108 lines
2.7 KiB
C++
108 lines
2.7 KiB
C++
#pragma once
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#include "basis/seadRawPrint.h"
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#include "basis/seadTypes.h"
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#include "prim/seadBitUtil.h"
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namespace sead
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{
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/// A fast non-cryptographically secure pseudorandom number generator based on Xorshift128.
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class Random
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{
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public:
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Random() { init(); }
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Random(u32 seed) { init(seed); }
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/// @warning Parameters have to be chosen carefully to get a long period. Using this is not
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/// recommended.
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Random(u32 seed_x, u32 seed_y, u32 seed_z, u32 seed_w) { init(seed_x, seed_y, seed_z, seed_w); }
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/// Reset and seed the engine with the current system tick count.
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void init();
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/// Reset and seed the engine with the specified value.
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void init(u32 seed);
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/// @warning Parameters have to be chosen carefully to get a long period. Using this is not
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/// recommended.
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void init(u32 seed_x, u32 seed_y, u32 seed_z, u32 seed_w);
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/// Generate a random u32.
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u32 getU32();
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/// Generate a random u64.
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u64 getU64();
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/// Generate a random u32 in [0 .. max).
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u32 getU32(u32 max);
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/// Generate a random s32 in [a .. b).
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/// Note that this does not provide a uniform distribution.
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s32 getS32Range(s32 a, s32 b);
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/// Generate a random s64 in [a .. b).
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/// Note that this does not provide a uniform distribution.
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s64 getS64Range(s64 a, s64 b);
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/// Generate a random f32 in [0, 1).
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f32 getF32();
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/// Generate a random f32 in [a, b).
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f32 getF32Range(f32 a, f32 b);
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/// Generate a random f64 in [0, 1).
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f64 getF64();
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/// Generate a random f64 in [a, b).
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f64 getF64Range(f64 a, f64 b);
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/// Generate a random boolean.
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bool getBool();
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void getContext(u32* x, u32* y, u32* z, u32* w) const;
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private:
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u32 mX;
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u32 mY;
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u32 mZ;
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u32 mW;
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};
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inline u32 Random::getU32(u32 max)
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{
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return getU32() * u64(max) >> 32u;
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}
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inline s32 Random::getS32Range(s32 a, s32 b)
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{
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SEAD_ASSERT_MSG(a <= b, "b[%d] >= a[%d]", a, b);
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return getU32(b - a) + static_cast<u32>(a);
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}
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// UNCHECKED
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inline s64 Random::getS64Range(s64 a, s64 b)
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{
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SEAD_ASSERT_MSG(a <= b, "b[%ld] >= a[%ld]", a, b);
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return (getU32() * u64(b - a) >> 32u) + a;
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}
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inline f32 Random::getF32()
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{
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return BitUtil::bitCast<f32>((getU32() >> 9u) | 0x3F800000u) - 1.0f;
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}
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inline f32 Random::getF32Range(f32 a, f32 b)
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{
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SEAD_ASSERT_MSG(a <= b, "b[%f] >= a[%f]", a, b);
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return a + (b - a) * getF32();
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}
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// UNCHECKED
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inline f64 Random::getF64()
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{
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return BitUtil::bitCast<f64>((getU64() >> 12u) | 0x3FF0'0000'0000'0000lu) - 1.0;
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}
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// UNCHECKED
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inline f64 Random::getF64Range(f64 a, f64 b)
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{
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SEAD_ASSERT_MSG(a <= b, "b[%f] >= a[%f]", a, b);
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return a + (b - a) * getF64();
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}
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// UNCHECKED
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inline bool Random::getBool()
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{
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return getU32() & 0x80000000u;
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}
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} // namespace sead
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