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/*
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------------------------------------------------------------------------------
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Licensing information can be found at the end of the file.
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------------------------------------------------------------------------------
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rnd.h - v1.0 - Pseudo-random number generators for C/C++.
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Do this:
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#define RND_IMPLEMENTATION
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before you include this file in *one* C/C++ file to create the implementation.
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*/
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#ifndef rnd_h
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#define rnd_h
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#ifndef RND_U32
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#define RND_U32 unsigned int
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#endif
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#ifndef RND_U64
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#define RND_U64 unsigned long long
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#endif
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typedef struct rnd_pcg_t { RND_U64 state[ 2 ]; } rnd_pcg_t;
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void rnd_pcg_seed( rnd_pcg_t* pcg, RND_U32 seed );
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RND_U32 rnd_pcg_next( rnd_pcg_t* pcg );
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float rnd_pcg_nextf( rnd_pcg_t* pcg );
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int rnd_pcg_range( rnd_pcg_t* pcg, int min, int max );
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typedef struct rnd_well_t { RND_U32 state[ 17 ]; } rnd_well_t;
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void rnd_well_seed( rnd_well_t* well, RND_U32 seed );
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RND_U32 rnd_well_next( rnd_well_t* well );
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float rnd_well_nextf( rnd_well_t* well );
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int rnd_well_range( rnd_well_t* well, int min, int max );
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typedef struct rnd_gamerand_t { RND_U32 state[ 2 ]; } rnd_gamerand_t;
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void rnd_gamerand_seed( rnd_gamerand_t* gamerand, RND_U32 seed );
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RND_U32 rnd_gamerand_next( rnd_gamerand_t* gamerand );
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float rnd_gamerand_nextf( rnd_gamerand_t* gamerand );
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int rnd_gamerand_range( rnd_gamerand_t* gamerand, int min, int max );
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typedef struct rnd_xorshift_t { RND_U64 state[ 2 ]; } rnd_xorshift_t;
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void rnd_xorshift_seed( rnd_xorshift_t* xorshift, RND_U64 seed );
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RND_U64 rnd_xorshift_next( rnd_xorshift_t* xorshift );
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float rnd_xorshift_nextf( rnd_xorshift_t* xorshift );
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int rnd_xorshift_range( rnd_xorshift_t* xorshift, int min, int max );
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#endif /* rnd_h */
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/**
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rnd.h
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=====
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Pseudo-random number generators for C/C++.
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Example
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-------
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A basic example showing how to use the PCG set of random functions.
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#define RND_IMPLEMENTATION
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#include "rnd.h"
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#include <stdio.h> // for printf
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#include <time.h> // for time
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int main( int argc, char** argv ) {
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rnd_pcg_t pcg;
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rnd_pcg_seed( &pcg, 0u ); // initialize generator
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// print a handful of random integers
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// these will be the same on every run, as we
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// seeded the rng with a fixed value
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for( int i = 0; i < 5; ++i ) {
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RND_U32 n = rnd_pcg_next( &pcg );
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printf( "%08x, ", n );
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}
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printf( "\n" );
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// reseed with a value which is different on each run
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time_t seconds;
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time( &seconds );
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rnd_pcg_seed( &pcg, (RND_U32) seconds );
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// print another handful of random integers
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// these will be different on every run
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for( int i = 0; i < 5; ++i ) {
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RND_U32 n = rnd_pcg_next( &pcg );
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printf( "%08x, ", n );
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}
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printf( "\n" );
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// print a handful of random floats
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for( int i = 0; i < 5; ++i ) {
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float f = rnd_pcg_nextf( &pcg );
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printf( "%f, ", f );
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}
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printf( "\n" );
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// print random integers in the range 1 to 6
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for( int i = 0; i < 15; ++i ) {
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int r = rnd_pcg_range( &pcg, 1, 6 );
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printf( "%d, ", r );
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}
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printf( "\n" );
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return 0;
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}
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API Documentation
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-----------------
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rnd.h is a single-header library, and does not need any .lib files or other binaries, or any build scripts. To use it,
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you just include rnd.h to get the API declarations. To get the definitions, you must include rnd.h from *one* single C
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or C++ file, and #define the symbol `RND_IMPLEMENTATION` before you do.
