Type correction and opcode implementations

src/bytecode.rs

@@ -25,12 +25,16 @@ impl Bytecode {
             0x0E => (Instruction::PushConstDouble0(), 1),
             0x0F => (Instruction::PushConstDouble1(), 1),
 
-            0x10 => (Instruction::LoadByteImmediate(self.bytes[offset+1]), 2),
+            0x10 => (Instruction::LoadByteImmediate(i8::from_be_bytes([self.bytes[offset+1]])), 2),
-            0x11 => (Instruction::LoadShortImmediate((self.bytes[offset+1] as u16) << 8 | self.bytes[offset+2] as u16), 3),
+            0x11 => {
+                let bytes = [self.bytes[offset+1], self.bytes[offset+2]];
+                (Instruction::LoadShortImmediate(i16::from_be_bytes(bytes)), 3)
+            }
             0x12 => (Instruction::LoadConstant(self.bytes[offset+1]), 2),
             0x13 => (Instruction::LoadCostantWide((self.bytes[offset+1] as u16) << 8 | self.bytes[offset+2] as u16), 3),
             0x14 => (Instruction::LoadConstant64((self.bytes[offset+1] as u16) << 8 | self.bytes[offset+2] as u16), 3),
 
+            0x19 => (Instruction::LoadLocalReference(self.bytes[offset+1]), 2),
             0x1A => (Instruction::LoadLocalInt0(), 1),
             0x1B => (Instruction::LoadLocalInt1(), 1),
             0x1C => (Instruction::LoadLocalInt2(), 1),
@@ -51,17 +55,19 @@ impl Bytecode {
             0x32 => (Instruction::ArrayElement(), 1),
             0x33 => (Instruction::LoadFromBArray(), 1),
             0x36 => (Instruction::StoreLocalInt(self.bytes[offset+1]), 2),
+            0x3A => (Instruction::StoreLocalReference(self.bytes[offset+1]), 2),
             0x3B => (Instruction::StoreLocalInt0(), 1),
             0x3C => (Instruction::StoreLocalInt1(), 1),
             0x3D => (Instruction::StoreLocalInt2(), 1),
             0x3E => (Instruction::StoreLocalInt3(), 1),
-            0x4B => (Instruction::StoreReference0(), 1),
+            0x4B => (Instruction::StoreLocalReference0(), 1),
-            0x4C => (Instruction::StoreReference1(), 1),
+            0x4C => (Instruction::StoreLocalReference1(), 1),
-            0x4D => (Instruction::StoreReference2(), 1),
+            0x4D => (Instruction::StoreLocalReference2(), 1),
-            0x4E => (Instruction::StoreReference3(), 1),
+            0x4E => (Instruction::StoreLocalReference3(), 1),
 
             0x53 => (Instruction::StoreIntoRArray(), 1),
             0x54 => (Instruction::StoreIntoBArray(), 1),
+            0x55 => (Instruction::StoreIntoCArray(), 1),
 
             0x57 => (Instruction::Pop(), 1),
             0x59 => (Instruction::Duplicate(), 1),
@@ -72,7 +78,8 @@ impl Bytecode {
             0x6C => (Instruction::DivideInt(), 1),
             0x6D => (Instruction::DivideLong(), 1),
 
-            0x7A => (Instruction::ShiftIntRight(), 1),
+            0x7A => (Instruction::ArithmeticShiftIntRight(), 1),
+            0x7C => (Instruction::LogicalShiftIntRight(), 1),
 
             0x80 => (Instruction::OrInt(), 1),
             0x84 => (Instruction::IncrementLocalInt(self.bytes[offset+1], i8::from_be_bytes([self.bytes[offset+2]])), 3),
@@ -136,13 +143,31 @@ impl Bytecode {
                 let bytes = [self.bytes[offset+1], self.bytes[offset+2]];
                 (Instruction::BranchReferenceInequality(i16::from_be_bytes(bytes)), 3)
             }
-
-            0xAC => (Instruction::ReturnInt(), 1),
             0xA7 => {
                 let bytes = [self.bytes[offset+1], self.bytes[offset+2]];
                 (Instruction::BranchAlways(i16::from_be_bytes(bytes)), 3)
             }
 
