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/* date = December 21st 2025 1:11 pm */
#ifndef EDITOR_RANDOM_H
#define EDITOR_RANDOM_H
//~ Random
#include <math.h>
#define PCG_MULTIPLIER_64 6364136223846793005ULL
#define PCG_INCREMENT_64 1442695040888963407ULL
typedef struct random_series random_series;
struct random_series
{
u64 State;
};
internal void
RandomStep(random_series *Series)
{
u64 NewState = (Series->State) * PCG_MULTIPLIER_64 + PCG_INCREMENT_64;
Series->State = NewState;
}
internal void
RandomSeed(random_series *Series, u64 Seed)
{
Series->State = 0;
RandomStep(Series);
Series->State += Seed;
RandomStep(Series);
}
internal void
RandomLeap(random_series *Series, u64 Delta)
{
u64 Increment = PCG_INCREMENT_64;
u64 Multiplier = PCG_MULTIPLIER_64;
u64 AccumulatedMult = 1u;
u64 AccumulatedInc = 0u;
while(Delta > 0)
{
if(Delta & 1)
{
AccumulatedMult *= Multiplier;
AccumulatedInc = AccumulatedInc * Multiplier + Increment;
}
Increment = (Multiplier + 1) * Increment;
Multiplier *= Multiplier;
Delta /= 2;
}
u64 NewState = AccumulatedMult * Series->State + AccumulatedInc;
Series->State = NewState;
}
internal u32
RandomNext(random_series *Series)
{
u32 Result = 0;
Result = (u32)((Series->State ^ (Series->State >> 22)) >> (22 + (Series->State >> 61)));
RandomStep(Series);
return Result;
}
internal f32
RandomF32(random_series *Series)
{
f32 Result = ldexpf((f32)RandomNext(Series), -32);
return Result;
}
internal f32
RandomUnilateral(random_series *Series)
{
f32 Result = RandomF32(Series);
return Result;
}
internal f32
RandomBilateral(random_series *Series)
{
f32 Result = 2.0f*RandomUnilateral(Series) - 1.0f;
return Result;
}
internal f32
RandomBetween(random_series *Series, f32 Min, f32 Max)
{
f32 Range = Max - Min;
f32 Result = Min + RandomUnilateral(Series)*Range;
return Result;
}
#endif //EDITOR_RANDOM_H
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