#pragma once

#include <assert.h>

#include "class_file.h"

struct frame {
  uint32_t * local_variable;
  uint32_t * operand_stack;
  uint16_t operand_stack_ix;
  #ifdef DEBUG
  uint32_t operand_stack_capacity;
  #endif
};

struct thread {
  uint32_t pc;
  struct class_file * current_class;
  struct method_info * current_method;
};

struct stack {
  union {
    struct frame * frame;
    uint32_t * data;
  };
  uint32_t ix;
  uint32_t capacity;
};

struct vm {
  struct stack frame_stack;
  struct stack data_stack;
  struct thread current_thread;
  struct frame * current_frame;
};

static inline void operand_stack_push_u32(struct frame * frame, uint32_t value)
{
  frame->operand_stack[frame->operand_stack_ix] = value;
  frame->operand_stack_ix++;
}

static inline uint32_t operand_stack_pop_u32(struct frame * frame)
{
  frame->operand_stack_ix--;
  uint32_t value = frame->operand_stack[frame->operand_stack_ix];
  frame->operand_stack[frame->operand_stack_ix] = -1;
  return value;
}

static inline void operand_stack_dup_u32(struct frame * frame)
{
  uint32_t value = frame->operand_stack[frame->operand_stack_ix - 1];
  frame->operand_stack[frame->operand_stack_ix] = value;
  frame->operand_stack_ix++;
}