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The library is meant for general-purpose use, such as games and similar apps. It is not meant to be used for
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cryptography and similar use cases.
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### Customization
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rnd.h allows for specifying the exact type of 32 and 64 bit unsigned integers to be used in its API. By default, these
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default to `unsigned int` and `unsigned long long`, but can be redefined by #defining RND_U32 and RND_U64 respectively
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before including rnd.h. This is useful if you, for example, use the types from `<stdint.h>` in the rest of your program,
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and you want rnd.h to use compatible types. In this case, you would include rnd.h using the following code:
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#define RND_U32 uint32_t
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#define RND_U64 uint64_t
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#include "rnd.h"
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Note that when customizing the data type, you need to use the same definition in every place where you include rnd.h,
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as it affect the declarations as well as the definitions.
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### The generators
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The library includes four different generators: PCG, WELL, GameRand and XorShift. They all have different
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characteristics, and you might want to use them for different things. GameRand is very fast, but does not give a great
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distribution or period length. XorShift is the only one returning a 64-bit value. WELL is an improvement of the often
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used Mersenne Twister, and has quite a large internal state. PCG is small, fast and has a small state. If you don't
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have any specific reason, you may default to using PCG.
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All generators expose their internal state, so it is possible to save this state and later restore it, to resume the
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random sequence from the same point.
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#### PCG - Permuted Congruential Generator
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PCG is a family of simple fast space-efficient statistically good algorithms for random number generation. Unlike many
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general-purpose RNGs, they are also hard to predict.
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More information can be found here:
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http://www.pcg-random.org/
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#### WELL - Well Equidistributed Long-period Linear
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Random number generation, using the WELL algorithm by F. Panneton, P. L'Ecuyer and M. Matsumoto.
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More information in the original paper:
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http://www.iro.umontreal.ca/~panneton/WELLRNG.html
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This code is originally based on WELL512 C/C++ code written by Chris Lomont (published in Game Programming Gems 7)
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and placed in the public domain.
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http://lomont.org/Math/Papers/2008/Lomont_PRNG_2008.pdf
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#### GameRand
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Based on the random number generator by Ian C. Bullard:
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http://www.redditmirror.cc/cache/websites/mjolnirstudios.com_7yjlc/mjolnirstudios.com/IanBullard/files/79ffbca75a75720f066d491e9ea935a0-10.html
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GameRand is a random number generator based off an "Image of the Day" posted by Stephan Schaem. More information here:
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http://www.flipcode.com/archives/07-15-2002.shtml
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#### XorShift
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A random number generator of the type LFSR (linear feedback shift registers). This specific implementation uses the
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XorShift+ variation, and returns 64-bit random numbers.
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More information can be found here:
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https://en.wikipedia.org/wiki/Xorshift
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rnd_pcg_seed
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------------
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void rnd_pcg_seed( rnd_pcg_t* pcg, RND_U32 seed )
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Initialize a PCG generator with the specified seed. The generator is not valid until it's been seeded.
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rnd_pcg_next
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------------
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RND_U32 rnd_pcg_next( rnd_pcg_t* pcg )
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Returns a random number N in the range: 0 <= N <= 0xffffffff, from the specified PCG generator.
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rnd_pcg_nextf
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-------------
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float rnd_pcg_nextf( rnd_pcg_t* pcg )
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Returns a random float X in the range: 0.0f <= X < 1.0f, from the specified PCG generator.
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rnd_pcg_range
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-------------
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int rnd_pcg_range( rnd_pcg_t* pcg, int min, int max )
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Returns a random integer N in the range: min <= N <= max, from the specified PCG generator.