+            0xAB => {
+                let padding = 4 - (offset % 4) - 1;
+                let default_bytes = [self.bytes[offset+padding+1], self.bytes[offset+padding+2], self.bytes[offset+padding+3], self.bytes[offset+padding+4]];
+                let default = i32::from_be_bytes(default_bytes);
+
+                let npairs_bytes = [self.bytes[offset+padding+5], self.bytes[offset+padding+6], self.bytes[offset+padding+7], self.bytes[offset+padding+8]];
+                let npairs = i32::from_be_bytes(npairs_bytes);
+
+                let mut pairs_vec = Vec::with_capacity(npairs as usize);
+                for i in 0..npairs as usize {
+                    let match_bytes = [self.bytes[offset+padding+8*(1+i)+1], self.bytes[offset+padding+8*(1+i)+2], self.bytes[offset+padding+8*(1+i)+3], self.bytes[offset+padding+8*(1+i)+4]];
+                    let offset_bytes = [self.bytes[offset+padding+8*(1+i)+5], self.bytes[offset+padding+8*(1+i)+6], self.bytes[offset+padding+8*(1+i)+7], self.bytes[offset+padding+8*(1+i)+8]];
+
+                    pairs_vec.push((i32::from_be_bytes(match_bytes), i32::from_be_bytes(offset_bytes)));
+                }
+
+                (Instruction::LookupSwitch(default, pairs_vec.into()), 1 + padding + 4 + 4 + npairs as usize * 8)
+            }
+            0xAC => (Instruction::ReturnInt(), 1),
+
             0xB0 => (Instruction::ReturnReference(), 1),
             0xB1 => (Instruction::ReturnVoid(), 1),
             0xB2 => (Instruction::GetStatic((self.bytes[offset+1] as u16) << 8 | self.bytes[offset+2] as u16), 3),
@@ -217,12 +242,13 @@ pub enum Instruction {
     PushConstDouble0()                      = 0x0E, // Push 0.0
     PushConstDouble1()                      = 0x0F, // Push 1.0
 
-    LoadByteImmediate(u8)           = 0x10, // push immediate short
+    LoadByteImmediate(i8)                   = 0x10, // push immediate short
-    LoadShortImmediate(u16)         = 0x11, // push immediate short
+    LoadShortImmediate(i16)                 = 0x11, // push immediate short
     LoadConstant(u8)                        = 0x12, // Push from constant pool
     LoadCostantWide(u16)                    = 0x13, // Push from constant pool with wide index, don't load
                                                     // double or long or whatever
     LoadConstant64(u16)                     = 0x14, // Push Long or Double from constant pool
+    LoadLocalReference(u8)                  = 0x19, // Load reference from indexed local variable
     LoadLocalInt0()                         = 0x1A, // Load int from local variable
     LoadLocalInt1()                         = 0x1B, // Load int from local variable
     LoadLocalInt2()                         = 0x1C, // Load int from local variable
@@ -244,17 +270,19 @@ pub enum Instruction {
     ArrayElement()                          = 0x32, // load element from array
     LoadFromBArray()                        = 0x33, // store into byte array
     StoreLocalInt(u8)                       = 0x36, // store into indexed local variable
+    StoreLocalReference(u8)                 = 0x3A, // store into indexed local variable
     StoreLocalInt0()                        = 0x3B, // store int into local variable
     StoreLocalInt1()                        = 0x3C, // store int into local variable
     StoreLocalInt2()                        = 0x3D, // store int into local variable
     StoreLocalInt3()                        = 0x3E, // store int into local variable
-    StoreReference0()               = 0x4B, // store reference into local variable
+    StoreLocalReference0()                  = 0x4B, // store reference into local variable
-    StoreReference1()               = 0x4C, // store reference into local variable
+    StoreLocalReference1()                  = 0x4C, // store reference into local variable
-    StoreReference2()               = 0x4D, // store reference into local variable
+    StoreLocalReference2()                  = 0x4D, // store reference into local variable
-    StoreReference3()               = 0x4E, // store reference into local variable
+    StoreLocalReference3()                  = 0x4E, // store reference into local variable
 
