void SuperFX::update_speed() {
  //force SuperFX1 mode?
  if(clockmode == 1) {
    cache_access_speed  = 2;
    memory_access_speed = 6;
    return;
  }

  //force SuperFX2 mode?
  if(clockmode == 2) {
    cache_access_speed  = 1;
    memory_access_speed = 5;
    //regs.cfgr.ms0 = 0;  //cannot use high-speed multiplication in 21MHz mode
    return;
  }

  //default: allow S-CPU to select mode
  cache_access_speed  = (regs.clsr ? 1 : 2);
  memory_access_speed = (regs.clsr ? 5 : 6);
  //if(regs.clsr) regs.cfgr.ms0 = 0;  //cannot use high-speed multiplication in 21MHz mode
}