diff --git a/vm/src/execution_engine/engine.rs b/vm/src/execution_engine/engine.rs
index 1a0d41e6..c2eb5211 100644
--- a/vm/src/execution_engine/engine.rs
+++ b/vm/src/execution_engine/engine.rs
@@ -1,4 +1,5 @@
 use crate::error::Error;
+use crate::execution_engine::opcode::*;
 use crate::method_area::java_method::JavaMethod;
 use crate::method_area::method_area::MethodArea;
 
@@ -17,50 +18,50 @@ impl<'a> Engine<'a> {
                 .ok_or(Error::new_execution("Error getting stack frame"))?;
 
             match stack_frame.get_bytecode_byte() {
-                3 => {
+                ICONST_0 => {
                     println!("ICONST_0");
                     stack_frame.push(0);
 
                     stack_frame.incr_pc();
                 }
-                4 => {
+                ICONST_1 => {
                     println!("ICONST_1");
                     stack_frame.push(1);
 
                     stack_frame.incr_pc();
                 }
-                5 => {
+                ICONST_2 => {
                     println!("ICONST_2");
                     stack_frame.push(2);
 
                     stack_frame.incr_pc();
                 }
-                6 => {
+                ICONST_3 => {
                     println!("ICONST_3");
                     stack_frame.push(3);
 
                     stack_frame.incr_pc();
                 }
-                7 => {
+                ICONST_4 => {
                     println!("ICONST_4");
                     stack_frame.push(4);
 
                     stack_frame.incr_pc();
                 }
-                8 => {
+                ICONST_5 => {
                     println!("ICONST_5");
                     stack_frame.push(5);
 
                     stack_frame.incr_pc();
                 }
-                16 => {
+                BIPUSH => {
                     println!("BIPUSH");
                     stack_frame.incr_pc();
                     stack_frame.push(stack_frame.get_bytecode_byte() as i32);
 
                     stack_frame.incr_pc();
                 }
-                17 => {
+                SIPUSH => {
                     println!("SIPUSH");
                     stack_frame.incr_pc();
                     let high = stack_frame.get_bytecode_byte() as u16;
@@ -72,7 +73,7 @@ impl<'a> Engine<'a> {
 
                     stack_frame.incr_pc();
                 }
-                21 => {
+                ILOAD => {
                     println!("ILOAD");
                     stack_frame.incr_pc();
                     let pos = stack_frame.get_bytecode_byte() as usize;
@@ -82,35 +83,35 @@ impl<'a> Engine<'a> {
 
                     stack_frame.incr_pc();
                 }
-                26 => {
+                ILOAD_0 => {
                     println!("ILOAD_0");
                     let val = stack_frame.get_local(0);
                     stack_frame.push(val);
 
                     stack_frame.incr_pc();
                 }
-                27 => {
+                ILOAD_1 => {
                     println!("ILOAD_1");
                     let val = stack_frame.get_local(1);
                     stack_frame.push(val);
 
                     stack_frame.incr_pc();
                 }
-                28 => {
+                ILOAD_2 => {
                     println!("ILOAD_2");
                     let val = stack_frame.get_local(2);
                     stack_frame.push(val);
 
                     stack_frame.incr_pc();
                 }
-                29 => {
+                ILOAD_3 => {
                     println!("ILOAD_3");
                     let val = stack_frame.get_local(3);
                     stack_frame.push(val);
 
                     stack_frame.incr_pc();
                 }
-                54 => {
+                ISTORE => {
                     println!("ISTORE");
                     stack_frame.incr_pc();
                     let pos = stack_frame.get_bytecode_byte() as usize;
@@ -121,35 +122,35 @@ impl<'a> Engine<'a> {
 
                     stack_frame.incr_pc();
                 }
-                59 => {
+                ISTORE_0 => {
                     println!("ISTORE_0");
                     let val = stack_frame.pop();
                     stack_frame.set_local(0, val);
 
                     stack_frame.incr_pc();
                 }
-                60 => {
+                ISTORE_1 => {
                     println!("ISTORE_1");
                     let val = stack_frame.pop();
                     stack_frame.set_local(1, val);
 
                     stack_frame.incr_pc();
                 }
-                61 => {
+                ISTORE_2 => {
                     println!("ISTORE_2");
                     let val = stack_frame.pop();
                     stack_frame.set_local(2, val);
 