     StoreIntoRArray()                       = 0x53, // store value into reference array
     StoreIntoBArray()                       = 0x54, // store value into byte or boolean array
+    StoreIntoCArray()                       = 0x55, // store value into char array
     Pop()                                   = 0x57, // Pop top stack value
     Duplicate()                             = 0x59, // duplicate top stack value
 
@@ -264,7 +292,8 @@ pub enum Instruction {
     DivideInt()                             = 0x6C, // integer division, round toward zero and more rules
     DivideLong()                            = 0x6D, // long division
 
-    ShiftIntRight()                 = 0x7a, // shift int
+    ArithmeticShiftIntRight()               = 0x7A, // shift int
+    LogicalShiftIntRight()                  = 0x7C, // shift int right with zero extension
 
     OrInt()                                 = 0x80, // value, value => or
     IncrementLocalInt(u8, i8)               = 0x84, // increment local variable by constant i8
@@ -288,6 +317,7 @@ pub enum Instruction {
     BranchReferenceInequality(i16)          = 0xA6,
 
     BranchAlways(i16)                       = 0xA7, // branch if true
+    LookupSwitch(i32, Box<[(i32, i32)]>)    = 0xAB, // offset based on switch value
     ReturnInt()                             = 0xAC, // return integer from function
 
     ReturnReference()                       = 0xB0, // return top-ref from current function

src/classstore.rs

@@ -156,10 +156,12 @@ impl ClassStore {
         };
 
         let compatible_count = CompatibleTypesIterator::new(my_type_index, self)
-            .filter(|type_name| *type_name == other_type_name)
+            .filter(|type_name| 
+                *type_name == other_type_name
+            )
             .count();
 
-        compatible_count == 0
+        compatible_count != 0
     }
 
     pub fn have_class(&self, classname: &String) -> bool {

src/heap_area.rs

@@ -79,14 +79,14 @@ impl HeapArea {
         let byte_array_ref = self.make_primitive_byte_array(utf16_bytes.len(), class_store);
 
         for (index, byte) in utf16_bytes.iter().enumerate() {
-            self.object_area.set_array_element(byte_array_ref, index, FieldValue::Byte(*byte));
+            self.object_area.set_array_element(byte_array_ref, index, FieldValue::Byte(i8::from_ne_bytes([*byte])));
         }
 
         let string_class_index = class_store.class_idx_from_name(&String::from("java/lang/String")).unwrap();
         let string_ref = self.make_object(class_store, string_class_index);
 
         self.object_area.set_object_field(string_ref, "value", FieldValue::Reference(byte_array_ref), string_class_index, class_store).unwrap();
-        const UTF16_CODER: u8 = 1; // TODO: I don't like this
+        const UTF16_CODER: i8 = 1; // TODO: I don't like this
         self.object_area.set_object_field(string_ref, "coder", FieldValue::Byte(UTF16_CODER), string_class_index, class_store).unwrap();
 
         string_ref 
@@ -104,6 +104,12 @@ impl HeapArea {
 pub struct ObjectReference(u32);
 
 
+impl Into<FieldValue> for ObjectReference {
+    fn into(self) -> FieldValue {
+        FieldValue::Reference(self)
+    }
+}
+
 impl ObjectReference {
     pub const NULL: ObjectReference = ObjectReference(0);
 }
@@ -125,7 +131,7 @@ impl ObjectArea {
     fn fill_byte_cache(&mut self, class_store: &ClassStore) -> usize {
         let byte_class_index = class_store.class_idx_from_name(&String::from("java/lang/Byte")).unwrap();
         let mut total_memory_usage = 0;
-        for byte in 0..=u8::MAX {
+        for byte in i8::MIN..=i8::MAX {
             let (byte_object_ref, object_memory) = self.make(class_store, byte_class_index);
             self.set_object_field(byte_object_ref, "value", FieldValue::Byte(byte), byte_class_index, class_store).unwrap();
 
@@ -154,7 +160,7 @@ impl ObjectArea {
 
         let array_object = ByteArray {
             class_ref: array_class_ref,
-            content: vec![0_u8; capacity].into(),
+            content: vec![0_i8; capacity].into(),
         };
 
         let array_ref = self.store_entry(CompartmentEntry::ByteArray(array_object));
@@ -350,12 +356,17 @@ impl ObjectArea {
                 let array_element = array.content.get_mut(index).unwrap();
 