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rnd_well_seed
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-------------
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void rnd_well_seed( rnd_well_t* well, RND_U32 seed )
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Initialize a WELL generator with the specified seed. The generator is not valid until it's been seeded.
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rnd_well_next
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-------------
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RND_U32 rnd_well_next( rnd_well_t* well )
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Returns a random number N in the range: 0 <= N <= 0xffffffff, from the specified WELL generator.
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rnd_well_nextf
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--------------
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float rnd_well_nextf( rnd_well_t* well )
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Returns a random float X in the range: 0.0f <= X < 1.0f, from the specified WELL generator.
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rnd_well_range
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--------------
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int rnd_well_range( rnd_well_t* well, int min, int max )
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Returns a random integer N in the range: min <= N <= max, from the specified WELL generator.
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rnd_gamerand_seed
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-----------------
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void rnd_gamerand_seed( rnd_gamerand_t* gamerand, RND_U32 seed )
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Initialize a GameRand generator with the specified seed. The generator is not valid until it's been seeded.
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rnd_gamerand_next
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-----------------
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RND_U32 rnd_gamerand_next( rnd_gamerand_t* gamerand )
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Returns a random number N in the range: 0 <= N <= 0xffffffff, from the specified GameRand generator.
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rnd_gamerand_nextf
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------------------
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float rnd_gamerand_nextf( rnd_gamerand_t* gamerand )
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Returns a random float X in the range: 0.0f <= X < 1.0f, from the specified GameRand generator.
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rnd_gamerand_range
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------------------
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int rnd_gamerand_range( rnd_gamerand_t* gamerand, int min, int max )
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Returns a random integer N in the range: min <= N <= max, from the specified GameRand generator.
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rnd_xorshift_seed
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-----------------
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void rnd_xorshift_seed( rnd_xorshift_t* xorshift, RND_U64 seed )
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Initialize a XorShift generator with the specified seed. The generator is not valid until it's been seeded.
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rnd_xorshift_next
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-----------------
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RND_U64 rnd_xorshift_next( rnd_xorshift_t* xorshift )
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Returns a random number N in the range: 0 <= N <= 0xffffffffffffffff, from the specified XorShift generator.
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rnd_xorshift_nextf
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------------------
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float rnd_xorshift_nextf( rnd_xorshift_t* xorshift )
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Returns a random float X in the range: 0.0f <= X < 1.0f, from the specified XorShift generator.
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rnd_xorshift_range
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------------------
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int rnd_xorshift_range( rnd_xorshift_t* xorshift, int min, int max )
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Returns a random integer N in the range: min <= N <= max, from the specified XorShift generator.
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*/
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/*
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----------------------
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IMPLEMENTATION
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----------------------
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*/
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#ifdef RND_IMPLEMENTATION
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#undef RND_IMPLEMENTATION
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// Convert a randomized RND_U32 value to a float value x in the range 0.0f <= x < 1.0f. Contributed by Jonatan Hedborg
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static float rnd_internal_float_normalized_from_u32( RND_U32 value )
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{
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RND_U32 exponent = 127;
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RND_U32 mantissa = value >> 9;
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RND_U32 result = ( exponent << 23 ) | mantissa;
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float fresult = *(float*)( &result );
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return fresult - 1.0f;
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}
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static RND_U32 rnd_internal_murmur3_avalanche32( RND_U32 h )
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{
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h ^= h >> 16;
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h *= 0x85ebca6b;
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h ^= h >> 13;
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h *= 0xc2b2ae35;
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h ^= h >> 16;
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return h;
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}
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static RND_U64 rnd_internal_murmur3_avalanche64( RND_U64 h )
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{
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h ^= h >> 33;
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h *= 0xff51afd7ed558ccd;
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h ^= h >> 33;
