#include <stdbool.h>
#include <stdint.h>

static uint32_t
rotr_32 (uint32_t x, int c)
{
  return (x >> c) | (x << (32 - c));
}

static uint64_t
rotr_64 (uint64_t x, int c)
{
  return (x >> c) | (x << (64 - c));
}

static uint32_t
from_be32 (const uint8_t *x)
{
  uint32_t u = 0;
  for (unsigned int i = 0; i < 4; ++i)
    {
      u <<= 8;
      u |= x[i];
    }
  return u;
}

static void
to_be32 (uint32_t u, uint8_t *x)
{
  for (unsigned int i = 0; i < 4; ++i)
    {
      x[3 - i] = u & 0xFF;
      u >>= 8;
    }
}

static uint64_t
from_be64 (const uint8_t *x)
{
  uint64_t u = 0;
  for (unsigned int i = 0; i < 8; ++i)
    {
      u <<= 8;
      u |= x[i];
    }
  return u;
}

static void
to_be64 (uint64_t u, uint8_t *x)
{
  for (unsigned int i = 0; i < 8; ++i)
    {
      x[7 - i] = u & 0xFF;
      u >>= 8;
    }
}

static uint32_t K256[64] = {
  0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1,
  0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
  0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786,
  0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
  0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147,
  0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
  0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b,
  0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
  0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a,
  0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
  0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
};

void
tct_sha256 (const uint8_t *data, uint64_t data_len, uint8_t *hash_out)
{
  uint8_t chunk[64];
  uint32_t w[64];
  uint32_t hash_internal[8] = {
    0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
    0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19,
  };
  for (uint64_t i = 0; i < data_len + 9; i += 64)
    {
      // Handle possible negatives properly
      uint64_t chunk_size
          = (data_len + 9 - i < 64) ? ((data_len + 65 - i) % 64) : 64;
      for (unsigned int j = 0; j < 64; ++j)
        {
          chunk[j] = 0x0;
        }
      for (unsigned int j = 0; j < chunk_size; ++j)
        {
          if (i + j < data_len)
            {
              chunk[j] = data[i + j];
            }
          else if (i + j < data_len + 1)
            {
              chunk[j] = 0x80;
            }
        }
      if (data_len + 9 - i <= 64)
        {
          to_be64 (data_len * 8, chunk + 56);
        }
      for (unsigned int j = 0; j < 16; ++j)
        {
          w[j] = from_be32 (chunk + j * 4);
        }
      for (unsigned int j = 16; j < 64; ++j)
        {
          uint32_t s0 = rotr_32 (w[j - 15], 7) ^ rotr_32 (w[j - 15], 18)
                        ^ (w[j - 15] >> 3);
          uint32_t s1 = rotr_32 (w[j - 2], 17) ^ rotr_32 (w[j - 2], 19)
                        ^ (w[j - 2] >> 10);
          w[j] = w[j - 16] + s0 + w[j - 7] + s1;
        }
      uint32_t a = hash_internal[0], b = hash_internal[1],
               c = hash_internal[2], d = hash_internal[3],
               e = hash_internal[4], f = hash_internal[5],
               g = hash_internal[6], k = hash_internal[7];
      for (unsigned int j = 0; j < 64; ++j)
        {
          uint32_t S1 = rotr_32 (e, 6) ^ rotr_32 (e, 11) ^ rotr_32 (e, 25);
          uint32_t ch = (e & f) ^ ((~e) & g);
          uint32_t temp1 = k + S1 + ch + K256[j] + w[j];
          uint32_t S0 = rotr_32 (a, 2) ^ rotr_32 (a, 13) ^ rotr_32 (a, 22);
          uint32_t maj = (a & b) ^ (a & c) ^ (b & c);
          uint32_t temp2 = S0 + maj;
          k = g;
          g = f;
          f = e;
          e = d + temp1;
          d = c;
          c = b;
          b = a;
          a = temp1 + temp2;
        }
      hash_internal[0] += a;
      hash_internal[1] += b;
      hash_internal[2] += c;
      hash_internal[3] += d;
      hash_internal[4] += e;
      hash_internal[5] += f;
      hash_internal[6] += g;
      hash_internal[7] += k;
    }
  for (unsigned int i = 0; i < 8; ++i)
    {
      to_be32 (hash_internal[i], hash_out + i * 4);
    }
}

