Philox Struct Reference

Classes
struct	array2x64
struct	array1x64

Public Types
typedef unsigned	result_type

Public Member Functions
	Philox (const uint64_t s)
	Philox (const unsigned hi, const unsigned lo=0x40ba6a95)
void	seed (const unsigned hi, const unsigned lo=0x40ba6a95)
void	seed64 (const uint64_t s)
Philox &	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
array1x64	bumpkey (array1x64 key)
uint64_t	mulhilo64 (uint64_t a, uint64_t b, uint64_t *hip)
array2x64	round (array2x64 ctr, array1x64 key)
template<int R>
array2x64	philox2x64 (array2x64 ctr, array1x64 key)

Protected Attributes
array2x64	ctr
array1x64	key

Detailed Description

Definition at line 12 of file rand123.h.

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Class Documentation

Philox::array2x64

struct Philox::array2x64

Definition at line 60 of file rand123.h.

Class Members
uint64_t	v[2]

Philox::array1x64

struct Philox::array1x64

Definition at line 61 of file rand123.h.

Class Members
uint64_t	v[1]

Member Typedef Documentation

result_type

typedef unsigned Philox::result_type

Definition at line 57 of file rand123.h.

Constructor & Destructor Documentation

Philox() [1/3]

Philox::Philox ( )

inline

Definition at line 14 of file rand123.h.

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

Philox() [2/3]

Philox::Philox ( const uint64_t s )

inline

Definition at line 15 of file rand123.h.

: ctr(), key() { seed64(s); }

Philox() [3/3]

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

inline

Definition at line 17 of file rand123.h.

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

Member Function Documentation

seed()

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

inline

Definition at line 18 of file rand123.h.

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

seed64()

void Philox::seed64 ( const uint64_t s )

inline

Definition at line 20 of file rand123.h.

    { 
        ctr= { { 0, 0x838ca1328d07d3ba } }; 
        key= { { s } }; 
    }

index()

Philox & Philox::index ( const uint64_t i )

inline

Definition at line 26 of file rand123.h.

    { 
        ctr= { { i, 0x838ca1328d07d3ba } }; 
        return *this;
    }

sample()

unsigned Philox::sample ( )

inline

Definition at line 32 of file rand123.h.

    { 
        ctr.v[0]++;
        return philox2x64<6>(ctr, key).v[0];        // 6 rounds
        //~ return philox2x64<10>(ctr, key).v[0];   // 10 rounds
    }

sample_range()

unsigned Philox::sample_range ( const unsigned range )

inline

Definition at line 39 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 Philox::operator() ( )

inline

Definition at line 54 of file rand123.h.

{ return sample(); }

min()

constexpr unsigned Philox::min ( )

inlinestaticconstexpr

Definition at line 55 of file rand123.h.

{ return 0; }

max()

constexpr unsigned Philox::max ( )

inlinestaticconstexpr

Definition at line 56 of file rand123.h.

{ return ~unsigned(0); }

bumpkey()

array1x64 Philox::bumpkey ( array1x64 key )

inlineprotected

Definition at line 63 of file rand123.h.

    { 
        key.v[0] += 0x9E3779B97F4A7C15UL; 
        return key; 
    }

mulhilo64()

uint64_t Philox::mulhilo64 ( uint64_t a, uint64_t b, uint64_t * hip )

inlineprotected

Definition at line 69 of file rand123.h.

    { 
        __uint128_t product = __uint128_t(a) * __uint128_t(b); 
        *hip= uint64_t(product >> 64); 
        return uint64_t(product); 
    }

round()

array2x64 Philox::round ( array2x64 ctr, array1x64 key )

inlineprotected

Definition at line 76 of file rand123.h.

    { 
        uint64_t hi; 
        uint64_t lo = mulhilo64(0xD2B74407B1CE6E93UL, ctr.v[0], &hi); 
        
        return { { hi^key.v[0]^ctr.v[1], lo } }; 
    }

philox2x64()

template<int R>

array2x64 Philox::philox2x64 ( array2x64 ctr, array1x64 key )

inlineprotected

Definition at line 85 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

ctr

array2x64 Philox::ctr

protected

Definition at line 107 of file rand123.h.

key

array1x64 Philox::key

protected

Definition at line 108 of file rand123.h.

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

• src/gKit/rand123.h