shashi/example/2-hash-fill-example.js

Shashi, a simple module to generate, using pseudo-randomness, a universal family/set of hash functions, which produce integer values within the selected range (a prime number)..

/*
 * Shashi simple example, generate 2 hash function,
 * filling with data produced by Math.random.
 */

var log = console.log
    , Shashi = require( '../' )
    // items to hash
    , i = 7
    // how many random hash function to generate
    , h = 2
    // a prime to define range for seed sequence values (range = prime - 1)
    , p = 104729
    , result = Shashi( h, i, p )
    , ufn = result[ 0 ]
    , seed = result[ 1 ]
    // selected range for input values is [0-12]
    , r = 13
    // use a sequence for input
    , input = new Buffer( [ 0, 0, 0, 0, 12, 12, 12 ] )
    // get 2 hash functions, reading only 1 byte at the time from input buffer
    , v0 = ufn( 0, input, 1 )
    , v1 = ufn( 1, input, 1 )
    ;

log();
log( '- %d hash functions generated with data produced by Math.random()', h );
log();
log( '- input buffer:', input );
log( '  > tot items:', i );
log( '  > val range: [%d,%d]', 0, r -1 );
log( '  > item size: %d bytes', 1 );
log( '  > tot bytes: %d bytes', input.length );
log();
log( '- seed seq buffer:' );
log( '  > tot items: %d ', seed.items );
log( '  > seq prime:', p );
log( '  > val range: [%d,%d]', 0, p -1 );
log( '  > item size: %d bytes', seed.ibytes );
log( '  > tot bytes: %d bytes', seed.result.length );
log();
log( '- hash results:', v0, v1 );
log();