xor_blocks(c1, c2);
    VARIANT1_2(c2 + 8);
    copy_block(&long_state[j], c2);

    if (variant == 2) {
      copy_block(b + AES_BLOCK_SIZE, b);
    }
    copy_block(b, a);
    copy_block(a, c1);
  }

  memcpy(text, state.init, INIT_SIZE_BYTE);
  oaes_expand_key_256(&state.hs.b[32], expandedKey);
  for (i = 0; i < init_rounds; i++) {
    for (j = 0; j < INIT_SIZE_BLK; j++) {
      xor_blocks(&text[j * AES_BLOCK_SIZE], &long_state[i * INIT_SIZE_BYTE + j * AES_BLOCK_SIZE]);
      aesb_pseudo_round(&text[AES_BLOCK_SIZE * j], &text[AES_BLOCK_SIZE * j], expandedKey);
    }
  }
  memcpy(state.init, text, INIT_SIZE_BYTE);
  hash_permutation(&state.hs);
  /*memcpy(hash, &state, 32);*/
  extra_hashes[state.hs.b[0] & 3](&state, 200, hash);

#ifdef FORCE_USE_HEAP
  free(long_state);
#endif
}