fnv32/lib/fnv32.js

FNV (Fowler–Noll–Vo) 32 bit hash function - FNV-1, FNV-1a.

"use strict";
//
// fnv32
//
// Version: 0.0.1
// Author: Mark W. B. Ashcroft (mark [at] fluidecho [dot] com)
// License: MIT or Apache 2.0.
//
// Copyright (c) 2017 Mark W. B. Ashcroft.
// Copyright (c) 2017 FluidEcho.
//



var FNV = function () {
  this.offset_basis = 2166136261;    // The prime, 32 bit offset_basis = 2,166,136,261 = 0x811C9DC5.	
};
module.exports = new FNV();


FNV.prototype.fnv_1 = function ( data ) {

  if ( typeof data === 'string' ) {
    data = new Buffer(data);
  }

  if ( !Buffer.isBuffer(data) ) {
    throw new Error('fnv32 input must be a String or Buffer.');
  }

  var hashint = this.offset_basis;

  for ( var i = 0; i < data.length; i++ ) {
    hashint += (hashint << 1) + (hashint << 4) + (hashint << 7) + (hashint << 8) + (hashint << 24);
    hashint = hashint ^ data[i];
  }

  return hashint >>> 0;    // unsigned 32 bit integer.

};


FNV.prototype.fnv_1a = function ( data ) {

  if ( typeof data === 'string' ) {
    data = new Buffer(data);
  }

  if ( !Buffer.isBuffer(data) ) {
    throw new Error('fnv32 input must be a String or Buffer.');
  }

  var hashint = this.offset_basis;

  for ( var i = 0; i < data.length; i++ ) {
    hashint = hashint ^ data[i];
    hashint += (hashint << 1) + (hashint << 4) + (hashint << 7) + (hashint << 8) + (hashint << 24);
  }

  return hashint >>> 0;    // unsigned 32 bit integer.

};


// To be compatible with: https://tools.ietf.org/html/draft-eastlake-fnv-12#page-6
FNV.prototype.toBufferLE = function ( hashint ) {

  if ( typeof hashint != 'number' ) {
    throw new Error('fnv32.toBufferLE input must be a Number.');
  }

  var buf = new Buffer(4);
  buf[0] = hashint & 0xff;
  buf[1] = hashint >>> 8 & 0xff;
  buf[2] = hashint >>> 16 & 0xff;
  buf[3] = hashint >>> 24 & 0xff;

  return buf;    // 32 bit little endian Buffer.
  
};