tests/test-random.c

   1 /*
   2  * Copyright (c) 2008, 2009, 2010, 2014 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18 #undef NDEBUG
  19 #include "random.h"
  20 #include <stdio.h>
  21 #include <string.h>
  22 #include "ovstest.h"
  23
  24 static void
  25 test_random_main(int argc OVS_UNUSED, char *argv[] OVS_UNUSED)
  26 {
  27     enum { N_ROUNDS = 10000 };
  28     unsigned long long int total;
  29     int hist16[8][16];
  30     int hist2[32];
  31     int i;
  32
  33     random_set_seed(1);
  34
  35     total = 0;
  36     memset(hist2, 0, sizeof hist2);
  37     memset(hist16, 0, sizeof hist16);
  38     for (i = 0; i < N_ROUNDS; i++) {
  39         uint32_t x;
  40         int j;
  41
  42         x = random_uint32();
  43
  44         total += x;
  45
  46         for (j = 0; j < 32; j++) {
  47             if (x & (1u << j)) {
  48                 hist2[j]++;
  49             }
  50         }
  51
  52         for (j = 0; j < 8; j++) {
  53             hist16[j][(x >> (j * 4)) & 15]++;
  54         }
  55     }
  56
  57     printf("average=%08llx\n", total / N_ROUNDS);
  58
  59     printf("\nbit      0     1\n");
  60     for (i = 0; i < 32; i++) {
  61         printf("%3d %5d %5d\n", i, N_ROUNDS - hist2[i], hist2[i]);
  62     }
  63     printf("(expected values are %d)\n", N_ROUNDS / 2);
  64
  65     printf("\nnibble   0   1   2   3   4   5   6   7   8   9  10  11  12  "
  66            "13  14  15\n");
  67     for (i = 0; i < 8; i++) {
  68         int j;
  69
  70         printf("%6d", i);
  71         for (j = 0; j < 16; j++) {
  72             printf(" %3d", hist16[i][j]);
  73         }
  74         printf("\n");
  75     }
  76     printf("(expected values are %d)\n", N_ROUNDS / 16);
  77 }
  78
  79 OVSTEST_REGISTER("test-random", test_random_main);