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h *= 0xc4ceb9fe1a85ec53;
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h ^= h >> 33;
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return h;
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}
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void rnd_pcg_seed( rnd_pcg_t* pcg, RND_U32 seed )
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{
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RND_U64 value = ( ( (RND_U64) seed ) << 1ULL ) | 1ULL;
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value = rnd_internal_murmur3_avalanche64( value );
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pcg->state[ 0 ] = 0U;
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pcg->state[ 1 ] = ( value << 1ULL ) | 1ULL;
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rnd_pcg_next( pcg );
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pcg->state[ 0 ] += rnd_internal_murmur3_avalanche64( value );
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rnd_pcg_next( pcg );
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}
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RND_U32 rnd_pcg_next( rnd_pcg_t* pcg )
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{
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RND_U64 oldstate = pcg->state[ 0 ];
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pcg->state[ 0 ] = oldstate * 0x5851f42d4c957f2dULL + pcg->state[ 1 ];
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RND_U32 xorshifted = (RND_U32)( ( ( oldstate >> 18ULL) ^ oldstate ) >> 27ULL );
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RND_U32 rot = (RND_U32)( oldstate >> 59ULL );
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return ( xorshifted >> rot ) | ( xorshifted << ( ( -(int) rot ) & 31 ) );
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}
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float rnd_pcg_nextf( rnd_pcg_t* pcg )
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{
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return rnd_internal_float_normalized_from_u32( rnd_pcg_next( pcg ) );
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}
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int rnd_pcg_range( rnd_pcg_t* pcg, int min, int max )
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{
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int const range = ( max - min ) + 1;
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if( range <= 0 ) return min;
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int const value = (int) ( rnd_pcg_nextf( pcg ) * range );
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return min + value;
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}
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void rnd_well_seed( rnd_well_t* well, RND_U32 seed )
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{
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RND_U32 value = rnd_internal_murmur3_avalanche32( ( seed << 1U ) | 1U );
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well->state[ 16 ] = 0;
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well->state[ 0 ] = value ^ 0xf68a9fc1U;
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for( int i = 1; i < 16; ++i )
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well->state[ i ] = ( 0x6c078965U * ( well->state[ i - 1 ] ^ ( well->state[ i - 1 ] >> 30 ) ) + i );
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}
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RND_U32 rnd_well_next( rnd_well_t* well )
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{
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RND_U32 a = well->state[ well->state[ 16 ] ];
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RND_U32 c = well->state[ ( well->state[ 16 ] + 13 ) & 15 ];
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RND_U32 b = a ^ c ^ ( a << 16 ) ^ ( c << 15 );
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c = well->state[ ( well->state[ 16 ] + 9 ) & 15 ];
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c ^= ( c >> 11 );
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a = well->state[ well->state[ 16 ] ] = b ^ c;
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RND_U32 d = a ^ ( ( a << 5 ) & 0xda442d24U );
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well->state[ 16 ] = (well->state[ 16 ] + 15 ) & 15;
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a = well->state[ well->state[ 16 ] ];
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well->state[ well->state[ 16 ] ] = a ^ b ^ d ^ ( a << 2 ) ^ ( b << 18 ) ^ ( c << 28 );
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return well->state[ well->state[ 16 ] ];
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}
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float rnd_well_nextf( rnd_well_t* well )
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{
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return rnd_internal_float_normalized_from_u32( rnd_well_next( well ) );
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}
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int rnd_well_range( rnd_well_t* well, int min, int max )
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{
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int const range = ( max - min ) + 1;
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if( range <= 0 ) return min;
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int const value = (int) ( rnd_well_nextf( well ) * range );
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return min + value;
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}
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void rnd_gamerand_seed( rnd_gamerand_t* gamerand, RND_U32 seed )
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{
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RND_U32 value = rnd_internal_murmur3_avalanche32( ( seed << 1U ) | 1U );
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gamerand->state[ 0 ] = value;
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gamerand->state[ 1 ] = value ^ 0x49616e42U;
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}
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RND_U32 rnd_gamerand_next( rnd_gamerand_t* gamerand )
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{
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gamerand->state[ 0 ] = ( gamerand->state[ 0 ] << 16 ) + ( gamerand->state[ 0 ] >> 16 );
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gamerand->state[ 0 ] += gamerand->state[ 1 ];
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gamerand->state[ 1 ] += gamerand->state[ 0 ];
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return gamerand->state[ 0 ];
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}
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float rnd_gamerand_nextf( rnd_gamerand_t* gamerand )
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{
