4 ms·

PCG is incredibly simple as well. I made a 100 line with ~10sloc (most of it is comments). It too has a 128bit state and has a hard to beat speed for such a na

• loeg 6y ago
  > PCG is incredibly simple as well Yes and no. There are a lot of different functions in the PCG umbrella and that adds some mental complexity IMO. Some of the functions are very simple, including the 128-bit LCG I am referring to above ("pcg64_fast", IIRC). It is almost trivial; basically a single LoC to generate the next state and a single LoC to produce the output from that state: https://github.com/imneme/pcg-c/blob/master/include/pcg_variants.h#L2408 https://github.com/imneme/pcg-c/blob/master/include/pcg_vari... https://github.com/imneme/pcg-c/blob/master/include/pcg_variants.h#L2225-L2228 https://github.com/imneme/pcg-c/blob/master/include/pcg_vari... https://github.com/imneme/pcg-c/blob/master/include/pcg_variants.h#L618 https://github.com/imneme/pcg-c/blob/master/include/pcg_vari... https://github.com/imneme/pcg-c/blob/master/include/pcg_variants.h#L243 https://github.com/imneme/pcg-c/blob/master/include/pcg_vari... Or condensed from several composed inline functions: uint64_t my_pcg64_fast(uint128_t *state) { // Multiplier: (2549297995355413924ULL << 64) + 4865540595714422341ULL *state *= PCG_DEFAULT_MULTIPLIER_128; // Output is XOR-condensed state rotated right by the high 6 bits of state. return pcg_rotr_64(((uint64_t)(*state >> 64u)) ^ (uint64_t)*state, *state >> 122u); }