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ca9431f7 | 1 | // Use smaller statistics when running on simulators, so it takes less time. |
18a20f3f JW |
2 | // { dg-options "-DSAMPLES=30000" { target simulator } } |
3 | // { dg-do run { target c++11 } } | |
ca9431f7 | 4 | |
a5544970 | 5 | // Copyright (C) 2010-2019 Free Software Foundation, Inc. |
ca9431f7 HPN |
6 | // |
7 | // This file is part of the GNU ISO C++ Library. This library is free | |
8 | // software; you can redistribute it and/or modify it under the | |
9 | // terms of the GNU General Public License as published by the | |
10 | // Free Software Foundation; either version 3, or (at your option) | |
11 | // any later version. | |
12 | // | |
13 | // This library is distributed in the hope that it will be useful, | |
14 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | // GNU General Public License for more details. | |
17 | // | |
18 | // You should have received a copy of the GNU General Public License | |
19 | // along with this library; see the file COPYING3. If not see | |
20 | // <http://www.gnu.org/licenses/>. | |
21 | ||
22 | #include "chi2_quality.h" | |
23 | ||
24 | // Tests chi^2 for a distribution of strings that differ from each | |
25 | // other by only a few bits. We start with an arbitrary base string, and | |
26 | // flip three random bits for each member of the set. | |
27 | void | |
28 | test_bit_flip_set() | |
29 | { | |
ca9431f7 HPN |
30 | const unsigned long N = SAMPLES; |
31 | const unsigned long k = N/100; | |
32 | const unsigned int len = 67; | |
33 | const unsigned int bitlen = len * 8; | |
34 | const unsigned int bits_to_flip = 3; | |
35 | const char base[len+1] = "abcdefghijklmnopqrstuvwxyz" | |
36 | "ABCDEFGHIJKLMNOPQRSTUVWXYZ" | |
37 | "0123456789!@#$%"; | |
38 | ||
39 | std::unordered_set<std::string> set; | |
40 | while (set.size() < N) | |
41 | { | |
42 | std::string s(base, base+len); | |
43 | for (unsigned int i = 0; i < bits_to_flip; ++i) | |
44 | { | |
45 | int bit = rand() % bitlen; | |
46 | s[bit/8] ^= (1 << (bit%8)); | |
47 | } | |
48 | set.insert(s); | |
49 | } | |
50 | ||
51 | double chi2 = chi2_hash(set, k); | |
52 | VERIFY( chi2 < k*1.1 ); | |
53 | } | |
54 | ||
55 | int | |
56 | main() | |
57 | { | |
58 | test_bit_flip_set(); | |
59 | return 0; | |
60 | } |