dadd(), dmul(): Implement

1 files changed, 47 insertions, 4 deletions

diff --git a/lib/decmath.js b/lib/decmath.js
index d32cf1d..fbb4e9e 100644
--- a/lib/decmath.js
+++ b/lib/decmath.js
@@ -33,14 +33,57 @@
 
 function dadd(a, b)
 {
-	/* TODO: Implement */
-	return a + b;
+	//console.log(a + " + " + b);
+	a = a.toString().split(".", 2);
+	b = b.toString().split(".", 2);
+	if (typeof a[1] == "undefined") a[1] = "";
+	if (typeof b[1] == "undefined") b[1] = "";
+	//console.log("ai: " + a[0] + ", af: " + a[1]);
+	//console.log("bi: " + b[0] + ", bf: " + b[1]);
+	var ce;
+	if (a[1].length == b[1].length) {
+		ce = a[1].length;
+	} else if (a[1].length < b[1].length) {
+		//console.log("padding af with " + (b[1].length - a[1].length) +
+		//		" zeroes");
+		a[1] += Array(b[1].length - a[1].length + 1).join("0");
+		ce = b[1].length;
+	} else {
+		//console.log("padding bf with " + (a[1].length - b[1].length) +
+		//		" zeroes");
+		b[1] += Array(a[1].length - b[1].length + 1).join("0");
+		ce = a[1].length;
+	}
+	//console.log("after padding:");
+	//console.log("ai: " + a[0] + ", af: " + a[1]);
+	//console.log("bi: " + b[0] + ", bf: " + b[1]);
+	var as = a[0] + a[1];
+	var bs = b[0] + b[1];
+	//console.log("as: " + as + ", ae: " + a[1].length);
+	//console.log("bs: " + bs + ", be: " + b[1].length);
+	var cs = (parseInt(as, 10) + parseInt(bs, 10)).toString();
+	//console.log("cs: " + cs + ", ce: " + ce);
+	//console.log(ce);
+	//console.log(cs.length);
+	//console.log(ce - cs.length + 1);
+	var pad = ce - cs.length;
+	if (pad > 0) cs = (Array(pad + 1).join("0") + cs).toString();
+	return cs.substr(0, cs.length - ce) + "." + cs.substr(cs.length - ce);
 }
 
 function dmul(a, b)
 {
-	/* TODO: Implement */
-	return a * b;
+	a = a.toString().split(".", 2);
+	b = b.toString().split(".", 2);
+	if (typeof a[1] == "undefined") a[1] = "";
+	if (typeof b[1] == "undefined") b[1] = "";
+	var as = a[0] + a[1];
+	var bs = b[0] + b[1];
+	var cs = (parseInt(as, 10) * parseInt(bs, 10)).toString();
+	var ce = a[1].length + b[1].length;
+	var pad = ce - cs.length;
+	if (pad > 0) cs = (Array(pad + 1).join("0") + cs).toString();
+	return cs.substr(0, cs.length - ce) + "." + cs.substr(cs.length - ce);
 }
 
 function drhtz(a, p)