#ifndef VM_H
#define VM_H

#define STACK_MAX 1024
#define GC_THRESHOLD 256

// Primitive types for garbage collection
enum garbageData {
  GARBAGE_INT,
  GARBAGE_PAIR,
};

// Holds type and value data for the virtual machine
struct garbageObject {
  enum garbageData type;
  struct garbageObject *next;
  unsigned char mark;

  union {
    int value;

    struct {
      struct garbageObject *head;
      struct garbageObject *tail;
    };
  };
};

// Virtual machine hold the stack to trace references
struct virtualMachine {
  int stackSize;
  unsigned refCount;
  unsigned refMax;
  struct garbageObject *head;
  struct garbageObject *stack[STACK_MAX];
};

// Create a new garbageObject
struct garbageObject *initGarbage(struct virtualMachine *vm,
                                  enum garbageData type);

// Create a new VM
struct virtualMachine *initVM(void);

void deinitVM(struct virtualMachine *vm);

// Generic function to push data onto the VM stack
void push(struct virtualMachine *vm, struct garbageObject *value);

// Pop data from the VM stack
struct garbageObject *pop(struct virtualMachine *vm);

// Push a GARBAGE_INT onto the VM stack
void pushInt(struct virtualMachine *vm, int value);

// Push a GARBAGE_PAIR onto the VM stack
struct garbageObject *pushPair(struct virtualMachine *vm);

#endif /* VM_H */