                     stack_frame.incr_pc();
                 }
-                62 => {
+                ISTORE_3 => {
                     println!("ISTORE_3");
                     let val = stack_frame.pop();
                     stack_frame.set_local(3, val);
 
                     stack_frame.incr_pc();
                 }
-                96 => {
+                IADD => {
                     println!("IADD");
                     let b = stack_frame.pop();
                     let a = stack_frame.pop();
@@ -157,7 +158,7 @@ impl<'a> Engine<'a> {
 
                     stack_frame.incr_pc();
                 }
-                100 => {
+                ISUB => {
                     let b = stack_frame.pop();
                     let a = stack_frame.pop();
                     let result = a - b;
@@ -166,7 +167,7 @@ impl<'a> Engine<'a> {
                     stack_frame.incr_pc();
                     println!("ISUB -> {a} - {b} = {result}");
                 }
-                104 => {
+                IMUL => {
                     let b = stack_frame.pop();
                     let a = stack_frame.pop();
                     let result = a * b;
@@ -175,7 +176,7 @@ impl<'a> Engine<'a> {
                     stack_frame.incr_pc();
                     println!("IMUL -> {a} * {b} = {result}");
                 }
-                112 => {
+                IREM => {
                     println!("IREM");
                     let b = stack_frame.pop();
                     let a = stack_frame.pop();
@@ -183,7 +184,7 @@ impl<'a> Engine<'a> {
 
                     stack_frame.incr_pc();
                 }
-                132 => {
+                IINC => {
                     stack_frame.incr_pc();
                     let index = stack_frame.get_bytecode_byte() as usize;
 
@@ -197,7 +198,7 @@ impl<'a> Engine<'a> {
                     stack_frame.incr_pc();
                     println!("IINC -> {current_val} + {const_val} = {new_val}");
                 }
-                153 => {
+                IFEQ => {
                     println!("IFEQ");
 
                     let value1 = stack_frame.pop();
@@ -212,7 +213,7 @@ impl<'a> Engine<'a> {
                         stack_frame.advance_pc(3);
                     }
                 }
-                154 => {
+                IFNE => {
                     println!("IFNE");
 
                     let value1 = stack_frame.pop();
@@ -227,7 +228,7 @@ impl<'a> Engine<'a> {
                         stack_frame.advance_pc(3);
                     }
                 }
-                160 => {
+                IF_ICMPNE => {
                     println!("IF_ICMPNE");
 
                     let value2 = stack_frame.pop();
@@ -243,7 +244,7 @@ impl<'a> Engine<'a> {
                         stack_frame.advance_pc(3);
                     }
                 }
-                161 => {
+                IF_ICMPLT => {
                     println!("IF_ICMPLT");
 
                     let value2 = stack_frame.pop();
@@ -259,7 +260,7 @@ impl<'a> Engine<'a> {
                         stack_frame.advance_pc(3);
                     }
                 }
-                162 => {
+                IF_ICMPGE => {
                     println!("IF_ICMPGE");
 
                     let value2 = stack_frame.pop();
@@ -275,7 +276,7 @@ impl<'a> Engine<'a> {
                         stack_frame.advance_pc(3);
                     }
                 }
-                163 => {
+                IF_ICMPGT => {
                     println!("IF_ICMPGT");
 
                     let value2 = stack_frame.pop();
@@ -291,7 +292,7 @@ impl<'a> Engine<'a> {
                         stack_frame.advance_pc(3);
                     }
                 }
-                167 => {
+                GOTO => {
                     println!("GOTO");
 
                     let branchbyte1 = stack_frame.get_bytecode_byte_1() as u16;
@@ -300,7 +301,7 @@ impl<'a> Engine<'a> {
 
