Created
January 21, 2024 23:06
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PRNG with seeding and output - see link in code
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| // https://www.reddit.com/r/RNG/comments/19a2q24/collatzweyl_generators/?utm_source=share&utm_medium=web2x&context=3 | |
| // $ gcc -Wall -O3 Collatz-Weyl.c -o Collatz-Weyl | |
| // $ ./Collatz-Weyl | pv > /dev/null <-- 650MiB/s on 2018 Zeon VM | |
| // compared with 400MiB/s for ChaCha20 | |
| #include <stdio.h> | |
| #include <assert.h> | |
| static __uint128_t c[4] = {0, 0, 0, 0}; // c[0] must be odd | |
| __uint128_t CWG128(void) { | |
| c[1] = (c[1] >> 1) * ((c[2] += c[1]) | 1) ^ (c[3] += c[0]); | |
| return c[2] >> 96 ^ c[1]; | |
| } | |
| int main(void) { | |
| FILE * fr = fopen("/dev/random", "r"); | |
| assert(fr); | |
| assert(1 == fread(&c[0], sizeof(c[0]), 1, fr)); | |
| fclose(fr); | |
| c[0] |= 1U; // odd | |
| for(int i=0; i<96; i++) CWG128(); | |
| while(1) { | |
| __uint128_t o = CWG128(); | |
| fwrite(&o, sizeof(o), 1, stdout); | |
| } | |
| return(0); | |
| } |
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