                 *array_element = match element { FieldValue::Reference(r) => r, _ => unreachable!() } ;
-            },
+            }
             CompartmentEntry::ByteArray(array) => {
                 let array_element = array.content.get_mut(index).unwrap();
 
                 *array_element = match element { FieldValue::Byte(b) => b, _ => unreachable!() } ;
-            },
+            }
+            CompartmentEntry::CharArray(array) => {
+                let array_element = array.content.get_mut(index).unwrap();
+
+                *array_element = match element { FieldValue::Char(c) => c, _ => unreachable!() } ;
+            }
             _ => unreachable!(),
         };
 
@@ -508,7 +519,7 @@ pub struct CharArray {
 #[derive(Debug)]
 pub struct ByteArray {
     class_ref: ObjectReference,
-    content: Box<[u8]>,
+    content: Box<[i8]>,
 }
 
 #[derive(Debug)]
@@ -639,7 +650,7 @@ pub struct ObjectField {
 #[derive(Debug, Clone, Copy)]
 pub enum FieldValue {
     Boolean(bool),
-    Byte(u8),
+    Byte(i8),
     Char(u16),
     Short(i16),
     Int(i32),
@@ -674,7 +685,7 @@ impl FieldValue {
             AbstractTypeKind::Long()       => Self::Long(0),
             AbstractTypeKind::Classname(_) => Self::Reference(ObjectReference::NULL),
             AbstractTypeKind::Short()      => Self::Short(0),
-            AbstractTypeKind::Boolean()    => Self::Boolean(true),
+            AbstractTypeKind::Boolean()    => Self::Boolean(false),
         }
     }
 }

src/jvm.rs

@@ -553,7 +553,7 @@ impl JVM {
                             AbstractTypeKind::Byte() => {
                                 let int_entry = class_file.pool_int_entry(constant_value_info.constant_value_index)?;
 
-                                FieldValue::Byte(int_entry.value as u8)
+                                FieldValue::Byte(int_entry.value as i8)
                             },
                             AbstractTypeKind::Char() => {
                                 let int_entry = class_file.pool_int_entry(constant_value_info.constant_value_index)?;
@@ -678,6 +678,14 @@ impl JVM {
                     wrap_stackframe_error(class, method, frame.operand_stack.push(StackValue::Int(value_0 + value_1)))?;
                 }
 
+                Instruction::ArithmeticShiftIntRight() => {
+                    let shift = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))? as u8 & 0b00011111;
+                    let int   = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
+
+                    // rust does arithmetic shift on singed values
+                    wrap_stackframe_error(class, method, frame.operand_stack.push(StackValue::Int(int >> shift)))?;
+                },
+
                 Instruction::ArrayLength() => {
                     let array_reference = wrap_stackframe_error(class, method, frame.operand_stack.pop_reference(0))?;
 
@@ -740,6 +748,16 @@ impl JVM {
                     }
                 }
 
+                Instruction::BranchIntLessThan(branch_offset) => {
+                    let value_2 = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
+                    let value_1 = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
+
+                    if value_1 < value_2 {
+                        frame.instruction_pointer -= offset as u32;
+                        frame.instruction_pointer = if branch_offset < 0 { frame.instruction_pointer - branch_offset.abs() as u32} else { frame.instruction_pointer + branch_offset.abs() as u32};
+                    }
+                }
+
                 Instruction::BranchNonNull(branch_offset) => {
                     let test_value = wrap_stackframe_error(class, method, frame.operand_stack.pop_reference(0))?;
 
@@ -785,10 +803,10 @@ impl JVM {
                     }
                 }
 
-                Instruction::BranchZero(branch_offset) => {
+                Instruction::BranchPositive(branch_offset) => {
                     let test_value = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
 
-                    if test_value == 0 {
+                    if test_value > 0 {
                         frame.instruction_pointer -= offset as u32;
                         frame.instruction_pointer = if branch_offset < 0 { frame.instruction_pointer - branch_offset.abs() as u32} else { frame.instruction_pointer + branch_offset.abs() as u32};
                     }
@@ -804,6 +822,15 @@ impl JVM {
                     }
                 }
 