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return rnd_internal_float_normalized_from_u32( rnd_gamerand_next( gamerand ) );
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}
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int rnd_gamerand_range( rnd_gamerand_t* gamerand, int min, int max )
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{
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int const range = ( max - min ) + 1;
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if( range <= 0 ) return min;
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int const value = (int) ( rnd_gamerand_nextf( gamerand ) * range );
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return min + value;
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}
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void rnd_xorshift_seed( rnd_xorshift_t* xorshift, RND_U64 seed )
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{
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RND_U64 value = rnd_internal_murmur3_avalanche64( ( seed << 1ULL ) | 1ULL );
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xorshift->state[ 0 ] = value;
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value = rnd_internal_murmur3_avalanche64( value );
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xorshift->state[ 1 ] = value;
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}
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RND_U64 rnd_xorshift_next( rnd_xorshift_t* xorshift )
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{
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RND_U64 x = xorshift->state[ 0 ];
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RND_U64 const y = xorshift->state[ 1 ];
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xorshift->state[ 0 ] = y;
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x ^= x << 23;
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x ^= x >> 17;
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x ^= y ^ ( y >> 26 );
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xorshift->state[ 1 ] = x;
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return x + y;
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}
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float rnd_xorshift_nextf( rnd_xorshift_t* xorshift )
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{
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return rnd_internal_float_normalized_from_u32( (RND_U32)( rnd_xorshift_next( xorshift ) >> 32 ) );
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}
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int rnd_xorshift_range( rnd_xorshift_t* xorshift, int min, int max )
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{
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int const range = ( max - min ) + 1;
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if( range <= 0 ) return min;
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int const value = (int) ( rnd_xorshift_nextf( xorshift ) * range );
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return min + value;
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}
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#endif /* RND_IMPLEMENTATION */
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/*
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contributors:
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Jonatan Hedborg (unsigned int to normalized float conversion)
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revision history:
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1.0 first publicly released version
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*/
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/*
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------------------------------------------------------------------------------
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This software is available under 2 licenses - you may choose the one you like.
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Based on public domain implementation - original licenses can be found next to
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the relevant implementation sections of this file.
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------------------------------------------------------------------------------
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ALTERNATIVE A - MIT License
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Copyright (c) 2016 Mattias Gustavsson
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Permission is hereby granted, free of charge, to any person obtaining a copy of
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this software and associated documentation files (the "Software"), to deal in
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the Software without restriction, including without limitation the rights to
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use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
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of the Software, and to permit persons to whom the Software is furnished to do
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so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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|
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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------------------------------------------------------------------------------
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ALTERNATIVE B - Public Domain (www.unlicense.org)
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This is free and unencumbered software released into the public domain.
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Anyone is free to copy, modify, publish, use, compile, sell, or distribute this
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software, either in source code form or as a compiled binary, for any purpose,
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commercial or non-commercial, and by any means.
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In jurisdictions that recognize copyright laws, the author or authors of this
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software dedicate any and all copyright interest in the software to the public
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domain. We make this dedication for the benefit of the public at large and to
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the detriment of our heirs and successors. We intend this dedication to be an
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overt act of relinquishment in perpetuity of all present and future rights to
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this software under copyright law.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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------------------------------------------------------------------------------
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*/
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Cameron Murphy Reikes