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-rw-r--r--src/vppinfra/test_random.c60
1 files changed, 60 insertions, 0 deletions
diff --git a/src/vppinfra/test_random.c b/src/vppinfra/test_random.c
index 49759eacb97..64513d56b57 100644
--- a/src/vppinfra/test_random.c
+++ b/src/vppinfra/test_random.c
@@ -38,6 +38,42 @@
#include <vppinfra/format.h>
#include <vppinfra/bitmap.h>
+static u32 outcome_frequencies[] = {
+ 8, 5, 9, 2, 7, 5,
+};
+
+
+int
+test_chisquare (void)
+{
+ u64 *values = 0;
+ int i;
+ f64 d, delta_d;
+
+ vec_validate (values, 5);
+
+ for (i = 0; i < 6; i++)
+ values[i] = (u64) outcome_frequencies[i];
+
+ d = clib_chisquare (values);
+
+ delta_d = d - 5.333;
+
+ if (delta_d < 0.0)
+ delta_d = -delta_d;
+
+ if (delta_d < 0.001)
+ {
+ fformat (stdout, "chisquare OK...\n");
+ return 0;
+ }
+ else
+ {
+ fformat (stdout, "chisquare BAD, d = %.3f\n", d);
+ return -1;
+ }
+}
+
static u32 known_random_sequence[] = {
0x00000000, 0x3c6ef35f, 0x47502932, 0xd1ccf6e9,
0xaaf95334, 0x6252e503, 0x9f2ec686, 0x57fe6c2d,
@@ -54,6 +90,8 @@ test_random_main (unformat_input_t * input)
uword print;
u32 seed;
u32 *seedp = &seed;
+ u64 *counts = 0;
+ f64 d;
/* first, check known sequence from Numerical Recipes in C, 2nd ed.
page 284 */
@@ -118,6 +156,28 @@ test_random_main (unformat_input_t * input)
continue;
}
+ if (test_chisquare ())
+ return (-1);
+
+ /* Simple randomness tests based on X2 stats */
+ vec_validate (counts, 255);
+
+ for (i = 0; i < 1000000; i++)
+ {
+ u32 random_index;
+ u32 r = random_u32 (&seed);
+
+ random_index = r & 0xFF;
+
+ counts[random_index]++;
+ }
+
+ d = clib_chisquare (counts);
+
+ fformat (stdout, "%d random octets, chisquare stat d = %.3f\n", i, d);
+
+ vec_free (counts);
+
return 0;
}