56 lines
1.3 KiB
C++
56 lines
1.3 KiB
C++
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#include <assert.h>
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#include <stdio.h>
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#ifdef HAVE_INTTYPES_H
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#include <inttypes.h>
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#elif HAVE_STDINT_H
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#include <stdint.h>
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#else
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typedef int int32_t;
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typedef unsigned int uint32_t;
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typedef unsigned long long uint64_t;
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#endif
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#define static_assert(x) switch(x) case 0: case (x):
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class SRandom
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{
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static const uint64_t m = 2147483647;
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static const uint64_t a = 16807;
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static const uint32_t zero = 0x23456789;
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uint32_t last;
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public:
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static const int32_t Maximum = 0x7fffffff;
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public:
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inline SRandom() : last (zero) {}
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inline void reset() { last = zero; }
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inline uint32_t next()
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{
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static_assert(sizeof(uint64_t) == 8);
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static_assert(sizeof(uint32_t) == 4);
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static_assert(sizeof(int32_t) == 4);
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uint64_t tmp = (a * last) % m;
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last = (uint32_t) tmp;
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return ((int)last) & Maximum;
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}
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inline static void check()
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{
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static const int test_iterations = 10000000;
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SRandom r;
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int32_t hash = 0;
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for (int i = 0; i < test_iterations; i++)
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{
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int32_t n = r.next();
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assert(n != 0);
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hash ^= n;
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}
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fprintf(stderr, "xor sum 1...%d = %u\n", test_iterations, hash);
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assert(hash == 1080076236);
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}
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};
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