Refactor: Restructure project package hierarchy and add initial implementation for assembler instructions, shell commands, and exception handling.

src/jvmMain/kotlin/mtmc/asm/instructions/Instruction.kt

@@ -0,0 +1,72 @@
+package mtmc.asm.instructions
+
+import mtmc.asm.ASMElement
+import mtmc.asm.Assembler
+import mtmc.asm.instructions.ALUInstruction.Companion.disassemble
+import mtmc.emulator.MonTanaMiniComputer.Companion.isDoubleWordInstruction
+import mtmc.tokenizer.MTMCToken
+
+abstract class Instruction(
+  @JvmField val type: InstructionType,
+  labels: List<MTMCToken>,
+  @JvmField val instructionToken: MTMCToken
+) : ASMElement(labels, instructionToken.line) {
+  open fun validateLabel(assembler: Assembler) {
+    // default does nothing
+  }
+
+  override fun addError(error: String) {
+    addError(instructionToken, error)
+  }
+
+  abstract fun genCode(output: ByteArray, assembler: Assembler)
+
+  override var sizeInBytes: Int = type.sizeInBytes
+    get() = type.sizeInBytes
+
+  companion object {
+    @JvmStatic
+    fun isInstruction(cmd: String): Boolean {
+      return InstructionType.fromString(cmd) != null
+    }
+
+    fun disassemble(instruction: Short, previousInstruction: Short): String {
+      if (isDoubleWordInstruction(previousInstruction)) {
+        return instruction.toInt().toString()
+      }
+      val misc = MiscInstruction.disassemble(instruction)
+      if (misc != null) {
+        return misc
+      }
+      val aluOp = disassemble(instruction)
+      if (aluOp != null) {
+        return aluOp
+      }
+      val stack = StackInstruction.disassemble(instruction)
+      if (stack != null) {
+        return stack
+      }
+      val test = TestInstruction.disassemble(instruction)
+      if (test != null) {
+        return test
+      }
+      val lsr = LoadStoreRegisterInstruction.disassemble(instruction)
+      if (lsr != null) {
+        return lsr
+      }
+      val ls = LoadStoreInstruction.disassemble(instruction)
+      if (ls != null) {
+        return ls
+      }
+      val jumpReg = JumpInstruction.disassemble(instruction)
+      if (jumpReg != null) {
+        return jumpReg
+      }
+      val jump = JumpInstruction.disassemble(instruction)
+      if (jump != null) {
+        return jump
+      }
+      return "<unknown>"
+    }
+  }
+}