Philox32 Struct Reference

Classes
struct	array2x32
struct	array1x32

Public Types
typedef unsigned	result_type

Public Member Functions
	Philox32 (const uint64_t s)
	Philox32 (const unsigned hi, const unsigned lo=0x40ba6a95)
void	seed (const unsigned hi, const unsigned lo=0x40ba6a95)
void	seed64 (const uint64_t s)
Philox32 &	index (const uint64_t i)
unsigned	sample ()
unsigned	sample_range (const unsigned range)
unsigned	operator() ()

Static Public Member Functions
static constexpr unsigned	min ()
static constexpr unsigned	max ()

Protected Member Functions
array1x32	bumpkey (array1x32 key)
unsigned	mulhilo32 (unsigned a, unsigned b, unsigned *hip)
array2x32	round (array2x32 ctr, array1x32 key)
template<int R>
array2x32	philox2x32 (array2x32 ctr, array1x32 key)

Protected Attributes
uint64_t	n
array1x32	key

Detailed Description

Definition at line 114 of file rand123.h.

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Class Documentation

Philox32::array2x32

struct Philox32::array2x32

Definition at line 162 of file rand123.h.

Class Members
unsigned	v[2]

Philox32::array1x32

struct Philox32::array1x32

Definition at line 163 of file rand123.h.

Class Members
unsigned	v[1]

Member Typedef Documentation

result_type

typedef unsigned Philox32::result_type

Definition at line 159 of file rand123.h.

Constructor & Destructor Documentation

Philox32() [1/3]

Philox32::Philox32 ( )

inline

Definition at line 116 of file rand123.h.

: n(), key()  { seed64(0xcf492074862957a3); }

Philox32() [2/3]

Philox32::Philox32 ( const uint64_t s )

inline

Definition at line 117 of file rand123.h.

: n(), key() { seed(s); }

Philox32() [3/3]

Philox32::Philox32 ( const unsigned hi, const unsigned lo = 0x40ba6a95 )

inline

Definition at line 118 of file rand123.h.

: n(), key() { seed(hi, lo); }

Member Function Documentation

seed()

void Philox32::seed ( const unsigned hi, const unsigned lo = 0x40ba6a95 )

inline

Definition at line 120 of file rand123.h.

{ seed64(uint64_t(hi) << 32 | uint64_t(lo)); }

seed64()

void Philox32::seed64 ( const uint64_t s )

inline

Definition at line 121 of file rand123.h.

    { 
        n= 0;
        key= { { unsigned(s >> 32) } }; 
    }

index()

Philox32 & Philox32::index ( const uint64_t i )

inline

Definition at line 127 of file rand123.h.

    { 
        n= i;
        return *this;
    }

sample()

unsigned Philox32::sample ( )

inline

Definition at line 133 of file rand123.h.

    { 
        n++;
        array2x32 ctr= { { unsigned(n >>32), unsigned(n) } }; 
        return philox2x32<6>(ctr, key).v[0];        // 6 rounds
        //~ return philox2x32<10>(ctr, key).v[0];   // 10 rounds
    }

sample_range()

unsigned Philox32::sample_range ( const unsigned range )

inline

Definition at line 141 of file rand123.h.

    {
        // Efficiently Generating a Number in a Range
        // cf http://www.pcg-random.org/posts/bounded-rands.html
        unsigned divisor= ((-range) / range) + 1; // (2^32) / range
        if(divisor == 0) return 0;
        
        while(true)
        {
            unsigned x= sample() / divisor;
            if(x < range) return x;
        }
    }

operator()()

unsigned Philox32::operator() ( )

inline

Definition at line 156 of file rand123.h.

{ return sample(); }

min()

constexpr unsigned Philox32::min ( )

inlinestaticconstexpr

Definition at line 157 of file rand123.h.

{ return 0; }

max()

constexpr unsigned Philox32::max ( )

inlinestaticconstexpr

Definition at line 158 of file rand123.h.

{ return ~unsigned(0); }

bumpkey()

array1x32 Philox32::bumpkey ( array1x32 key )

inlineprotected

Definition at line 165 of file rand123.h.

    { 
        key.v[0] += 0x9E3779B9; 
        return key; 
    }

mulhilo32()

unsigned Philox32::mulhilo32 ( unsigned a, unsigned b, unsigned * hip )

inlineprotected

Definition at line 171 of file rand123.h.

    {
        uint64_t product = uint64_t(a) * uint64_t(b); 
        *hip= unsigned(product >> 32); 
        return unsigned(product); 
    }

round()

array2x32 Philox32::round ( array2x32 ctr, array1x32 key )

inlineprotected

Definition at line 178 of file rand123.h.

    { 
        uint32_t hi, lo= mulhilo32(0xd256d193, ctr.v[0], &hi); 
        
        return { { hi^key.v[0]^ctr.v[1], lo } }; 
    }    

philox2x32()

template<int R>

array2x32 Philox32::philox2x32 ( array2x32 ctr, array1x32 key )

inlineprotected

Definition at line 186 of file rand123.h.

    { 
        if(R>0) { ctr = round(ctr, key); } 
        if(R>1) { key = bumpkey(key); ctr = round(ctr, key); } 
        if(R>2) { key = bumpkey(key); ctr = round(ctr, key); } 
        if(R>3) { key = bumpkey(key); ctr = round(ctr, key); } 
        if(R>4) { key = bumpkey(key); ctr = round(ctr, key); } 
        if(R>5) { key = bumpkey(key); ctr = round(ctr, key); } 
        if(R>6) { key = bumpkey(key); ctr = round(ctr, key); } 
        if(R>7) { key = bumpkey(key); ctr = round(ctr, key); } 
        if(R>8) { key = bumpkey(key); ctr = round(ctr, key); } 
        if(R>9) { key = bumpkey(key); ctr = round(ctr, key); } 
        if(R>10) { key = bumpkey(key); ctr = round(ctr, key); } 
        if(R>11) { key = bumpkey(key); ctr = round(ctr, key); } 
        if(R>12) { key = bumpkey(key); ctr = round(ctr, key); } 
        if(R>13) { key = bumpkey(key); ctr = round(ctr, key); } 
        if(R>14) { key = bumpkey(key); ctr = round(ctr, key); } 
        if(R>15) { key = bumpkey(key); ctr = round(ctr, key); } 
        
        return ctr; 
    }

Member Data Documentation

n

uint64_t Philox32::n

protected

Definition at line 208 of file rand123.h.

key

array1x32 Philox32::key

protected

Definition at line 209 of file rand123.h.

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

• src/gKit/rand123.h