Added tons of opcode documentation, changed license to ISC and a lot of file refactoring.

src/vm/core/swap.c

@@ -1,3 +1,30 @@
+/**
+ * This file is part of the Fun programming language.
+ * https://hanez.org/project/fun/
+ *
+ * Copyright 2025 Johannes Findeisen <you@hanez.org>
+ * Licensed under the terms of the ISC license.
+ * https://opensource.org/license/isc-license-txt
+ */
+
+/**
+* @file swap.c
+ * @brief Implements the OP_SWAP opcode for stack manipulation in the VM.
+ *
+ * This file handles the OP_SWAP instruction, which swaps the top two values
+ * on the stack.
+ *
+ * Behavior:
+ * - Swaps stack[sp] and stack[sp-1]
+ * - No type checking
+ *
+ * Error Handling:
+ * - Exits if stack underflow
+ *
+ * @author Johannes Findeisen
+ * @date 2025-10-16
+ */
+
 case OP_SWAP: {
     if (vm->sp < 1) {
         fprintf(stderr, "Runtime error: stack underflow for SWAP\n");