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63 lines
1.3 KiB
63 lines
1.3 KiB
#include "engine/random.hpp" |
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#include <limits> |
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#include <random> |
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#include "utils/stdcompat/abs.hpp" |
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namespace devilution { |
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/** Current game seed */ |
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uint32_t sglGameSeed; |
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/** Borland C/C++ psuedo-random number generator needed for vanilla compatibility */ |
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std::linear_congruential_engine<uint32_t, 0x015A4E35, 1, 0> diabloGenerator; |
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void SetRndSeed(uint32_t seed) |
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{ |
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diabloGenerator.seed(seed); |
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sglGameSeed = seed; |
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} |
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uint32_t GetLCGEngineState() |
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{ |
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return sglGameSeed; |
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} |
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void DiscardRandomValues(unsigned count) |
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{ |
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while (count != 0) { |
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GenerateSeed(); |
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count--; |
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} |
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} |
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uint32_t GenerateSeed() |
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{ |
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sglGameSeed = diabloGenerator(); |
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return sglGameSeed; |
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} |
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int32_t AdvanceRndSeed() |
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{ |
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const int32_t seed = static_cast<int32_t>(GenerateSeed()); |
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// since abs(INT_MIN) is undefined behavior, handle this value specially |
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return seed == std::numeric_limits<int32_t>::min() ? std::numeric_limits<int32_t>::min() : abs(seed); |
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} |
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int32_t GenerateRnd(int32_t v) |
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{ |
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if (v <= 0) |
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return 0; |
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if (v <= 0x7FFF) // use the high bits to correct for LCG bias |
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return (AdvanceRndSeed() >> 16) % v; |
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return AdvanceRndSeed() % v; |
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} |
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bool FlipCoin(unsigned frequency) |
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{ |
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// Casting here because GenerateRnd takes a signed argument when it should take and yield unsigned. |
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return GenerateRnd(static_cast<int32_t>(frequency)) == 0; |
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} |
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} // namespace devilution
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