On Friday, December 8, 2017 at 5:53:22 PM UTC+1, M.M. wrote:
> On Thursday, December 7, 2017 at 1:10:25 AM UTC+1, AK wrote:
> > Użytkownik "slawek" <f...@f...com> napisał:
> > >> rand() & 0xFF // ;)
> > >
> > > Lepiej (rand() >> 4) & 0xff
> > >
> > > Najniższe bity wywalić.
> >
> > To prawda, ale oni chcieli "szybciej", a nie "lepiej" :)
> > PS: Oczywiscie generalnie to byl zart (no nie tak znow w 100%:)
> >
> > AK
>
> Generator Fibonacciego też można napisać w 10 minut na
> kolanie i, jak na razie, przeszedł kilkanaście początkowych
> diehardera nawet na m=30. Generowanie liczb jest ekstremalnie
> szybkie, nie zawiera nawet ifa. Niestety nie wiadomo czy dla
> innych zarodków też zachowa się tak samo dobrze :/ I drugie
> niestety: poniższa implementacja wymaga ponad 16k bajtów ram.
>
> Kod:
> class FibRnd {
> private:
> unsigned int a,b,c;
> unsigned int *x;
> unsigned int max;
>
> public:
> FibRnd(unsigned int seed) {
> max = 1<<12;
> a = 0;
> b = 16;
> c = max-1;
> x = new unsigned int[max];
> for( unsigned int i=0 ; i<max * 4 ; i++ ) {
> x[i%max] <<= 4;
> x[i%max] ^= seed = ((seed * 359ull + 3733ull) % 1057767ull);
> }
> }
> ~FibRnd() {
> delete[] x;
> }
> unsigned int operator ()() {
> a = (a+1)&(max-1);
> b = (b+1)&(max-1);
> c = (c+1)&(max-1);
> return x[c] = x[a] + x[b];
> }
>
> };
>
> int main( int argc, char *argv[] ) {
> FibRnd rnd((unsigned int)time(NULL));
> while( true ) {
> unsigned char x[N];
> for( int i=0 ; i<N ; i++ )
> x[i] = (unsigned char)rnd();
> fwrite( x , 1 , N , stdout );
> }
> return 0;
> }

Całego diehardera przeszedł na m=30. Nie wiadomo czy dla innych zarodków też
przejdzie, ale jak generator nie musi być super równomierny, a ma być
bardzo szybki, to chyba nie ma nic lepszego.


Generator zwraca tylko 8 najmłodszych bitów. Ciekawe czy działałby lepiej,
gdyby zwracał 8 innych bitów niż najstarsze, bo na wydajność to praktycznie
by nie wpłynęło. Generator może też zwracać więcej bitów, np. 16 bitów, lub 32 bity,
a jakby go zaimplementować na typie uint64 lub uint128, to mógłby
zwracać 64 lub 128 bitów. Przyspieszyłoby go to jeszcze do 16 razy. Jak
myślicie, jakość generowanych liczb by spadła?


Wyniki testu dla 8 najmłodszych bitów:

time ./frnd | dieharder -a -m 30 -g 200
#===================================================
==========================#
# dieharder version 3.31.1 Copyright 2003 Robert G. Brown #
#===================================================
==========================#
rng_name |rands/second| Seed |
stdin_input_raw| 3.00e+07 |2482448351|
#===================================================
==========================#
test_name |ntup| tsamples |psamples| p-value |Assessment
#===================================================
==========================#
diehard_birthdays| 0| 100| 3000|0.29234458| PASSED
diehard_operm5| 0| 1000000| 3000|0.51398474| PASSED
diehard_rank_32x32| 0| 40000| 3000|0.36767415| PASSED
diehard_rank_6x8| 0| 100000| 3000|0.69227346| PASSED
diehard_bitstream| 0| 2097152| 3000|0.30960016| PASSED
diehard_opso| 0| 2097152| 3000|0.85888419| PASSED
diehard_oqso| 0| 2097152| 3000|0.67207083| PASSED
diehard_dna| 0| 2097152| 3000|0.00012554| WEAK
diehard_count_1s_str| 0| 256000| 3000|0.51597335| PASSED
diehard_count_1s_byt| 0| 256000| 3000|0.26197695| PASSED
diehard_parking_lot| 0| 12000| 3000|0.17469806| PASSED
diehard_2dsphere| 2| 8000| 3000|0.54418532| PASSED
diehard_3dsphere| 3| 4000| 3000|0.87789531| PASSED
diehard_squeeze| 0| 100000| 3000|0.26815462| PASSED
diehard_sums| 0| 100| 3000|0.00000000| FAILED
diehard_runs| 0| 100000| 3000|0.01445376| PASSED
diehard_runs| 0| 100000| 3000|0.00537657| PASSED
diehard_craps| 0| 200000| 3000|0.93729302| PASSED
diehard_craps| 0| 200000| 3000|0.34274658| PASSED
marsaglia_tsang_gcd| 0| 10000000| 3000|0.83716130| PASSED
marsaglia_tsang_gcd| 0| 10000000| 3000|0.05530917| PASSED
sts_monobit| 1| 100000| 3000|0.85138074| PASSED
sts_runs| 2| 100000| 3000|0.44074715| PASSED
sts_serial| 1| 100000| 3000|0.21861505| PASSED



