source: libcfa/src/bits/random.hfa@ c2dfa56a

// 
// Cforall Version 1.0.0 Copyright (C) 2022 University of Waterloo
// 
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// random.hfa -- 
// 
// Author           : Peter A. Buhr
// Created On       : Fri Jan 14 07:18:11 2022
// Last Modified By : Peter A. Buhr
// Last Modified On : Mon Mar 20 10:01:40 2023
// Update Count     : 180
// 

#pragma once

#include <stdint.h>                                                                             // uintXX_t

#define GLUE2( x, y ) x##y
#define GLUE( x, y ) GLUE2( x, y )

// Set default PRNG for architecture size.
#ifdef __x86_64__                                                                               // 64-bit architecture
        // 64-bit generators
        //#define LEHMER64
        //#define XORSHIFT_12_25_27
        #define XOSHIRO256PP
        //#define KISS_64

        // 32-bit generators
        //#define XORSHIFT_6_21_7
        #define XOSHIRO128PP
#else                                                                                                   // 32-bit architecture
        // 64-bit generators
        //#define XORSHIFT_13_7_17
        #define XOSHIRO256PP

        // 32-bit generators
        //#define XORSHIFT_6_21_7
        #define XOSHIRO128PP
#endif // __x86_64__

// Define C/CFA PRNG name and random-state.

#ifdef XOSHIRO256PP
#define PRNG_NAME_64 xoshiro256pp
#define PRNG_STATE_64_T GLUE(PRNG_NAME_64,_t)
typedef struct { uint64_t s0, s1, s2, s3; } PRNG_STATE_64_T;
#endif // XOSHIRO256PP

#ifdef XOSHIRO128PP
#define PRNG_NAME_32 xoshiro128pp
#define PRNG_STATE_32_T GLUE(PRNG_NAME_32,_t)
typedef struct { uint32_t s0, s1, s2, s3; } PRNG_STATE_32_T;
#endif // XOSHIRO128PP

#ifdef LEHMER64
#define PRNG_NAME_64 lehmer64
#define PRNG_STATE_64_T __uint128_t
#endif // LEHMER64

#ifdef WYHASH64
#define PRNG_NAME_64 wyhash64
#define PRNG_STATE_64_T uint64_t
#endif // LEHMER64

#ifdef XORSHIFT_13_7_17
#define PRNG_NAME_64 xorshift_13_7_17
#define PRNG_STATE_64_T uint64_t
#endif // XORSHIFT_13_7_17

#ifdef XORSHIFT_6_21_7
#define PRNG_NAME_32 xorshift_6_21_7
#define PRNG_STATE_32_T uint32_t
#endif // XORSHIFT_6_21_7

#ifdef XORSHIFT_12_25_27
#define PRNG_NAME_64 xorshift_12_25_27
#define PRNG_STATE_64_T uint64_t
#endif // XORSHIFT_12_25_27

#ifdef KISS_64
#define PRNG_NAME_64 kiss_64
#define PRNG_STATE_64_T GLUE(PRNG_NAME_64,_t)
typedef struct { uint64_t z, w, jsr, jcong; } PRNG_STATE_64_T;
#endif // KISS_^64

#ifdef XORWOW
#define PRNG_NAME_32 xorwow
#define PRNG_STATE_32_T GLUE(PRNG_NAME_32,_t)
typedef struct { uint32_t a, b, c, d, counter; } PRNG_STATE_32_T;
#endif // XOSHIRO128PP

#define PRNG_SET_SEED_64 GLUE(PRNG_NAME_64,_set_seed)
#define PRNG_SET_SEED_32 GLUE(PRNG_NAME_32,_set_seed)


// Default PRNG used by runtime.
#ifdef __x86_64__                                                                               // 64-bit architecture
#define PRNG_NAME PRNG_NAME_64
#define PRNG_STATE_T PRNG_STATE_64_T
#else                                                                                                   // 32-bit architecture
#define PRNG_NAME PRNG_NAME_32
#define PRNG_STATE_T PRNG_STATE_32_T
#endif // __x86_64__

#define PRNG_SET_SEED GLUE(PRNG_NAME,_set_seed)


// ALL PRNG ALGORITHMS ARE OPTIMIZED SO THAT THE PRNG LOGIC CAN HAPPEN IN PARALLEL WITH THE USE OF THE RESULT.
// Specifically, the current random state is copied for returning, before computing the next value.  As a consequence,
// the set_seed routine primes the PRNG by calling it with the state so the seed is not return as the first random
// value.