static uint64_t K512[80] = {
  0x428a2f98d728ae22, 0x7137449123ef65cd, 0xb5c0fbcfec4d3b2f,
  0xe9b5dba58189dbbc, 0x3956c25bf348b538, 0x59f111f1b605d019,
  0x923f82a4af194f9b, 0xab1c5ed5da6d8118, 0xd807aa98a3030242,
  0x12835b0145706fbe, 0x243185be4ee4b28c, 0x550c7dc3d5ffb4e2,
  0x72be5d74f27b896f, 0x80deb1fe3b1696b1, 0x9bdc06a725c71235,
  0xc19bf174cf692694, 0xe49b69c19ef14ad2, 0xefbe4786384f25e3,
  0x0fc19dc68b8cd5b5, 0x240ca1cc77ac9c65, 0x2de92c6f592b0275,
  0x4a7484aa6ea6e483, 0x5cb0a9dcbd41fbd4, 0x76f988da831153b5,
  0x983e5152ee66dfab, 0xa831c66d2db43210, 0xb00327c898fb213f,
  0xbf597fc7beef0ee4, 0xc6e00bf33da88fc2, 0xd5a79147930aa725,
  0x06ca6351e003826f, 0x142929670a0e6e70, 0x27b70a8546d22ffc,
  0x2e1b21385c26c926, 0x4d2c6dfc5ac42aed, 0x53380d139d95b3df,
  0x650a73548baf63de, 0x766a0abb3c77b2a8, 0x81c2c92e47edaee6,
  0x92722c851482353b, 0xa2bfe8a14cf10364, 0xa81a664bbc423001,
  0xc24b8b70d0f89791, 0xc76c51a30654be30, 0xd192e819d6ef5218,
  0xd69906245565a910, 0xf40e35855771202a, 0x106aa07032bbd1b8,
  0x19a4c116b8d2d0c8, 0x1e376c085141ab53, 0x2748774cdf8eeb99,
  0x34b0bcb5e19b48a8, 0x391c0cb3c5c95a63, 0x4ed8aa4ae3418acb,
  0x5b9cca4f7763e373, 0x682e6ff3d6b2b8a3, 0x748f82ee5defb2fc,
  0x78a5636f43172f60, 0x84c87814a1f0ab72, 0x8cc702081a6439ec,
  0x90befffa23631e28, 0xa4506cebde82bde9, 0xbef9a3f7b2c67915,
  0xc67178f2e372532b, 0xca273eceea26619c, 0xd186b8c721c0c207,
  0xeada7dd6cde0eb1e, 0xf57d4f7fee6ed178, 0x06f067aa72176fba,
  0x0a637dc5a2c898a6, 0x113f9804bef90dae, 0x1b710b35131c471b,
  0x28db77f523047d84, 0x32caab7b40c72493, 0x3c9ebe0a15c9bebc,
  0x431d67c49c100d4c, 0x4cc5d4becb3e42b6, 0x597f299cfc657e2a,
  0x5fcb6fab3ad6faec, 0x6c44198c4a475817,
};

void
tct_sha512 (const uint8_t *data, uint64_t data_len, uint8_t *hash_out)
{
  uint8_t chunk[128];
  uint64_t w[80];
  uint64_t hash_internal[8] = {
    0x6a09e667f3bcc908, 0xbb67ae8584caa73b, 0x3c6ef372fe94f82b,
    0xa54ff53a5f1d36f1, 0x510e527fade682d1, 0x9b05688c2b3e6c1f,
    0x1f83d9abfb41bd6b, 0x5be0cd19137e2179,
  };
  for (uint64_t i = 0; i < data_len + 17; i += 128)
    {
      // Handle possible negatives properly
      uint64_t chunk_size
          = (data_len + 17 - i < 128) ? ((data_len + 129 - i) % 128) : 128;
      for (unsigned int j = 0; j < 128; ++j)
        {
          chunk[j] = 0x0;
        }
      for (unsigned int j = 0; j < chunk_size; ++j)
        {
          if (i + j < data_len)
            {
              chunk[j] = data[i + j];
            }
          else if (i + j < data_len + 1)
            {
              chunk[j] = 0x80;
            }
        }
      if (data_len + 17 - i <= 128)
        {
          to_be64 (data_len * 8, chunk + 120);
        }
      for (unsigned int j = 0; j < 16; ++j)
        {
          w[j] = from_be64 (chunk + j * 8);
        }
      for (unsigned int j = 16; j < 80; ++j)
        {
          uint64_t s0 = rotr_64 (w[j - 15], 1) ^ rotr_64 (w[j - 15], 8)
                        ^ (w[j - 15] >> 7);
          uint64_t s1 = rotr_64 (w[j - 2], 19) ^ rotr_64 (w[j - 2], 61)
                        ^ (w[j - 2] >> 6);
          w[j] = w[j - 16] + s0 + w[j - 7] + s1;
        }
      uint64_t a = hash_internal[0], b = hash_internal[1],
               c = hash_internal[2], d = hash_internal[3],
               e = hash_internal[4], f = hash_internal[5],
               g = hash_internal[6], k = hash_internal[7];
      for (unsigned int j = 0; j < 80; ++j)
        {
          uint64_t S1 = rotr_64 (e, 14) ^ rotr_64 (e, 18) ^ rotr_64 (e, 41);
          uint64_t ch = (e & f) ^ ((~e) & g);
          uint64_t temp1 = k + S1 + ch + K512[j] + w[j];
          uint64_t S0 = rotr_64 (a, 28) ^ rotr_64 (a, 34) ^ rotr_64 (a, 39);
          uint64_t maj = (a & b) ^ (a & c) ^ (b & c);
          uint64_t temp2 = S0 + maj;
          k = g;
          g = f;
          f = e;
          e = d + temp1;
          d = c;
          c = b;
          b = a;
          a = temp1 + temp2;
        }
      hash_internal[0] += a;
      hash_internal[1] += b;
      hash_internal[2] += c;
      hash_internal[3] += d;
      hash_internal[4] += e;
      hash_internal[5] += f;
      hash_internal[6] += g;
      hash_internal[7] += k;
    }
  for (unsigned int i = 0; i < 8; ++i)
    {
      to_be64 (hash_internal[i], hash_out + i * 8);
    }
}