                     stack_frame.advance_pc(offset);
                 }
-                172 => {
+                IRETURN => {
                     println!(
                         "IRETURN -> locals={:?}, operand_stack={:?}",
                         stack_frame.locals, stack_frame.operand_stack
@@ -312,7 +313,7 @@ impl<'a> Engine<'a> {
                         .ok_or(Error::new_execution("Error getting stack last value"))?
                         .push(ret);
                 }
-                177 => {
+                RETURN => {
                     println!(
                         "RETURN -> locals={:?}, operand_stack={:?}",
                         stack_frame.locals, stack_frame.operand_stack
@@ -326,7 +327,7 @@ impl<'a> Engine<'a> {
                     stack_frames.pop(); // Return from method, pop the current frame
                                         // add more logic here
                 }
-                184 => {
+                INVOKESTATIC => {
                     println!(
                         "INVOKESTATIC -> locals={:?}, operand_stack={:?}",
                         stack_frame.locals, stack_frame.operand_stack
diff --git a/vm/src/execution_engine/mod.rs b/vm/src/execution_engine/mod.rs
index b7d19a64..e5f94e66 100644
--- a/vm/src/execution_engine/mod.rs
+++ b/vm/src/execution_engine/mod.rs
@@ -1 +1,2 @@
 pub(crate) mod engine;
+pub(crate) mod opcode;
diff --git a/vm/src/execution_engine/opcode.rs b/vm/src/execution_engine/opcode.rs
new file mode 100644
index 00000000..0c75ba7d
--- /dev/null
+++ b/vm/src/execution_engine/opcode.rs
@@ -0,0 +1,207 @@
+#![allow(dead_code)]
+
+pub(crate) const NOP: u8 = 0;
+pub(crate) const ACONST_NULL: u8 = 1;
+pub(crate) const ICONST_M1: u8 = 2;
+pub(crate) const ICONST_0: u8 = 3;
+pub(crate) const ICONST_1: u8 = 4;
+pub(crate) const ICONST_2: u8 = 5;
+pub(crate) const ICONST_3: u8 = 6;
+pub(crate) const ICONST_4: u8 = 7;
+pub(crate) const ICONST_5: u8 = 8;
+pub(crate) const LCONST_0: u8 = 9;
+pub(crate) const LCONST_1: u8 = 10;
+pub(crate) const FCONST_0: u8 = 11;
+pub(crate) const FCONST_1: u8 = 12;
+pub(crate) const FCONST_2: u8 = 13;
+pub(crate) const DCONST_0: u8 = 14;
+pub(crate) const DCONST_1: u8 = 15;
+pub(crate) const BIPUSH: u8 = 16;
+pub(crate) const SIPUSH: u8 = 17;
+pub(crate) const LDC: u8 = 18;
+pub(crate) const LDC_W: u8 = 19;
+pub(crate) const LDC2_W: u8 = 20;
+pub(crate) const ILOAD: u8 = 21;
+pub(crate) const LLOAD: u8 = 22;
+pub(crate) const FLOAD: u8 = 23;
+pub(crate) const DLOAD: u8 = 24;
+pub(crate) const ALOAD: u8 = 25;
+pub(crate) const ILOAD_0: u8 = 26;
+pub(crate) const ILOAD_1: u8 = 27;
+pub(crate) const ILOAD_2: u8 = 28;
+pub(crate) const ILOAD_3: u8 = 29;
+pub(crate) const LLOAD_0: u8 = 30;
+pub(crate) const LLOAD_1: u8 = 31;
+pub(crate) const LLOAD_2: u8 = 32;
+pub(crate) const LLOAD_3: u8 = 33;
+pub(crate) const FLOAD_0: u8 = 34;
+pub(crate) const FLOAD_1: u8 = 35;
+pub(crate) const FLOAD_2: u8 = 36;
+pub(crate) const FLOAD_3: u8 = 37;