sts_serial| 2| 100000| 3000|0.28454007| PASSED



sts_serial| 3| 100000| 3000|0.61438900| PASSED



sts_serial| 3| 100000| 3000|0.22112971| PASSED



sts_serial| 4| 100000| 3000|0.95517930| PASSED



sts_serial| 4| 100000| 3000|0.16562539| PASSED



sts_serial| 5| 100000| 3000|0.28466376| PASSED



sts_serial| 5| 100000| 3000|0.10776582| PASSED



sts_serial| 6| 100000| 3000|0.45920174| PASSED



sts_serial| 6| 100000| 3000|0.20303651| PASSED



sts_serial| 7| 100000| 3000|0.49722161| PASSED



sts_serial| 7| 100000| 3000|0.80685114| PASSED



sts_serial| 8| 100000| 3000|0.41749281| PASSED
sts_serial| 8| 100000| 3000|0.94116829| PASSED
sts_serial| 9| 100000| 3000|0.53222747| PASSED
sts_serial| 9| 100000| 3000|0.58938752| PASSED
sts_serial| 10| 100000| 3000|0.26245753| PASSED
sts_serial| 10| 100000| 3000|0.44889624| PASSED
sts_serial| 11| 100000| 3000|0.02441041| PASSED
sts_serial| 11| 100000| 3000|0.00181544| WEAK
sts_serial| 12| 100000| 3000|0.04469190| PASSED
sts_serial| 12| 100000| 3000|0.15885960| PASSED
sts_serial| 13| 100000| 3000|0.02979468| PASSED
sts_serial| 13| 100000| 3000|0.77864508| PASSED
sts_serial| 14| 100000| 3000|0.00025286| WEAK
sts_serial| 14| 100000| 3000|0.03756306| PASSED
sts_serial| 15| 100000| 3000|0.01495578| PASSED
sts_serial| 15| 100000| 3000|0.25646264| PASSED
sts_serial| 16| 100000| 3000|0.10219212| PASSED
sts_serial| 16| 100000| 3000|0.49916583| PASSED
rgb_bitdist| 1| 100000| 3000|0.24353012| PASSED
rgb_bitdist| 2| 100000| 3000|0.33193645| PASSED
rgb_bitdist| 3| 100000| 3000|0.77606973| PASSED
rgb_bitdist| 4| 100000| 3000|0.48072339| PASSED
rgb_bitdist| 5| 100000| 3000|0.02841032| PASSED
rgb_bitdist| 6| 100000| 3000|0.72828838| PASSED
rgb_bitdist| 7| 100000| 3000|0.06921169| PASSED
rgb_bitdist| 8| 100000| 3000|0.41825331| PASSED
rgb_bitdist| 9| 100000| 3000|0.91108880| PASSED
rgb_bitdist| 10| 100000| 3000|0.43222942| PASSED
rgb_bitdist| 11| 100000| 3000|0.61747840| PASSED
rgb_bitdist| 12| 100000| 3000|0.30358537| PASSED
rgb_minimum_distance| 2| 10000| 30000|0.04817726| PASSED