+                Instruction::BranchZero(branch_offset) => {
+                    let test_value = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
+
+                    if test_value == 0 {
+                        frame.instruction_pointer -= offset as u32;
+                        frame.instruction_pointer = if branch_offset < 0 { frame.instruction_pointer - branch_offset.abs() as u32} else { frame.instruction_pointer + branch_offset.abs() as u32};
+                    }
+                }
+
                 Instruction::CheckCast(classref_index) => {
                     // TODO: Class loading checks
                     let class_name = class.gather_class(classref_index)?;
@@ -1110,10 +1137,7 @@ impl JVM {
 
                     // TODO: Throw error
                     if ! self.class_store.are_types_compatible(&this_object_descriptor, &base_object_descriptor) {
-                        return Err(Error::RunTimeError(format!(
+                        return Err(Error::RunTimeError(format!("InvokeVirtual: Cannot call '{base_method_name}' from class '{base_class_name}' on instance from class '{this_object_class_name}: Types are incompatible'")))
-                                    "InvokeVirtual: Cannot call '{base_method_name}' from class '{base_class_name}' on instance from class '{}: Types are incompatible'", 
-                                    this_object_class_name  
-                                    )))
                     }
 
                     let (invoked_class_index, invoked_method_index, _invoked_method_info) = match ClassMethodIterator::new(this_object_class_index, &self.class_store)
@@ -1145,9 +1169,18 @@ impl JVM {
 
                 Instruction::LoadByteImmediate(byte) => {
                     // sign extend into int
-                    let i8_int = i8::from_be_bytes([byte]);
 
-                    let frame_result = frame.operand_stack.push(StackValue::Int(i8_int as i32));
+                    let frame_result = frame.operand_stack.push(StackValue::Int(byte as i32));
+                    match frame_result {
+                        Ok(_) => (),
+                        Err(err) => return Err(Error::StackFrameError(err, format!("in '{}', in class '{}'", method.name, class.get_classname().unwrap()))),
+                    }
+                }
+
+                Instruction::LoadShortImmediate(short) => {
+                    // sign extend into int
+
+                    let frame_result = frame.operand_stack.push(StackValue::Int(short as i32));
                     match frame_result {
                         Ok(_) => (),
                         Err(err) => return Err(Error::StackFrameError(err, format!("in '{}', in class '{}'", method.name, class.get_classname().unwrap()))),
@@ -1263,13 +1296,19 @@ impl JVM {
                             let string_obj_ref = self.heap_area.make_handmade_string(string_constant, &self.class_store);
 
                             wrap_stackframe_error(class, method, frame.operand_stack.push(StackValue::Reference(string_obj_ref)))?;
-                        },
+                        }
+
+                        ConstantPoolInfo::Integer(int_data) => {
+                            let int_value = int_data.value;
+
+                            wrap_stackframe_error(class, method, frame.operand_stack.push(StackValue::Int(int_value)))?;
+                        }
                         _ => {
                             println!("{:?}", class.pool_entry(wide_index).unwrap());
                             todo!()
                         }
                     }
-                },
+                }
 
                 Instruction::LoadLocalFloat0() => {
                     load_local_float(class, method, frame, 0)?;
@@ -1297,6 +1336,9 @@ impl JVM {
                     load_local_int(class, method, frame, 3)?;
                 }
 
+                Instruction::LoadLocalReference(index) => {
+                    load_local_reference(class, method, frame, index as usize)?;
+                }
                 Instruction::LoadLocalReference0() => {
                     load_local_reference(class, method, frame, 0)?;
                 }
@@ -1310,6 +1352,27 @@ impl JVM {
                     load_local_reference(class, method, frame, 3)?;
                 }
 
