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68 lines
1.1 KiB
68 lines
1.1 KiB
5 years ago
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#include "engine/random.hpp"
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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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/**
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* Specifies the increment used in the Borland C/C++ pseudo-random.
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*/
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const uint32_t RndInc = 1;
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/**
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* Specifies the multiplier used in the Borland C/C++ pseudo-random number generator algorithm.
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*/
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const uint32_t RndMult = 0x015A4E35;
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/**
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* @brief Set the RNG seed
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* @param s RNG seed
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*/
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void SetRndSeed(uint32_t s)
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{
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sglGameSeed = s;
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}
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/**
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* @brief Advance the internal RNG seed and return the new value
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* @return RNG seed
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*/
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int32_t AdvanceRndSeed()
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{
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sglGameSeed = (RndMult * sglGameSeed) + RndInc;
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return GetRndSeed();
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}
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/**
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* @brief Get the current RNG seed
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* @return RNG seed
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*/
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int32_t GetRndSeed()
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{
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return abs(static_cast<int32_t>(sglGameSeed));
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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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/**
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* @brief Main RNG function
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* @param v The upper limit for the return value
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* @return A random number from 0 to (v-1)
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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 < 0xFFFF)
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return (AdvanceRndSeed() >> 16) % v;
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return AdvanceRndSeed() % v;
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}
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}
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