class Memory{
  constructor(size, ro){
    this.__ro = (ro === true);
    this.__map = null;
    this.__addr = 0;
    if (size > 0){
      this.__map = new Uint8Array(size);
    }
  }

  get size(){return (this.__map) ? this.__map.length : 0;}

  get address(){return this.__addr;}
  set address(a){
    if (this.__map)
      this.__addr = Math.min(this.__map.length, Math.max(0, a));
  }

  get byte(){return (this.__map) ? this.__map[this.__addr] : -1;}
  set byte(b){
    if (!this.__ro && this.__map)
      this.__map[this.__addr] = b;
  }

  sysStore(address, data){
    if (this.__map){
      let dc = data;
      if (address < 0 || address >= this.__map.length)
        throw new RangeError("Memory address out of range.");
      if (this.__map.length - address < dc.length)
        dc = dc.slice(0, this.__map.length - address);
      this.__map.set(address, dc);
      return dc.length;
    }
  }
}


module.exports = Memory;