+pub(crate) const DLOAD_0: u8 = 38;
+pub(crate) const DLOAD_1: u8 = 39;
+pub(crate) const DLOAD_2: u8 = 40;
+pub(crate) const DLOAD_3: u8 = 41;
+pub(crate) const ALOAD_0: u8 = 42;
+pub(crate) const ALOAD_1: u8 = 43;
+pub(crate) const ALOAD_2: u8 = 44;
+pub(crate) const ALOAD_3: u8 = 45;
+pub(crate) const IALOAD: u8 = 46;
+pub(crate) const LALOAD: u8 = 47;
+pub(crate) const FALOAD: u8 = 48;
+pub(crate) const DALOAD: u8 = 49;
+pub(crate) const AALOAD: u8 = 50;
+pub(crate) const BALOAD: u8 = 51;
+pub(crate) const CALOAD: u8 = 52;
+pub(crate) const SALOAD: u8 = 53;
+pub(crate) const ISTORE: u8 = 54;
+pub(crate) const LSTORE: u8 = 55;
+pub(crate) const FSTORE: u8 = 56;
+pub(crate) const DSTORE: u8 = 57;
+pub(crate) const ASTORE: u8 = 58;
+pub(crate) const ISTORE_0: u8 = 59;
+pub(crate) const ISTORE_1: u8 = 60;
+pub(crate) const ISTORE_2: u8 = 61;
+pub(crate) const ISTORE_3: u8 = 62;
+pub(crate) const LSTORE_0: u8 = 63;
+pub(crate) const LSTORE_1: u8 = 64;
+pub(crate) const LSTORE_2: u8 = 65;
+pub(crate) const LSTORE_3: u8 = 66;
+pub(crate) const FSTORE_0: u8 = 67;
+pub(crate) const FSTORE_1: u8 = 68;
+pub(crate) const FSTORE_2: u8 = 69;
+pub(crate) const FSTORE_3: u8 = 70;
+pub(crate) const DSTORE_0: u8 = 71;
+pub(crate) const DSTORE_1: u8 = 72;
+pub(crate) const DSTORE_2: u8 = 73;
+pub(crate) const DSTORE_3: u8 = 74;
+pub(crate) const ASTORE_0: u8 = 75;
+pub(crate) const ASTORE_1: u8 = 76;
+pub(crate) const ASTORE_2: u8 = 77;
+pub(crate) const ASTORE_3: u8 = 78;
+pub(crate) const IASTORE: u8 = 79;
+pub(crate) const LASTORE: u8 = 80;
+pub(crate) const FASTORE: u8 = 81;
+pub(crate) const DASTORE: u8 = 82;
+pub(crate) const AASTORE: u8 = 83;
+pub(crate) const BASTORE: u8 = 84;
+pub(crate) const CASTORE: u8 = 85;
+pub(crate) const SASTORE: u8 = 86;
+pub(crate) const POP: u8 = 87;
+pub(crate) const POP2: u8 = 88;
+pub(crate) const DUP: u8 = 89;
+pub(crate) const DUP_X1: u8 = 90;
+pub(crate) const DUP_X2: u8 = 91;
+pub(crate) const DUP2: u8 = 92;
+pub(crate) const DUP2_X1: u8 = 93;
+pub(crate) const DUP2_X2: u8 = 94;
+pub(crate) const SWAP: u8 = 95;
+pub(crate) const IADD: u8 = 96;
+pub(crate) const LADD: u8 = 97;
+pub(crate) const FADD: u8 = 98;
+pub(crate) const DADD: u8 = 99;
+pub(crate) const ISUB: u8 = 100;
+pub(crate) const LSUB: u8 = 101;
+pub(crate) const FSUB: u8 = 102;
+pub(crate) const DSUB: u8 = 103;
+pub(crate) const IMUL: u8 = 104;
+pub(crate) const LMUL: u8 = 105;
+pub(crate) const FMUL: u8 = 106;
+pub(crate) const DMUL: u8 = 107;
+pub(crate) const IDIV: u8 = 108;
+pub(crate) const LDIV: u8 = 109;
+pub(crate) const FDIV: u8 = 110;
+pub(crate) const DDIV: u8 = 111;
+pub(crate) const IREM: u8 = 112;
+pub(crate) const LREM: u8 = 113;
+pub(crate) const FREM: u8 = 114;
+pub(crate) const DREM: u8 = 115;
+pub(crate) const INEG: u8 = 116;
+pub(crate) const LNEG: u8 = 117;
+pub(crate) const FNEG: u8 = 118;
+pub(crate) const DNEG: u8 = 119;
+pub(crate) const ISHL: u8 = 120;
+pub(crate) const LSHL: u8 = 121;
+pub(crate) const ISHR: u8 = 122;
