#include "vm.h"
#include "lib/commons.h"

void vm_init(vm_t* vm)
{
  assert(vm);

  vm->pc = 0;
  vm->bp = 0;
  vm->sp = 0;
}

void vm_free(vm_t* vm)
{
  assert(vm);
}

size_t vm_stack_str(vm_t* vm, char* buffer, size_t size)
{
  assert(vm);
  assert(buffer);

  size_t sz = 0;

  for (size_t i=0; i<vm->sp; i++)
    {
      sz += snprintf(buffer + sz, size - sz, "| %d |\n", vm->stack[vm->sp - 1 - i]);
    }

  return sz;
}

void vm_exec_mod(vm_t* vm, mod_t* mod)
{
  assert(vm);
  vm->pc = 0;

  while (vm->pc < mod->program.size)
    {
      vm_exec_instr(vm, mod->program.ops[vm->pc],
                    mod->program.params[vm->pc]);
    }
}

void vm_exec_instr(vm_t* vm, Opcode op, param_t param)
{
  assert(vm);

  switch (op)
    {

    case OP_PUSH: {
      if (vm->sp + 1 >= RZ_STACK_LIMIT)
        {
          fprintf(stderr, "Stack overflow\n");
          abort();
        }

      vm->stack[vm->sp] = param;
      vm->sp++;
      vm->pc++;
    } break;

    default: {
      fprintf(stderr, "Cannot execute unknown opcode '%s'.\n",
              OpcodeStr[op]);
      abort();
    };
    }
}