#ifdef __cforall                                                                                // don't include in C code (invoke.h)

// https://prng.di.unimi.it/xoshiro256starstar.c
//
// This is xoshiro256++ 1.0, one of our all-purpose, rock-solid generators.  It has excellent (sub-ns) speed, a state
// (256 bits) that is large enough for any parallel application, and it passes all tests we are aware of.
//
// For generating just floating-point numbers, xoshiro256+ is even faster.
//
// The state must be seeded so that it is not everywhere zero. If you have a 64-bit seed, we suggest to seed a
// splitmix64 generator and use its output to fill s.

#ifndef XOSHIRO256PP
typedef struct { uint64_t s0, s1, s2, s3; } xoshiro256pp_t;
#endif // ! XOSHIRO256PP

static inline uint64_t xoshiro256pp( xoshiro256pp_t & rs ) with(rs) {
        inline uint64_t rotl( const uint64_t x, int k ) {
                return (x << k) | (x >> (64 - k));
        } // rotl

        const uint64_t result = rotl( s0 + s3, 23 ) + s0;
        const uint64_t t = s1 << 17;

        s2 ^= s0;
        s3 ^= s1;
        s1 ^= s2;
        s0 ^= s3;
        s2 ^= t;
        s3 = rotl( s3, 45 );
        return result;
} // xoshiro256pp

static inline void xoshiro256pp_set_seed( xoshiro256pp_t & state, uint64_t seed ) {
        state = (xoshiro256pp_t){ seed, seed, seed, seed };
        xoshiro256pp( state );                                                          // prime
} // xoshiro256pp_set_seed

// https://prng.di.unimi.it/xoshiro128plusplus.c
//
// This is xoshiro128++ 1.0, one of our 32-bit all-purpose, rock-solid generators. It has excellent speed, a state size
// (128 bits) that is large enough for mild parallelism, and it passes all tests we are aware of.
//
// For generating just single-precision (i.e., 32-bit) floating-point numbers, xoshiro128+ is even faster.
//
// The state must be seeded so that it is not everywhere zero.

#ifndef XOSHIRO128PP
typedef struct { uint32_t s0, s1, s2, s3; } xoshiro128pp_t;
#endif // ! XOSHIRO128PP

static inline uint32_t xoshiro128pp( xoshiro128pp_t & rs ) with(rs) {
        inline uint32_t rotl( const uint32_t x, int k ) {
                return (x << k) | (x >> (32 - k));
        } // rotl

        const uint32_t result = rotl( s0 + s3, 7 ) + s0;
        const uint32_t t = s1 << 9;

        s2 ^= s0;
        s3 ^= s1;
        s1 ^= s2;
        s0 ^= s3;
        s2 ^= t;
        s3 = rotl( s3, 11 );
        return result;
} // xoshiro128pp

static inline void xoshiro128pp_set_seed( xoshiro128pp_t & state, uint32_t seed ) {
        state = (xoshiro128pp_t){ seed, seed, seed, seed };
        xoshiro128pp( state );                                                          // prime
} // xoshiro128pp_set_seed

#ifdef __SIZEOF_INT128__
        //--------------------------------------------------
        static inline uint64_t lehmer64( __uint128_t & state ) {
                __uint128_t ret = state;
                state *= 0x_da94_2042_e4dd_58b5;
                return ret >> 64;
        } // lehmer64

        static inline void lehmer64_set_seed( __uint128_t & state, uint64_t seed ) {
                // The seed needs to be coprime with the 2^64 modulus to get the largest period, so no factors of 2 in the seed.
                state = seed;
                lehmer64( state );                                                              // prime
        } // lehmer64_set_seed

        //--------------------------------------------------
        static inline uint64_t wyhash64( uint64_t & state ) {
                uint64_t ret = state;
                state += 0x_60be_e2be_e120_fc15;
                __uint128_t tmp;
                tmp = (__uint128_t) ret * 0x_a3b1_9535_4a39_b70d;
                uint64_t m1 = (tmp >> 64) ^ tmp;
                tmp = (__uint128_t)m1 * 0x_1b03_7387_12fa_d5c9;
                uint64_t m2 = (tmp >> 64) ^ tmp;
                return m2;
        } // wyhash64

        static inline void wyhash64_set_seed( uint64_t & state, uint64_t seed ) {
                state = seed;
                wyhash64( state );                                                              // prime
        } // wyhash64_set_seed
#endif // __SIZEOF_INT128__

