| // Use smaller statistics when running on simulators, so it takes less time. |
| // { dg-options "-DSAMPLES=30000" { target simulator } } |
| // { dg-do run { target c++11 } } |
| |
| // Copyright (C) 2010-2023 Free Software Foundation, Inc. |
| // |
| // This file is part of the GNU ISO C++ Library. This library is free |
| // software; you can redistribute it and/or modify it under the |
| // terms of the GNU General Public License as published by the |
| // Free Software Foundation; either version 3, or (at your option) |
| // any later version. |
| // |
| // This library is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU General Public License for more details. |
| // |
| // You should have received a copy of the GNU General Public License |
| // along with this library; see the file COPYING3. If not see |
| // <http://www.gnu.org/licenses/>. |
| |
| #include "chi2_quality.h" |
| |
| // Tests chi^2 for a distribution of strings that differ from each |
| // other by only a few bits. We start with an arbitrary base string, and |
| // flip three random bits for each member of the set. |
| void |
| test_bit_flip_set() |
| { |
| const unsigned long N = SAMPLES; |
| const unsigned long k = N/100; |
| const unsigned int len = 67; |
| const unsigned int bitlen = len * 8; |
| const unsigned int bits_to_flip = 3; |
| const char base[len+1] = "abcdefghijklmnopqrstuvwxyz" |
| "ABCDEFGHIJKLMNOPQRSTUVWXYZ" |
| "0123456789!@#$%"; |
| |
| std::unordered_set<std::string> set; |
| while (set.size() < N) |
| { |
| std::string s(base, base+len); |
| for (unsigned int i = 0; i < bits_to_flip; ++i) |
| { |
| int bit = rand() % bitlen; |
| s[bit/8] ^= (1 << (bit%8)); |
| } |
| set.insert(s); |
| } |
| |
| double chi2 = chi2_hash(set, k); |
| VERIFY( chi2 < k*1.1 ); |
| } |
| |
| int |
| main() |
| { |
| test_bit_flip_set(); |
| return 0; |
| } |