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pachanka/Seed.js

Created June 22, 2016 01:17
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  1. pachanka created this gist Jun 22, 2016.
    95 changes: 95 additions & 0 deletions Seed.js
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,95 @@
    /* I MADE THIS, I THINK ITS AWESOME */

    /* Seed generation and shuffle */
    var Seed_int = 0;
    var Seed_str = '';
    var Seed = {
    /* Generate a random number, or perpetuate
    a pseudo-random seed if it is provided. */
    random_int : function(seed_int){
    var rand = 0;
    if(typeof seed_int == 'number'){
    // A linear congruential generator
    var multiplier = 1103515245;
    var increment = 12345;
    var modulus = Math.pow(2, 31); // 2^31
    rand = ((multiplier * seed_int + increment) % modulus );
    //seed_int++;
    }else{
    // Create seed
    if(typeof window.crypto !== 'undefined'
    && typeof window.crypto.getRandomValues === 'function'){
    // Sweeet crypto API
    var rand_arr = new Uint32Array(1);
    window.crypto.getRandomValues(rand_arr);
    rand = rand_arr[0];
    }else{
    // Insecure!
    rand = Math.floor(Math.random() * 10000000000);
    }
    }
    return rand;
    },

    /* Can generate an integer from a string. */
    int_from_string : function(str){
    var hash = 0;
    var len = str.length;
    if (len == 0) return hash;
    for (i = 0; i < len; i++) {
    var ch = str.charCodeAt(i);
    hash = ( (hash << 5) - hash) + ch;
    hash = hash & hash; // Convert to 32bit integer
    }
    return hash;
    },


    /*
    - len is desired string length
    - corpus is the available characters to construct the output
    - seed is a number */
    string_from_seed : function(len, corpus, seed){
    var text = '';
    // Make sure corpus is at len lenght.
    if(len > corpus.length){
    for (var i = 0; i < len; i++) {
    corpus += corpus.charAt(i);
    };
    }
    return Seed.shuffle_string(corpus, seed).substring(0, len);
    },

    /*
    - corpus: the string to shuffle
    - seed: is an integer */
    shuffle_string : function(corpus, seed) {
    var a = corpus.split(''),
    n = a.length;

    for(var i = n - 1; i > 0; i--) {
    var j = Seed.random_int(seed) % (i + 1);
    var tmp = a[i];
    a[i] = a[j];
    a[j] = tmp;
    }
    return a.join('');
    },

    /* reset seed globals */
    reset_seed : function(){
    Seed_int = 0;
    Seed_str = '';
    },

    set_seed : function(seed_obj){
    Seed_str = seed_obj.str;
    Seed_int = seed_obj.int;
    return seed_obj;
    },

    make_seed_str : function(len,corpus){
    //Seed.reset_seed();
    return Seed.string_from_seed(len, corpus, Seed.random_int());
    },
    };