rgb_minimum_distance| 3| 10000| 30000|0.83114815| PASSED



rgb_minimum_distance| 4| 10000| 30000|0.00560345| PASSED



rgb_minimum_distance| 5| 10000| 30000|0.00668000| PASSED



rgb_permutations| 2| 100000| 3000|0.24834843| PASSED



rgb_permutations| 3| 100000| 3000|0.07901995| PASSED



rgb_permutations| 4| 100000| 3000|0.86363673| PASSED



rgb_permutations| 5| 100000| 3000|0.53472342| PASSED



rgb_lagged_sum| 0| 1000000| 3000|0.88718714| PASSED



rgb_lagged_sum| 1| 1000000| 3000|0.26184722| PASSED



rgb_lagged_sum| 2| 1000000| 3000|0.96379709| PASSED



rgb_lagged_sum| 3| 1000000| 3000|0.42731884| PASSED



rgb_lagged_sum| 4| 1000000| 3000|0.97153879| PASSED
rgb_lagged_sum| 5| 1000000| 3000|0.44772137| PASSED
rgb_lagged_sum| 6| 1000000| 3000|0.98129048| PASSED
rgb_lagged_sum| 7| 1000000| 3000|0.14721559| PASSED
rgb_lagged_sum| 8| 1000000| 3000|0.56080283| PASSED
rgb_lagged_sum| 9| 1000000| 3000|0.10075053| PASSED
rgb_lagged_sum| 10| 1000000| 3000|0.52807343| PASSED
rgb_lagged_sum| 11| 1000000| 3000|0.16251504| PASSED
rgb_lagged_sum| 12| 1000000| 3000|0.06012319| PASSED
rgb_lagged_sum| 13| 1000000| 3000|0.02819854| PASSED



rgb_lagged_sum| 14| 1000000| 3000|0.56292316| PASSED



rgb_lagged_sum| 15| 1000000| 3000|0.03627918| PASSED



rgb_lagged_sum| 16| 1000000| 3000|0.31141215| PASSED



rgb_lagged_sum| 17| 1000000| 3000|0.23430245| PASSED



rgb_lagged_sum| 18| 1000000| 3000|0.96322096| PASSED



rgb_lagged_sum| 19| 1000000| 3000|0.05275294| PASSED



rgb_lagged_sum| 20| 1000000| 3000|0.16858733| PASSED



rgb_lagged_sum| 21| 1000000| 3000|0.27858252| PASSED



rgb_lagged_sum| 22| 1000000| 3000|0.86056685| PASSED



rgb_lagged_sum| 23| 1000000| 3000|0.49540101| PASSED



rgb_lagged_sum| 24| 1000000| 3000|0.96278283| PASSED



rgb_lagged_sum| 25| 1000000| 3000|0.85687248| PASSED
rgb_lagged_sum| 26| 1000000| 3000|0.52521927| PASSED
rgb_lagged_sum| 27| 1000000| 3000|0.47528244| PASSED
rgb_lagged_sum| 28| 1000000| 3000|0.68680905| PASSED
rgb_lagged_sum| 29| 1000000| 3000|0.95196801| PASSED
rgb_lagged_sum| 30| 1000000| 3000|0.35409145| PASSED
rgb_lagged_sum| 31| 1000000| 3000|0.79745235| PASSED
rgb_lagged_sum| 32| 1000000| 3000|0.93842994| PASSED
rgb_kstest_test| 0| 10000| 30000|0.00167822| WEAK
dab_bytedistrib| 0| 51200000| 30|0.80854497| PASSED
dab_dct| 256| 50000| 30|0.86426890| PASSED
Preparing to run test 207. ntuple = 0
dab_filltree| 32| 15000000| 30|0.66975905| PASSED
dab_filltree| 32| 15000000| 30|0.56236231| PASSED
Preparing to run test 208. ntuple = 0
dab_filltree2| 0| 5000000| 30|0.59454036| PASSED
dab_filltree2| 1| 5000000| 30|0.75484914| PASSED
Preparing to run test 209. ntuple = 0
dab_monobit2| 12| 65000000| 30|0.23905375| PASSED

real 1437m24.217s
user 1948m33.944s
sys 88m11.892s