Added a sentence validation to the utilities

index.js

@@ -6,25 +6,46 @@
 
   utils.RATIOS = {
     // DISTANCE
-    NM_IN_KM: 1.852000000000000000000000000000000000000000000000000000000000000000000000000,
-    KM_IN_NM: 0.539956803000000000000000000000000000000000000000000000000000000000000000000000000,
+    NM_IN_KM: 1.852,
+    KM_IN_NM: 0.539956803,
     // SPEED
     // Knots
-    KNOTS_IN_MS: 0.514444000000000000000000000000000000000000000000000000000000000000000000000000,
-    KNOTS_IN_MPH: 1.150779000000000000000000000000000000000000000000000000000000000000000000000000,
-    KNOTS_IN_KPH: 1.852000000000000000000000000000000000000000000000000000000000000000000000000,
+    KNOTS_IN_MS: 0.514444,
+    KNOTS_IN_MPH: 1.150779,
+    KNOTS_IN_KPH: 1.852,
     // MPH
-    MPH_IN_MS: 0.44704000000000000000000000000000000000000000000000000000000000000000000000000,
-    MPH_IN_KPH: 1.609344000000000000000000000000000000000000000000000000000000000000000000000000,
-    MPH_IN_KNOTS: 0.868976000000000000000000000000000000000000000000000000000000000000000000000000,
+    MPH_IN_MS: 0.44704,
+    MPH_IN_KPH: 1.609344,
+    MPH_IN_KNOTS: 0.868976,
     // KPH
-    KPH_IN_MS: 0.277778000000000000000000000000000000000000000000000000000000000000000000000000,
-    KPH_IN_MPH: 0.621371000000000000000000000000000000000000000000000000000000000000000000000000,
-    KPH_IN_KNOTS: 0.539957000000000000000000000000000000000000000000000000000000000000000000000000,
+    KPH_IN_MS: 0.277778,
+    KPH_IN_MPH: 0.621371,
+    KPH_IN_KNOTS: 0.539957,
     // MS
-    MS_IN_KPH: 3.6000000000000000000000000000000000000000000000000000000000000000000000000,
-    MS_IN_MPH: 2.236936000000000000000000000000000000000000000000000000000000000000000000000000,
-    MS_IN_KNOTS: 1.943844000000000000000000000000000000000000000000000000000000000000000000000000,
+    MS_IN_KPH: 3.6,
+    MS_IN_MPH: 2.236936,
+    MS_IN_KNOTS: 1.943844,
+  };
+
+  exports.valid = function(sentence) {
+    sentence = String(sentence).trim();
+
+    if (sentence === "") {
+      return false;
+    }
+
+    if ((sentence.charAt(0) == '$' || sentence.charAt(0) == '!') && sentence.charAt(sentence.length - 3) == '*') {
+      var check = 0;
+      var split = sentence.split('*');
+
+      for (var i = 1; i < split[0].length; i++) {
+        check = check ^ split[0].charCodeAt(i);
+      };
+
+      return (parseInt(split[1], 16) == check);
+    }
+
+    return false;
   };
 
   exports.source = function(sentence) {