32-bit single state xorshift with mix

/*
  Experiemental versions of improving the stat properties of a 32-bit (for embedded devices) xorshift
  without restorting to adding state data. The two versions add one to the dependency chain.
  
  Based directly on the work of Sebastiano Vigna - http://xorshift.di.unimi.it/
*/


uint32_t state = 1;

// Off the shelf xorshift.
// failures from small crush
//    1  BirthdaySpacings
//    2  Collision
//    6  MaxOft
//    8  MatrixRank
//   10  RandomWalk1 H
// failures from small crush (bit reversed)
//   1  BirthdaySpacings
//   6  MaxOft
//   8  MatrixRank
//  10  RandomWalk1 H
//  10  RandomWalk1 M
//  10  RandomWalk1 J
//  10  RandomWalk1 R
//  10  RandomWalk1 C

uint32_t xorshift32(void)
{
  state ^= (state << 13);
  state ^= (state >> 17);
  state ^= (state <<  5);
  
  return state;
}

// Based on: Further scramblings of Marsaglia's xorshift generators.
// failures from small crush
//    1  BirthdaySpacings
// failures from small crush (bit reversed)
//    1  BirthdaySpacings
//    2  Collision
//    6  MaxOft

uint32_t xorshift32a(void)
{
  int s0  = state;
  state ^= (state << 13);
  state ^= (state >> 17);
  state ^= (state <<  5);

  return state + s0;
}

// Based on: An experimental exploration of Marsaglia's xorshift generators, scrambled
// failures from small crush
//   1  BirthdaySpacings
// failures from small crush (bit reversed)
//   1  BirthdaySpacings
//   6  MaxOft
uint32_t xorshift32m(void)
{
  state ^= (state << 13);
  state ^= (state >> 17);
  state ^= (state <<  5);

  return state*1597334677;
}