content: /*
   * HalfNES by Andrew Hoffman
   * Licensed under the GNU GPL Version 3. See LICENSE file
   */
  package com.grapeshot.halfnes.mappers;
  
  import com.grapeshot.halfnes.*;
  
  public class VRC1Mapper extends Mapper {
  
      int prgbank0, prgbank1, prgbank2 = 0;
      int[] chrbank = {0, 0};
  
      @Override
      public void loadrom() throws BadMapperException {
          // needs to be in every mapper. Fill with initial cfg
          super.loadrom();
          //swappable bank
          for (int i = 0; i < 24; ++i) {
              prg_map[i] = (1024 * i) & (prgsize - 1);
          }
          //fixed bank
          for (int i = 1; i <= 8; ++i) {
              prg_map[32 - i] = prgsize - (1024 * i);
          }
          for (int i = 0; i < 8; ++i) {
              chr_map[i] = (1024 * i) & (chrsize - 1);
          }
      }
  
      @Override
      public final void cartWrite(int addr, int data) {
          if (addr < 0x8000 || addr > 0xffff) {
              super.cartWrite(addr, data);
              return;
          }
  
          switch (addr >> 12) {
              case 0x8:
                  prgbank0 = data & 0xf;
                  setbanks();
                  break;
              case 0x9:
                  setmirroring(((data & (utils.BIT0)) != 0) ? MirrorType.H_MIRROR : MirrorType.V_MIRROR);
                  chrbank[0] = (chrbank[0] & 0xf) | ((data << 3) & 0x10);
                  chrbank[1] = (chrbank[1] & 0xf) | ((data << 2) & 0x10);
                  setbanks();
                  break;
              case 0xA:
                  prgbank1 = data & 0xf;
                  setbanks();
                  break;
              case 0xC:
                  prgbank2 = data & 0xf;
                  setbanks();
                  break;
              case 0xE:
                  chrbank[0] = (chrbank[0] & 0x10) | (data & 0xf);
                  setbanks();
                  break;
              case 0xF:
                  chrbank[1] = (chrbank[1] & 0x10) | (data & 0xf);
                  setbanks();
                  break;
          }
      }
  
      private void setbanks() {
          //map prg banks
          //last bank fixed to the last bank in ROM
          for (int i = 1; i <= 8; ++i) {
              prg_map[32 - i] = prgsize - (1024 * i);
          }
          //first bank set to prg0 register
          for (int i = 0; i < 8; ++i) {
              prg_map[i] = (1024 * (i + 8 * prgbank0)) % (prgsize - 1);
          }
          //second bank set to prg1 register
          for (int i = 0; i < 8; ++i) {
              prg_map[i + 8] = (1024 * (i + 8 * prgbank1)) % (prgsize - 1);
          }
          //third bank set to prg2 register
          for (int i = 0; i < 8; ++i) {
              prg_map[i + 16] = (1024 * (i + 8 * prgbank2)) % (prgsize - 1);
          }
  
          //map chr banks
          setppubank(4, 0, chrbank[0]);
          setppubank(4, 4, chrbank[1]);
      }
  
      private void setppubank(int banksize, int bankpos, int banknum) {
          for (int i = 0; i < banksize; ++i) {
              chr_map[i + bankpos] = (1024 * (i + 4 * banknum)) % (chrsize - 1);
          }
      }
  }
  