+pub(crate) const LSHR: u8 = 123;
+pub(crate) const IUSHR: u8 = 124;
+pub(crate) const LUSHR: u8 = 125;
+pub(crate) const IAND: u8 = 126;
+pub(crate) const LAND: u8 = 127;
+pub(crate) const IOR: u8 = 128;
+pub(crate) const LOR: u8 = 129;
+pub(crate) const IXOR: u8 = 130;
+pub(crate) const LXOR: u8 = 131;
+pub(crate) const IINC: u8 = 132;
+pub(crate) const I2L: u8 = 133;
+pub(crate) const I2F: u8 = 134;
+pub(crate) const I2D: u8 = 135;
+pub(crate) const L2I: u8 = 136;
+pub(crate) const L2F: u8 = 137;
+pub(crate) const L2D: u8 = 138;
+pub(crate) const F2I: u8 = 139;
+pub(crate) const F2L: u8 = 140;
+pub(crate) const F2D: u8 = 141;
+pub(crate) const D2I: u8 = 142;
+pub(crate) const D2L: u8 = 143;
+pub(crate) const D2F: u8 = 144;
+pub(crate) const I2B: u8 = 145;
+pub(crate) const I2C: u8 = 146;
+pub(crate) const I2S: u8 = 147;
+pub(crate) const LCMP: u8 = 148;
+pub(crate) const FCMPL: u8 = 149;
+pub(crate) const FCMPG: u8 = 150;
+pub(crate) const DCMPL: u8 = 151;
+pub(crate) const DCMPG: u8 = 152;
+pub(crate) const IFEQ: u8 = 153;
+pub(crate) const IFNE: u8 = 154;
+pub(crate) const IFLT: u8 = 155;
+pub(crate) const IFGE: u8 = 156;
+pub(crate) const IFGT: u8 = 157;
+pub(crate) const IFLE: u8 = 158;
+pub(crate) const IF_ICMPEQ: u8 = 159;
+pub(crate) const IF_ICMPNE: u8 = 160;
+pub(crate) const IF_ICMPLT: u8 = 161;
+pub(crate) const IF_ICMPGE: u8 = 162;
+pub(crate) const IF_ICMPGT: u8 = 163;
+pub(crate) const IF_ICMPLE: u8 = 164;
+pub(crate) const IF_ACMPEQ: u8 = 165;
+pub(crate) const IF_ACMPNE: u8 = 166;
+pub(crate) const GOTO: u8 = 167;
+pub(crate) const JSR: u8 = 168;
+pub(crate) const RET: u8 = 169;
+pub(crate) const TABLESWITCH: u8 = 170;
+pub(crate) const LOOKUPSWITCH: u8 = 171;
+pub(crate) const IRETURN: u8 = 172;
+pub(crate) const LRETURN: u8 = 173;
+pub(crate) const FRETURN: u8 = 174;
+pub(crate) const DRETURN: u8 = 175;
+pub(crate) const ARETURN: u8 = 176;
+pub(crate) const RETURN: u8 = 177;
+pub(crate) const GETSTATIC: u8 = 178;
+pub(crate) const PUTSTATIC: u8 = 179;
+pub(crate) const GETFIELD: u8 = 180;
+pub(crate) const PUTFIELD: u8 = 181;
+pub(crate) const INVOKEVIRTUAL: u8 = 182;
+pub(crate) const INVOKESPECIAL: u8 = 183;
+pub(crate) const INVOKESTATIC: u8 = 184;
+pub(crate) const INVOKEINTERFACE: u8 = 185;
+pub(crate) const INVOKEDYNAMIC: u8 = 186;
+pub(crate) const NEW: u8 = 187;
+pub(crate) const NEWARRAY: u8 = 188;
+pub(crate) const ANEWARRAY: u8 = 189;
+pub(crate) const ARRAYLENGTH: u8 = 190;
+pub(crate) const ATHROW: u8 = 191;
+pub(crate) const CHECKCAST: u8 = 192;
+pub(crate) const INSTANCEOF: u8 = 193;
+pub(crate) const MONITORENTER: u8 = 194;
+pub(crate) const MONITOREXIT: u8 = 195;
+pub(crate) const WIDE: u8 = 196;
+pub(crate) const MULTIANEWARRAY: u8 = 197;
+pub(crate) const IFNULL: u8 = 198;
+pub(crate) const IFNONNULL: u8 = 199;
+pub(crate) const GOTO_W: u8 = 200;
+pub(crate) const JSR_W: u8 = 201;
+pub(crate) const BREAKPOINT: u8 = 202;
+pub(crate) const IMPDEP1: u8 = 254;
+pub(crate) const IMPDEP2: u8 = 255;