From eaef30eb49148e3a2415a7b8dd1d0fc13c7175ca Mon Sep 17 00:00:00 2001
From: Hayden Kroepfl <perlpowers@gmail.com>
Date: Sat, 6 Jan 2018 18:53:35 -0700
Subject: [PATCH] Added Inc and Dec instructions based off Add code

---
 .../assembly/DefaultInstructionSet.java       |  2 ++
 .../assembly/instruction/DecInstruction.java  | 32 +++++++++++++++++++
 .../assembly/instruction/IncInstruction.java  | 32 +++++++++++++++++++
 3 files changed, 66 insertions(+)
 create mode 100644 Server/src/main/java/net/simon987/server/assembly/instruction/DecInstruction.java
 create mode 100644 Server/src/main/java/net/simon987/server/assembly/instruction/IncInstruction.java

diff --git a/Server/src/main/java/net/simon987/server/assembly/DefaultInstructionSet.java b/Server/src/main/java/net/simon987/server/assembly/DefaultInstructionSet.java
index 43fffab..445db18 100755
--- a/Server/src/main/java/net/simon987/server/assembly/DefaultInstructionSet.java
+++ b/Server/src/main/java/net/simon987/server/assembly/DefaultInstructionSet.java
@@ -44,6 +44,8 @@ public class DefaultInstructionSet implements InstructionSet {
         add(new RclInstruction());
         add(new RcrInstruction());
         add(new SarInstruction());
+        add(new IncInstruction());
+        add(new DecInstruction());
     }
 
     /**
diff --git a/Server/src/main/java/net/simon987/server/assembly/instruction/DecInstruction.java b/Server/src/main/java/net/simon987/server/assembly/instruction/DecInstruction.java
new file mode 100644
index 0000000..29a3ddb
--- /dev/null
+++ b/Server/src/main/java/net/simon987/server/assembly/instruction/DecInstruction.java
@@ -0,0 +1,32 @@
+package net.simon987.server.assembly.instruction;
+
+import net.simon987.server.assembly.Instruction;
+import net.simon987.server.assembly.Status;
+import net.simon987.server.assembly.Target;
+import net.simon987.server.assembly.Util;
+
+public class DecInstruction extends Instruction {
+
+    public static final int OPCODE = 0x2B;
+
+    public DecInstruction() {
+        super("dec", OPCODE);
+    }
+
+    @Override
+    public Status execute(Target dst, int dstIndex, Status status) {
+        char a = (char) dst.get(dstIndex);
+        int result = a - 1;
+
+        // Like x86 Carry flag is preserved during INC/DEC 
+        // (Use ADD x, 1 to have carry flag change)
+        // Other flags set according to result
+        status.setSignFlag(Util.checkSign16(result));
+        status.setZeroFlag((char) result == 0);
+        status.setOverflowFlag(Util.checkOverFlowSub16(a, 1));
+    
+        dst.set(dstIndex, result);
+        return status;
+    }
+}
+
diff --git a/Server/src/main/java/net/simon987/server/assembly/instruction/IncInstruction.java b/Server/src/main/java/net/simon987/server/assembly/instruction/IncInstruction.java
new file mode 100644
index 0000000..05c5fa4
--- /dev/null
+++ b/Server/src/main/java/net/simon987/server/assembly/instruction/IncInstruction.java
@@ -0,0 +1,32 @@
+package net.simon987.server.assembly.instruction;
+
+import net.simon987.server.assembly.Instruction;
+import net.simon987.server.assembly.Status;
+import net.simon987.server.assembly.Target;
+import net.simon987.server.assembly.Util;
+
+public class IncInstruction extends Instruction {
+
+    public static final int OPCODE = 0x2A;
+
+    public IncInstruction() {
+        super("inc", OPCODE);
+    }
+
+    @Override
+    public Status execute(Target dst, int dstIndex, Status status) {
+        char a = (char) dst.get(dstIndex);
+        int result = a + 1;
+
+        // Like x86 Carry flag is preserved during INC/DEC
+        // (Use ADD x, 1 to have carry flag change)
+        // Other flags set according to result
+        status.setSignFlag(Util.checkSign16(result));
+        status.setZeroFlag((char) result == 0);
+        status.setOverflowFlag(Util.checkOverFlowAdd16(a, 1));
+    
+        dst.set(dstIndex, result);
+        return status;
+    }
+}
+