added while

README.md

@@ -46,7 +46,7 @@ the 64 bit ARM Instruction Set Architecture (ISA).
 | ------- | ------- |
 | 1 | [Hello World](./section_1/hello_world/README.md) |
 | 2 | [If Statements](./section_1/if/README.md) |
-
+| 3 | [While Loops](./section_1/while/README.md) |
 
 ## Section 2 - Stuff
 

section_1/while/README.md

@@ -0,0 +1,42 @@
+# While Loops
+
+## Overview
+
+We have already [covered](../if/README.md) the `if` statement. A `while` loop is exactly the same with the addition of at least one branch and a label. It really is that simple.
+
+To illustrate this, here is a flow chart of an `if` statement (on the left) compared to a `while` loop (on the right).
+
+![while loop](./while.jpeg)
+
+The closing brace in an `if` statement is indicated by the red arrow head. This isn't a branch, the code flow simply falls through to the statement beyond the closing brace. In the `while` loop, the behavior of the closing brace changes to be that of a branch back to just before the evaluation of the boolean condition (the "Decision").
+
+A new label is placed before evaluating the "Decision". 
+
+A new unconditional branch is placed after the end of the "Code Block."
+
+For review, here is the assembly language for an `if` statement:
+
+```asm
+    // Assume value of a is in x0                                       // 1 
+    // Assume value of b is in x1                                       // 2 
+    cmp     x0, x1                                                      // 3 
+    ble     1f                                                          // 4 
+    // CODE BLOCK                                                       // 5 
+1:                                                                      // 6 
+```
+
+Here is the code for the `while` showing one new label and one new unconditional branch:
+
+```asm
+    // Assume value of a is in x0                                       // 1 
+    // Assume value of b is in x1                                       // 2 
+                                                                        // 3 
+ 1: cmp     x0, x1                                                      // 4 
+    ble     2f                                                          // 5 
+    // CODE BLOCK                                                       // 6 
+    b       1b                                                          // 7 
+                                                                        // 8 
+2:                                                                      // 9 
+```
+
+Temporary label `2` on `line 9` takes the place of the line after the closing brace in a `while` loop.

section_1/while/if02.s

@@ -0,0 +1,9 @@
+    // Assume value of a is in x0
+    // Assume value of b is in x1
+ 
+ 1: cmp     x0, x1
+    ble     2f
+    // CODE BLOCK
+    b       1b
+    
+2: