Mersenne Twister (32 and 64 bit) C89+ header

mt.h

#ifndef MT_H
#define MT_H

#define MT_GEN(TYPE, NAME, W, N, M, A, U, D, S, B, T, C, F, L, LM, UM) \
  typedef struct { \
    TYPE MT[N]; \
    TYPE index; \
  } NAME; \
  void NAME##_seed(NAME *mt, TYPE seed) { \
    mt->index = (N); \
    mt->MT[0] = seed; \
    int i; \
    for (i = 1; i < (N); i++) \
      mt->MT[i] = (F) * (mt->MT[i - 1] ^ mt->MT[i - 1] >> ((W) - 2)) + i; \
  } \
  void NAME##_twist(NAME *mt) { \
    static const TYPE a_lookup[] = {0, (A)}; \
    int i; \
    for (i = 0; i < (N); i++) { \
      TYPE x = (mt->MT[i] & (UM)) | \
                   (mt->MT[(i + 1) % (N)] & (LM)); \
      mt->MT[i] = mt->MT[(i + (M)) % (N)] ^ \
                  (x >> 1) ^ a_lookup[x & 1]; \
    } \
    mt->index = 0; \
  } \
  TYPE NAME##_rand(NAME *mt) { \
    if (mt->index >= (N)) \
      NAME##_twist(mt); \
    TYPE y = mt->MT[mt->index++]; \
    y ^= (y >> (U)) & (D); \
    y ^= (y << (S)) & (B); \
    y ^= (y << (T)) & (C); \
    return y ^ (y >> (L)); \
  }

MT_GEN(uint32_t, MT19937, 32, 624, 397, 0x9908b0df, 11, 0xffffffff, 7,
      0x9d2c5680, 15, 0xefc60000, 1812433253, 18, 0x7fffffff, 0x80000000)
MT_GEN(uint64_t, MT19937_64, 64, 312, 156, 0xb5026f5aa96619e9, 29,
      0x5555555555555555, 17, 0x71d67fffeda60000, 37, 0xfff7eee000000000,
      6364136223846793005, 43, 0x000000007fffffff, 0xffffffff80000000)

#undef MT_GEN

#endif