From c9ed9e17207ce93bdc2bea60e908ad12e15ba2c4 Mon Sep 17 00:00:00 2001
From: Andrew Keeton <andrewrkeeton@gmail.com>
Date: Thu, 6 Nov 2014 19:48:48 -0500
Subject: [PATCH 1/3] Add branch_if_equal_test().

---
 src/machine.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/machine.rs b/src/machine.rs
index 1b90a47..aeee90b 100644
--- a/src/machine.rs
+++ b/src/machine.rs
@@ -910,6 +910,18 @@ fn branch_if_carry_set_test() {
     assert_eq!(machine.registers.program_counter, Address(0xABCD));
 }
 
+#[test]
+fn branch_if_equal_test() {
+    let mut machine = Machine::new();
+
+    machine.branch_if_equal(Address(0xABCD));
+    assert_eq!(machine.registers.program_counter, Address(0));
+
+    machine.registers.status.or(PS_ZERO);
+    machine.branch_if_equal(Address(0xABCD));
+    assert_eq!(machine.registers.program_counter, Address(0xABCD));
+}
+
 #[test]
 fn branch_if_minus_test() {
     {

From 8febc747889d3c9a40227da96c2663b26763b7e4 Mon Sep 17 00:00:00 2001
From: Andrew Keeton <andrewrkeeton@gmail.com>
Date: Thu, 6 Nov 2014 19:49:54 -0500
Subject: [PATCH 2/3] Add branch_if_equal().

---
 src/machine.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/machine.rs b/src/machine.rs
index aeee90b..d36b3e0 100644
--- a/src/machine.rs
+++ b/src/machine.rs
@@ -565,6 +565,12 @@ impl Machine {
         }
     }
 
+    fn branch_if_equal(&mut self, addr: Address) {
+        if self.registers.status.contains(PS_ZERO) {
+            self.registers.program_counter = addr;
+        }
+    }
+
     fn branch_if_minus(&mut self, addr: Address) {
         if self.registers.status.contains(PS_NEGATIVE) {
             self.registers.program_counter = addr;

From a0ad2d47be1376daca9812e385af066b421e9483 Mon Sep 17 00:00:00 2001
From: Andrew Keeton <andrewrkeeton@gmail.com>
Date: Thu, 6 Nov 2014 19:50:35 -0500
Subject: [PATCH 3/3] Add BEQ to execute_instruction().

---
 src/machine.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/machine.rs b/src/machine.rs
index d36b3e0..5372e3d 100644
--- a/src/machine.rs
+++ b/src/machine.rs
@@ -122,6 +122,12 @@ impl Machine {
                 self.branch_if_carry_set(addr);
             }
 
+            (instruction::BEQ, instruction::UseRelative(rel)) => {
+                let addr = self.registers.program_counter
+                         + AddressDiff(rel as i32);
+                self.branch_if_equal(addr);
+            }
+
             (instruction::BIT, instruction::UseAddress(addr)) => {
                 let a: u8 = self.registers.accumulator as u8;
                 let m: u8 = self.memory.get_byte(addr);