aleaPRNG-1.1.js

/*////////////////////////////////////////////////////////////////
aleaPRNG 1.1
//////////////////////////////////////////////////////////////////
https://github.com/macmcmeans/aleaPRNG/blob/master/aleaPRNG-1.1.js
//////////////////////////////////////////////////////////////////
Original work copyright © 2010 Johannes Baagøe, under MIT license
This is a derivative work copyright (c) 2017-2020, W. Mac" McMeans, under BSD license.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
////////////////////////////////////////////////////////////////*/
function aleaPRNG() {
    return( function( args ) {
        "use strict";

        const version = 'aleaPRNG 1.1.0';

        var s0
            , s1
            , s2
            , c
            , uinta = new Uint32Array( 3 )
            , initialArgs
            , mashver = ''
        ;

        /* private: initializes generator with specified seed */
        function _initState( _internalSeed ) {
            var mash = Mash();

            // internal state of generator
            s0 = mash( ' ' );
            s1 = mash( ' ' );
            s2 = mash( ' ' );

            c = 1;

            for( var i = 0; i < _internalSeed.length; i++ ) {
                s0 -= mash( _internalSeed[ i ] );
                if( s0 < 0 ) { s0 += 1; }

                s1 -= mash( _internalSeed[ i ] );
                if( s1 < 0 ) { s1 += 1; }
                
                s2 -= mash( _internalSeed[ i ] );
                if( s2 < 0 ) { s2 += 1; }
            }

            mashver = mash.version;

            mash = null;
        };

        /* private: dependent string hash function */
        function Mash() {
            var n = 4022871197; // 0xefc8249d

            var mash = function( data ) {
                data = data.toString();
                
                // cache the length
                for( var i = 0, l = data.length; i < l; i++ ) {
                    n += data.charCodeAt( i );
                    
                    var h = 0.02519603282416938 * n;
                    
                    n  = h >>> 0;
                    h -= n;
                    h *= n;
                    n  = h >>> 0;
                    h -= n;
                    n += h * 4294967296; // 0x100000000      2^32
                }
                return ( n >>> 0 ) * 2.3283064365386963e-10; // 2^-32
            };

            mash.version = 'Mash 0.9';
            return mash;
        };


        /* private: check if number is integer */
        function _isInteger( _int ) { 
            return parseInt( _int, 10 ) === _int; 
        };

        /* public: return a 32-bit fraction in the range [0, 1]
        This is the main function returned when aleaPRNG is instantiated
        */
        var random = function() {
            var t = 2091639 * s0 + c * 2.3283064365386963e-10; // 2^-32
            
            s0 = s1;
            s1 = s2;

            return s2 = t - ( c = t | 0 );
        };

        /* public: return a 53-bit fraction in the range [0, 1] */
        random.fract53 = function() {
            return random() + ( random() * 0x200000  | 0 ) * 1.1102230246251565e-16; // 2^-53
        };

        /* public: return an unsigned integer in the range [0, 2^32] */
        random.int32 = function() {
            return random() * 0x100000000; // 2^32
        };

        /* public: advance the generator the specified amount of cycles */
        random.cycle = function( _run ) {
            _run = typeof _run === 'undefined' ? 1 : +_run;
            if( _run < 1 ) { _run = 1; }
            for( var i = 0; i < _run; i++ ) { random(); }
        };

        /* public: return inclusive range */
        random.range = function() { 
            var loBound
                , hiBound
            ;
            
            if( arguments.length === 1 ) {
                loBound = 0;
                hiBound = arguments[ 0 ];

            } else {
                loBound = arguments[ 0 ];
                hiBound = arguments[ 1 ];
            }

            if( arguments[ 0 ] > arguments[ 1 ] ) { 
                loBound = arguments[ 1 ];
                hiBound = arguments[ 0 ];
            }

            // return integer
            if( _isInteger( loBound ) && _isInteger( hiBound ) ) { 
                return Math.floor( random() * ( hiBound - loBound + 1 ) ) + loBound; 

            // return float
            } else {
                return random() * ( hiBound - loBound ) + loBound; 
            }
        };

        /* public: initialize generator with the seed values used upon instantiation */
        random.restart = function() {
            _initState( initialArgs );
        };

        /* public: seeding function */
        random.seed = function() { 
            _initState( Array.prototype.slice.call( arguments ) );
        }; 

        /* public: show the version of the RNG */
        random.version = function() { 
            return version;
        }; 

        /* public: show the version of the RNG and the Mash string hasher */
        random.versions = function() { 
            return version + ', ' + mashver;
        }; 

        // when no seed is specified, create a random one from Windows Crypto (Monte Carlo application) 
        if( args.length === 0 ) {
             window.crypto.getRandomValues( uinta );
             args = [ uinta[ 0 ], uinta[ 1 ], uinta[ 2 ] ];
        };

        // store the seed used when the RNG was instantiated, if any
        initialArgs = args;

        // initialize the RNG
        _initState( args );

        return random;

    })( Array.prototype.slice.call( arguments ) );
};