+                Instruction::LogicalShiftIntRight() => {
+                    let shift = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))? as u8 & 0b00011111;
+                    let int   = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
+                    let uint  = u32::from_ne_bytes(int.to_ne_bytes());
+                    let u_result = uint >> shift;
+                    let i_result = i32::from_ne_bytes(u_result.to_ne_bytes());
+
+                    wrap_stackframe_error(class, method, frame.operand_stack.push(StackValue::Int(i_result)))?;
+                }
+
+                Instruction::LookupSwitch(default_offset, pairs) => {
+                    let key = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
+                    let jump_offset = match pairs.binary_search_by(|(match_key, _offset)| match_key.cmp(&key)) {
+                        Ok(offset) => pairs[offset].1,
+                        Err(_) => default_offset,
+                    };
+
+                    frame.instruction_pointer -= offset as u32;
+                    frame.instruction_pointer = if jump_offset < 0 { frame.instruction_pointer - jump_offset.abs() as u32} else { frame.instruction_pointer + jump_offset.abs() as u32};
+                }
+
                 Instruction::MultiplyInt() => {
                     let factor_1 = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
                     let factor_2 = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
@@ -1519,17 +1582,23 @@ impl JVM {
                                 let value_native_name  = self.heap_area.object_area.get_reference_native_class_name(ref_value, &self.class_store);
                                 let parsed_native_name = AbstractTypeDescription::parse_first(value_native_name).unwrap().1;
 
-                                if ! self.class_store.are_types_compatible(&matched_field.descriptor, &parsed_native_name) {
+                                if ! self.class_store.are_types_compatible(&parsed_native_name, &matched_field.descriptor) {
                                     return Err(Error::RunTimeError(format!("PutStatic: Trying to set a value with type '{parsed_native_name:?}' on a field with type '{:?}'", matched_field.descriptor)));
                                 }
                             }
 
                             FieldValue::Reference(ref_value)
                         }
+
+                        (1..=255, _) => {
+                            let ref_value = wrap_stackframe_error(class, method, frame.operand_stack.pop_reference(0))?;
+                            FieldValue::Reference(ref_value)
+                        }
+
                         _ => {
                             println!("{:?}", matched_field);
                             todo!()
-                        },
+                        }
                     };
 
                     self.heap_area.static_area.set(target_class_name, target_field_name, set_value)?;
@@ -1568,13 +1637,6 @@ impl JVM {
                     return Ok(JVMCallbackOperation::PopFrame());
                 },
 
-                Instruction::ShiftIntRight() => {
-                    let shift = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))? as u8 & 0b00011111;
-                    let int   = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
-
-                    wrap_stackframe_error(class, method, frame.operand_stack.push(StackValue::Int(int >> shift)))?;
-                },
-
                 Instruction::StoreIntoBArray() => {
                     let value     = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
                     let index     = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
@@ -1582,7 +1644,7 @@ impl JVM {
 
                     match self.heap_area.object_area.get_entry(array_ref) {
                         CompartmentEntry::ByteArray(_) => {
-                            let byte_value = value.to_ne_bytes()[3];
+                            let byte_value = value as i8;
 
                             self.heap_area.object_area.set_array_element(array_ref, index as usize, FieldValue::Byte(byte_value));
                         }
@@ -1590,6 +1652,22 @@ impl JVM {
                     }
                 }
 
+                Instruction::StoreIntoCArray() => {
+                    let value     = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
+                    let index     = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
+                    let array_ref = wrap_stackframe_error(class, method, frame.operand_stack.pop_reference(0))?;
+
+                    match self.heap_area.object_area.get_entry(array_ref) {
+                        CompartmentEntry::CharArray(_) => {
+                            let int_bytes = value.to_ne_bytes();
+                            let char_value = u16::from_ne_bytes([int_bytes[2], int_bytes[3]]);
+
+                            self.heap_area.object_area.set_array_element(array_ref, index as usize, FieldValue::Char(char_value));
+                        }
+                        _ => todo!(), // TODO: Handle as error
+                    }
+                }
+
                 Instruction::StoreIntoRArray() => {
                     let value     = wrap_stackframe_error(class, method, frame.operand_stack.pop_reference(0))?;
                     let index     = wrap_stackframe_error(class, method, frame.operand_stack.pop_int(0))?;
@@ -1633,26 +1711,31 @@ impl JVM {
                     wrap_stackframe_error(class, method, frame.store_local(3, StackValue::Int(int)))?;
                 }
 