//--------------------------------------------------
static inline uint64_t xorshift_13_7_17( uint64_t & state ) {
        uint64_t ret = state;
        state ^= state << 13;
        state ^= state >> 7;
        state ^= state << 17;
        return ret;
} // xorshift_13_7_17

static inline void xorshift_13_7_17_set_seed( uint64_t & state, uint64_t seed ) {
        state = seed;
        xorshift_13_7_17( state );                                                      // prime
} // xorshift_13_7_17_set_seed

//--------------------------------------------------
// Marsaglia shift-XOR PRNG with thread-local state
// Period is 4G-1
// 0 is absorbing and must be avoided
// Low-order bits are not particularly random
static inline uint32_t xorshift_6_21_7( uint32_t & state ) {
        uint32_t ret = state;
        state ^= state << 6;
        state ^= state >> 21;
        state ^= state << 7;
        return ret;
} // xorshift_6_21_7

static inline void xorshift_6_21_7_set_seed( uint32_t & state, uint32_t seed ) {
        state = seed;
        xorshift_6_21_7( state );                                                       // prime
} // xorshift_6_21_7_set_seed

//--------------------------------------------------
// The state must be seeded with a nonzero value.
static inline uint64_t xorshift_12_25_27( uint64_t & state ) {
        uint64_t ret = state;
        state ^= state >> 12;
        state ^= state << 25;
        state ^= state >> 27;
        return ret * 0x_2545_F491_4F6C_DD1D;
} // xorshift_12_25_27

static inline void xorshift_12_25_27_set_seed( uint64_t & state, uint64_t seed ) {
        state = seed;
        xorshift_12_25_27( state );                                                     // prime
} // xorshift_12_25_27_set_seed

//--------------------------------------------------
// The state must be seeded with a nonzero value.
#ifndef KISS_64
typedef struct { uint64_t z, w, jsr, jcong; } kiss_64_t;
#endif // ! KISS_64

static inline uint64_t kiss_64( kiss_64_t & rs ) with(rs) {
        kiss_64_t ret = rs;
        z = 36969 * (z & 65535) + (z >> 16);
        w = 18000 * (w & 65535) + (w >> 16);
        jsr ^= (jsr << 13);
        jsr ^= (jsr >> 17);
        jsr ^= (jsr << 5);
        jcong = 69069 * jcong + 1234567;
        return (((ret.z << 16) + ret.w) ^ ret.jcong) + ret.jsr;
} // kiss_64

static inline void kiss_64_set_seed( kiss_64_t & rs, uint64_t seed ) with(rs) {
        z = 1; w = 1; jsr = 4; jcong = seed;
        kiss_64( rs );                                                                          // prime
} // kiss_64_set_seed

//--------------------------------------------------
// The state array must be initialized to non-zero in the first four words.
#ifndef XORWOW
typedef struct { uint32_t a, b, c, d, counter; } xorwow_t;
#endif // ! XORWOW

static inline uint32_t xorwow( xorwow_t & rs ) with(rs) {
        // Algorithm "xorwow" from p. 5 of Marsaglia, "Xorshift RNGs".
        uint32_t ret = a + counter;
        uint32_t t = d;

        uint32_t const s = a;
        d = c;
        c = b;
        b = s;

        t ^= t >> 2;
        t ^= t << 1;
        t ^= s ^ (s << 4);
        a = t;
        counter += 362437;
        return ret;
} // xorwow

static inline void xorwow_set_seed( xorwow_t & rs, uint32_t seed ) {
        rs = (xorwow_t){ seed, seed, seed, seed, 0 };
        xorwow( rs );                                                                           // prime
} // xorwow_set_seed

//--------------------------------------------------
// Used in __tls_rand_fwd
#define M  (1_l64u << 48_l64u)
#define A  (25214903917_l64u)
#define AI (18446708753438544741_l64u)
#define C  (11_l64u)
#define D  (16_l64u)

// Bi-directional LCG random-number generator
static inline uint32_t LCGBI_fwd( uint64_t & rs ) {
        rs = (A * rs + C) & (M - 1);
        return rs >> D;
} // LCGBI_fwd

static inline uint32_t LCGBI_bck( uint64_t & rs ) {
        unsigned int r = rs >> D;
        rs = AI * (rs - C) & (M - 1);
        return r;
} // LCGBI_bck

#undef M
#undef A
#undef AI
#undef C
#undef D

#endif // __cforall