mtcore::Prng Struct Reference

Represents a Pseudo Random Number Generator. More...

#include <random.hpp>

Collaboration diagram for mtcore::Prng:

Public Member Functions
bool	can_get1_0 () const noexcept
bool	can_get_uint () const noexcept
bool	can_reseed () const noexcept
double	next1_0 () noexcept
	Gets a number n such that $0 <= n < 1$ Will abort of canGet1_0 is false!
u64	next_uint () noexcept
	Gets the next unsigned 64-bit integer from the PRNG Will abort of canGetUInt is false!
u64	in_range (const u64 min, const u64 max) noexcept
	Gets number between min (inclusive) and max value (exclusive) Prioritizes nextUInt over next1_0.
f64	in_range_f64 (const f64 min, const f64 max) noexcept
	Gets number between min (inclusive) and max value (exclusive) Prioritizes next1_0 over nextUInt.
Result< void, SeedError >	seed (const u64 seed) noexcept
	Reseeds the PRNG.
void	deinit () noexcept
	Deinitializes a PRNG NOTE: It is NOT safe to use a PRNG after it has been deinitialized!

Public Attributes
PrngState	state
const PrngVTable *	vtable

Detailed Description

Represents a Pseudo Random Number Generator.

Definition at line 100 of file random.hpp.

Member Function Documentation

can_get1_0()

bool mtcore::Prng::can_get1_0 ( ) const

inlinenodiscardnoexcept

Returns

Returns true if can safely call next1_0

Definition at line 109 of file random.hpp.

{ return vtable && vtable->next1_0 != nullptr; }

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can_get_uint()

bool mtcore::Prng::can_get_uint ( ) const

inlinenodiscardnoexcept

Returns

Returns true if can safely call nextUInt

Definition at line 114 of file random.hpp.

{ return vtable && vtable->nextUint != nullptr; }

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can_reseed()

bool mtcore::Prng::can_reseed ( ) const

inlinenodiscardnoexcept

Returns

Returns true if can safely call seed

Definition at line 119 of file random.hpp.

{ return vtable && vtable->seed != nullptr; }

deinit()

void mtcore::Prng::deinit ( )

inlinenoexcept

Deinitializes a PRNG NOTE: It is NOT safe to use a PRNG after it has been deinitialized!

Definition at line 214 of file random.hpp.

                           {
      mtdefer { vtable = nullptr; };
      if (vtable && vtable->deinit) {
        vtable->deinit(state);
      }
    }

in_range()

u64 mtcore::Prng::in_range ( const u64 min, const u64 max )

inlinenodiscardnoexcept

Gets number between min (inclusive) and max value (exclusive) Prioritizes nextUInt over next1_0.

Parameters

min	Minimum value
max	Maximum value

Returns

number between value

Definition at line 148 of file random.hpp.

                                                                      {
      ensure(min < max, "INVALID RANGE PROVIDED");
      ensure(can_get_uint() || can_get1_0(), "INVALID PRNG - MUST HAVE next1_0 OR nextUint IN VTABLE");
 
      const u64 count = max - min;
 
      if (count == 1) {
        return min;
      }
 
      const auto offset = std::numeric_limits<u64>::max() % count;
      if (can_get_uint()) {
        u64 res;
        do {
          res = next_uint();
        } while (res >= (std::numeric_limits<u64>::max() - offset));
        res %= count;
        return res + min;
      }
      else {
        const long double v = next1_0();
        return static_cast<u64>(floor(v * static_cast<long double>(count))) + min;
      }
    }

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in_range_f64()

f64 mtcore::Prng::in_range_f64 ( const f64 min, const f64 max )

inlinenodiscardnoexcept

Gets number between min (inclusive) and max value (exclusive) Prioritizes next1_0 over nextUInt.

Parameters

min	Minimum value
max	Maximum value

Returns

number between value

Definition at line 180 of file random.hpp.

                                                                          {
      ensure(min < max, "INVALID RANGE PROVIDED");
      ensure(can_get_uint() || can_get1_0(), "INVALID PRNG - MUST HAVE next1_0 OR nextUint IN VTABLE");
 
      const auto count = max - min;
 
      if (count == 1) {
        return min;
      }
 
      if (can_get1_0()) {
        const double v = next1_0();
        return v * count + min;
      }
      else {
        constexpr auto m      = 10000000000;
        const auto n          = in_range(0, m);
        const long double rng = static_cast<long double>(n) / static_cast<long double>(m);
        return static_cast<f64>(rng * count) + min;
      }
    }

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next1_0()

double mtcore::Prng::next1_0 ( )

inlinenodiscardnoexcept

Gets a number n such that $0 <= n < 1$ Will abort of canGet1_0 is false!

Definition at line 125 of file random.hpp.

                                            {
      ensure(vtable, "MISSING VTABLE FOR PRNG");
      ensure(vtable->next1_0, "MISSING next1_0 IN PRNG VTABLE");
      return vtable->next1_0(state);
    }

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next_uint()

u64 mtcore::Prng::next_uint ( )

inlinenodiscardnoexcept

Gets the next unsigned 64-bit integer from the PRNG Will abort of canGetUInt is false!

Definition at line 135 of file random.hpp.

                                           {
      ensure(vtable, "MISSING VTABLE FOR PRNG");
      ensure(vtable->nextUint, "MISSING nextUint IN PRNG VTABLE");
      return vtable->nextUint(state);
    }

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seed()

Result< void, SeedError > mtcore::Prng::seed ( const u64 seed )

inlinenodiscardnoexcept

Reseeds the PRNG.

Definition at line 205 of file random.hpp.

                                                                        {
      ensure(vtable && vtable->seed, "INVALID VTABLE!");
      return vtable->seed(state, seed);
    }

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Member Data Documentation

state

PrngState mtcore::Prng::state

Definition at line 102 of file random.hpp.

vtable

const PrngVTable* mtcore::Prng::vtable

Definition at line 104 of file random.hpp.

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The documentation for this struct was generated from the following file:

• random.hpp