content: package com.grapeshot.halfnes.mappers;
  
  import com.grapeshot.halfnes.*;
  
  public class Mapper231 extends Mapper {
  
      @Override
      public void loadrom() throws BadMapperException {
          //needs to be in every mapper. Fill with initial cfg
          super.loadrom();
          for (int i = 0; i < 32; ++i) {
              prg_map[i] = (1024 * i) & (prgsize - 1);
          }
          for (int i = 0; i < 8; ++i) {
              chr_map[i] = (1024 * i) & (chrsize - 1);
          }
      }
  
      @Override
      public final void cartWrite(final int addr, final int data) {
          if (addr < 0x8000 || addr > 0xffff) {
              super.cartWrite(addr, data);
              return;
          }
  
          setmirroring(((addr & (utils.BIT7)) != 0) ? MirrorType.H_MIRROR : MirrorType.V_MIRROR);
  
          int prg = addr & 0x1E;
  
          //remap PRG bank
          for (int i = 0; i < 16; ++i) {
              prg_map[i] = (1024 * (i + 16 * prg)) & (prgsize - 1);
          }
          for (int i = 0; i < 16; ++i) {
              prg_map[i + 16] = (1024 * (i + 16 * (prg | (addr >> 5 & 1)))) & (prgsize - 1);
          }
      }
  }
  