65 lines
2.0 KiB
C++
65 lines
2.0 KiB
C++
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#include "rand/xorshift.hpp"
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#include "rand/lcg.hpp"
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#include "tap.hpp"
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#include "maths.hpp"
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#include "types/string.hpp"
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///////////////////////////////////////////////////////////////////////////////
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template <>
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std::string
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type_to_string<util::rand::xorshift<uint32_t>> (void) { return "xorshift<uint32_t>"; }
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template <>
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std::string
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type_to_string<util::rand::xorshift<uint64_t>> (void) { return "xorshift<uint64_t>"; }
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template <>
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std::string
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type_to_string<util::rand::lcg_t> (void) { return "lcg_t"; }
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///////////////////////////////////////////////////////////////////////////////
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/// check random outputs are roughly divisible between a number of fixed width
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/// buckets.
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///
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/// this is not anything close to a strict statistical test. it is more aimed
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/// at link testing and basic functionality verification within a small
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/// resource footprint (ie, fast unit testing).
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template <typename G, typename ...Args>
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void
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test_buckets (util::TAP::logger &tap, Args&& ...args)
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{
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constexpr unsigned BUCKET_BITS = 8u;
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constexpr size_t BUCKET_COUNT = 1u << BUCKET_BITS;
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constexpr unsigned BUCKET_MASK = BUCKET_COUNT - 1u;
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constexpr unsigned EXPECTED = 1024u;
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constexpr unsigned ITERATIONS = BUCKET_COUNT * EXPECTED;
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unsigned buckets[BUCKET_COUNT] = {};
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G gen (std::forward<Args> (args)...);
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for (unsigned i = 0; i < ITERATIONS; ++i)
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++buckets[gen () & BUCKET_MASK];
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tap.expect (std::find_if (std::cbegin (buckets),
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std::cend (buckets),
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[] (auto v) { return v < EXPECTED * 3 / 4; }) == std::cend (buckets),
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"bucket counts for %s", type_to_string<G> ());
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}
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///////////////////////////////////////////////////////////////////////////////
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int
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main (int,char**)
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{
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util::TAP::logger tap;
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test_buckets<util::rand::xorshift<uint32_t>> (tap, 0x1234u);
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test_buckets<util::rand::xorshift<uint64_t>> (tap, 0x1234u);
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test_buckets<util::rand::lcg_t> (tap, 0x1234u);
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return tap.status ();
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}
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