johnny-five/lib/fn.js

The JavaScript Arduino Programming Framework.

var lodash = require("lodash"),
  Fn = {
    assign: lodash.assign,
    extend: lodash.extend,
    defaults: lodash.defaults,
    debounce: lodash.debounce,
    cloneDeep: lodash.cloneDeep,
    mixin: lodash.mixin
  };

// Fn.fmap( val, fromLow, fromHigh, toLow, toHigh )
//
// Re-maps a number from one range to another.
// Based on arduino map()
//
// Return float
Fn.fmap = function(value, fromLow, fromHigh, toLow, toHigh) {
  return (value - fromLow) * (toHigh - toLow) /
    (fromHigh - fromLow) + toLow;
};

// Alias
Fn.fscale = Fn.fmap;

// Fn.map( val, fromLow, fromHigh, toLow, toHigh )
//
// Re-maps a number from one range to another.
// Based on arduino map()
//
// Retun int
Fn.map = function(value, fromLow, fromHigh, toLow, toHigh) {
  return Fn.fmap(value, fromLow, fromHigh, toLow, toHigh) | 0;
};

// Alias
Fn.scale = Fn.map;

// Fn.constrain( val, lower, upper )
//
// Constrains a number to be within a range.
// Based on arduino constrain()
Fn.constrain = function(value, lower, upper) {
  return Math.min(upper, Math.max(lower, value));
};

// Fn.range( upper )
// Fn.range( lower, upper )
// Fn.range( lower, upper, tick )
//
// Returns a new array range
//
Fn.range = function(lower, upper, tick) {

  if (arguments.length === 1) {
    upper = lower - 1;
    lower = 0;
  }

  lower = lower || 0;
  upper = upper || 0;
  tick = tick || 1;

  var len = Math.max(Math.ceil((upper - lower) / tick), 0),
    idx = 0,
    range = [];

  while (idx <= len) {
    range[idx++] = lower;
    lower += tick;
  }

  return range;
};

// Fn.range.prefixed( prefix, upper )
// Fn.range.prefixed( prefix, lower, upper )
// Fn.range.prefixed( prefix, lower, upper, tick )
//
// Returns a new array range, each value prefixed
//
Fn.range.prefixed = function(prefix, lower, upper, tick) {
  return Fn.range.apply(null, [].slice.call(arguments, 1)).map(function(val) {
    return prefix + val;
  });
};

// Fn.uid()
//
// Returns a reasonably unique id string
//
Fn.uid = function() {
  return "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx".replace(/[xy]/g, function(chr) {
    var rnd = Math.random() * 16 | 0;
    return (chr === "x" ? rnd : (rnd & 0x3 | 0x8)).toString(16);
  }).toUpperCase();
};

// Fn.square()
//
// Returns squared x
//
Fn.square = function(x) {
  return x * x;
};


Fn.sum = function sum(values) {
  return values.reduce(function(accum, value) {
    return accum + value;
  }, 0);
};

// fma function
// Copyright (c) 2012, Jens Nockert
// All rights reserved.
Fn.fma = function(a, b, c) {
  var aHigh = 134217729 * a;
  var aLow;

  aHigh = aHigh + (a - aHigh);
  aLow = a - aHigh;

  var bHigh = 134217729 * b;
  var bLow;

  bHigh = bHigh + (b - bHigh);
  bLow = b - bHigh;

  var r1 = a * b;
  var r2 = -r1 + aHigh * bHigh + aHigh * bLow + aLow * bHigh + aLow * bLow;

  var s = r1 + c;
  var t = (r1 - (s - c)) + (c - (s - r1));

  return s + (t + r2);
};
// end fma function copyright


// Fn._BV(bit)
//
// (from avr/io.h; "BV" => Bit Value)
//
// Return byte value with that bit set.
//
Fn._BV = Fn.bitValue = Fn.bv = function(bit) {
  return 1 << bit;
};

/*
  Example of _BV/bitValue usage...

  Logically OR these bits together:
  var ORed = _BV(0) | _BV(2) | _BV(7);

  BIT         7  6  5  4  3  2  1  0
  ---------------------------------------------------------
  _BV(0)  =   0  0  0  0  0  0  0  1
  _BV(2)  =   0  0  0  0  0  1  0  0
  _BV(7)  =   1  0  0  0  0  0  0  0
  ORed    =   1  0  0  0  0  1  0  1

  ORed === 133;

*/


module.exports = Fn;