rand: add 64-bit tausworthe variant with a 2^258 cycle

[fio.git] / lib / gauss.c

diff --git a/lib/gauss.c b/lib/gauss.c
index cd8b6e3e491a8669b3d5cad6e92c80567d656acb..afd0490d54786130acf04e0bb3c64bd8a4473bbd 100644 (file)
--- a/lib/gauss.c
+++ b/lib/gauss.c
@@ -15,7 +15,7 @@ static int gauss_dev(struct gauss_state *gs)
                return 0;
 
        r = __rand(&gs->r);
                return 0;
 
        r = __rand(&gs->r);

-       vr = gs->stddev * (r / (FRAND_MAX + 1.0));
+       vr = gs->stddev * (r / (FRAND32_MAX + 1.0));

 
        return vr - gs->stddev / 2;
 }
 
        return vr - gs->stddev / 2;
 }


@@ -41,13 +41,16 @@ unsigned long long gauss_next(struct gauss_state *gs)
        return __hash_u64(sum) % gs->nranges;
 }
 
        return __hash_u64(sum) % gs->nranges;
 }
 

-void gauss_init(struct gauss_state *gs, unsigned long nranges, unsigned int d,
+void gauss_init(struct gauss_state *gs, unsigned long nranges, double dev,

                unsigned int seed)
 {
        memset(gs, 0, sizeof(*gs));
                unsigned int seed)
 {
        memset(gs, 0, sizeof(*gs));

-       init_rand_seed(&gs->r, seed);
+       init_rand_seed(&gs->r, seed, 0);

        gs->nranges = nranges;
        gs->nranges = nranges;

-       gs->stddev = d;
-       if (gs->stddev > nranges / 2)
-               gs->stddev = nranges / 2;
+
+       if (dev != 0.0) {
+               gs->stddev = ceil((double) (nranges * 100.0) / dev);
+               if (gs->stddev > nranges / 2)
+                       gs->stddev = nranges / 2;
+       }

 }
 }