start adding assignment (currently only identifier assignment works)

src/runtime/assignment/assignment.c

@@ -0,0 +1,30 @@
+/*
+ * SPDX-FileCopyrightText: 2025 William Bell
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "assignment.h"
+
+ArErr runtime_assignment(Translated *translated, RuntimeState *state,
+                         struct Stack *stack) {
+  int64_t length = pop_bytecode(translated, state);
+  int64_t offset = pop_bytecode(translated, state);
+  int64_t prehash = pop_bytecode(translated, state);
+  int64_t from_register = pop_byte(translated, state);
+  uint64_t hash =
+      runtime_hash(arena_get(&translated->constants, offset), length, prehash);
+  ArgonObject *key =
+      new_string_object(arena_get(&translated->constants, offset), length);
+  for (Stack *current_stack = stack; current_stack;
+       current_stack = current_stack->prev) {
+    ArgonObject *exists = hashmap_lookup_GC(current_stack->scope, hash);
+    if (exists) {
+      hashmap_insert_GC(current_stack->scope, hash, key,
+                        state->registers[from_register], 0);
+    }
+  }
+  hashmap_insert_GC(stack->scope, hash, key, state->registers[from_register],
+                    0);
+  return no_err;
+}