-                Instruction::StoreReference0() => {
+                Instruction::StoreLocalReference(index) => {
+                    let reference = wrap_stackframe_error(class, method, frame.operand_stack.pop_reference(0))?;
+
+                    wrap_stackframe_error(class, method, frame.store_local(index as u16, StackValue::Reference(reference)))?;
+                }
+                Instruction::StoreLocalReference0() => {
                     let reference = wrap_stackframe_error(class, method, frame.operand_stack.pop_reference(0))?;
 
                     wrap_stackframe_error(class, method, frame.store_local(0, StackValue::Reference(reference)))?;
-                },
+                }
-                Instruction::StoreReference1() => {
+                Instruction::StoreLocalReference1() => {
                     let reference = wrap_stackframe_error(class, method, frame.operand_stack.pop_reference(0))?;
 
                     wrap_stackframe_error(class, method, frame.store_local(1, StackValue::Reference(reference)))?;
-                },
+                }
-                Instruction::StoreReference2() => {
+                Instruction::StoreLocalReference2() => {
                     let reference = wrap_stackframe_error(class, method, frame.operand_stack.pop_reference(0))?;
 
                     wrap_stackframe_error(class, method, frame.store_local(2, StackValue::Reference(reference)))?;
-                },
+                }
-                Instruction::StoreReference3() => {
+                Instruction::StoreLocalReference3() => {
                     let reference = wrap_stackframe_error(class, method, frame.operand_stack.pop_reference(0))?;
 
                     wrap_stackframe_error(class, method, frame.store_local(3, StackValue::Reference(reference)))?;
-                },
+                }
 
                 _ => {
                     return Err(Error::RunTimeError(format!("Opcode not implemented yet: {:?}", instruction)))

src/native_methods.rs

@@ -290,6 +290,14 @@ impl JavaLangClass {
     }
 }
 
+struct JavaLangStringUTF16 {}
+
+impl JavaLangStringUTF16 {
+    pub fn is_big_endian(_jvm: &mut JVM) -> Result<JVMCallbackOperation, Error> {
+        Ok(JVMCallbackOperation::ReturnFrame(StackValue::Int(if cfg!(target_endian = "big") {1} else {0})))
+    }
+}
+
 struct JdkInternalMiscUnsafe {}
 
 impl JdkInternalMiscUnsafe {
@@ -357,8 +365,19 @@ impl JdkInternalUtilSystemPropsRaw {
         Ok(JVMCallbackOperation::ReturnFrame(StackValue::Reference(array_reference)))
     }
 
+    // command-line configured properties, should return at least java.home
     pub fn vm_properties(jvm: &mut JVM) -> Result<JVMCallbackOperation, Error> {
-        let array_reference = jvm.heap_area.make_empty_array(&jvm.class_store, AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Classname("java/lang/String".into()) }, 2);
+        let array_length = 4;
+        let array_reference = jvm.heap_area.make_empty_array(&jvm.class_store, AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Classname("java/lang/String".into()) }, array_length);
+
+        {
+            // TODO: Actual java home path
+            let java_home_key_reference   = jvm.heap_area.make_handmade_string(&String::from("java.home"), &jvm.class_store);
+            let java_home_value_reference = jvm.heap_area.make_handmade_string(&String::from("./"), &jvm.class_store);
+
+            jvm.heap_area.object_area.set_array_element(array_reference, 0, java_home_key_reference.into());
+            jvm.heap_area.object_area.set_array_element(array_reference, 1, java_home_value_reference.into());
+        }
 
         Ok(JVMCallbackOperation::ReturnFrame(StackValue::Reference(array_reference)))
     }
@@ -896,6 +915,20 @@ pub fn function_for(class_name: &str, m: &crate::classfile::MethodInfo) -> Resul
             Ok(todo_call)
         }
 
+        ("java/lang/StringUTF16", "isBigEndian") => {
+            // until JDK 23
+            let expected_descriptor = MethodDescriptor {
+                argument_types: Box::new([]),
+                return_type: AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Boolean() },
+            };
+
+            if m.descriptor != expected_descriptor {
+                return Err(Error::RunTimeError(format!("Native descriptor mismatch for method '{class_name}.{method_name}': found '{}' but expected '{}'", m.descriptor.source_string(), expected_descriptor.source_string())));
+            }
+
+            Ok(JavaLangStringUTF16::is_big_endian)
+        }
+
         ("java/lang/Object", "clone") => {
             let expected_descriptor = MethodDescriptor {
                 argument_types: Box::new([]),