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Diffstat (limited to 'xorshift.c')
-rw-r--r-- | xorshift.c | 44 |
1 files changed, 0 insertions, 44 deletions
diff --git a/xorshift.c b/xorshift.c deleted file mode 100644 index 9291b90..0000000 --- a/xorshift.c +++ /dev/null @@ -1,44 +0,0 @@ -/* “An experimental exploration of Marsaglia’s xorshift generators, - * scrambled”, Sebastiano Vigna */ - -#include <sys/types.h> -#include <sys/stat.h> -#include <fcntl.h> -#include <assert.h> -#include <unistd.h> - -#include "xorshift.h" - -uint64_t xorshift_step (randctx * const st) { - uint64_t s0 = st->s[ st->p ]; - uint64_t s1 = st->s[ st->p = ( st->p + 1 ) & (XORSHIFT_S-1) ]; - s1 ^= s1 << 31; // a - s1 ^= s1 >> 11; // b - s0 ^= s0 >> 30; // c - return ( st->s[ st->p ] = s0 ^ s1 ) * 1181783497276652981LL; -} - -static uint64_t rand64 () { - unsigned long long rand; - while (!__builtin_ia32_rdrand64_step (&rand)); - return rand; -} - -void xorshift_seed (randctx * const st) { - /* seed with high-quality randomness */ - for (unsigned char i = 0; i < XORSHIFT_S; i++) { - st->s[i] = rand64 (); - } -} - -#if 0 -uint64_t xorshift_step (randctx * const st) { - uint64_t x = st->s[0]; - x ^= x >> 12; // a - x ^= x << 25; // b - x ^= x >> 27; // c - st->s[0] = x; - return x * 2685821657736338717LL; -} -#endif - |