distibutions: Extend flexibility of non-uniform random distributions

[fio.git] / lib / gauss.c

diff --git a/lib/gauss.c b/lib/gauss.c
index 3f84dbc6d04c802831c6ae5e9585b4736144b04c..c64f61e7c4dea85ce6ee8d65005807edec74db8c 100644 (file)
--- a/lib/gauss.c
+++ b/lib/gauss.c
@@ -40,11 +40,11 @@ unsigned long long gauss_next(struct gauss_state *gs)
        if (!gs->disable_hash)
                sum = __hash_u64(sum);
 
-       return sum % gs->nranges;
+       return (sum + gs->rand_off) % gs->nranges;
 }
 
 void gauss_init(struct gauss_state *gs, unsigned long nranges, double dev,
-               unsigned int seed)
+               double center, unsigned int seed)
 {
        memset(gs, 0, sizeof(*gs));
        init_rand_seed(&gs->r, seed, 0);
@@ -55,6 +55,10 @@ void gauss_init(struct gauss_state *gs, unsigned long nranges, double dev,
                if (gs->stddev > nranges / 2)
                        gs->stddev = nranges / 2;
        }
+       if (center == -1)
+         gs->rand_off = 0;
+       else
+         gs->rand_off = nranges * (center - 0.5);
 }
 
 void gauss_disable_hash(struct gauss_state *gs)