From adec9f83f875da3586eadd0d8555a819801b7a43 Mon Sep 17 00:00:00 2001
From: Vipin Kumar <vipin.ind.kumar@gmail.com>
Date: Fri, 25 Aug 2017 14:24:24 +0000
Subject: [PATCH] Implement writeIf() in CodeWriter.java

---
 CodeWriter.java | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/CodeWriter.java b/CodeWriter.java
index 33051da..c291fd7 100644
--- a/CodeWriter.java
+++ b/CodeWriter.java
@@ -401,6 +401,21 @@ public void writeGoto(String label) {
     // Write Assembly code for the if-goto command
     public void writeIf(String label) {
         try {
+            // pop top-most value from stack
+            out.write("@SP");
+            out.newLine();
+            out.write("M = M - 1");
+            out.newLine();
+            out.write("A = M");
+            out.newLine();
+            out.write("D = M");
+            out.newLine();
+
+            // jump to the label, if the value is not equal to 0
+            out.write("@" + label);
+            out.newLine();
+            out.write("D;JNE");
+            out.newLine();
 
         }
         catch (IOException e) {