uInt8 CartridgeDPC::peek()

in atari_py/ale_interface/src/emucore/CartDPC.cxx [204:324]
90 lines of code
19 McCabe index (conditional complexity)

uInt8 CartridgeDPC::peek(uInt16 address)
{
  address = address & 0x0FFF;

  // Clock the random number generator.  This should be done for every
  // cartridge access, however, we're only doing it for the DPC and 
  // hot-spot accesses to save time.
  clockRandomNumberGenerator();

  if(address < 0x0040)
  {
    uInt8 result = 0;

    // Get the index of the data fetcher that's being accessed
    uInt32 index = address & 0x07;
    uInt32 function = (address >> 3) & 0x07;

    // Update flag register for selected data fetcher
    if((myCounters[index] & 0x00ff) == myTops[index])
    {
      myFlags[index] = 0xff;
    }
    else if((myCounters[index] & 0x00ff) == myBottoms[index])
    {
      myFlags[index] = 0x00;
    }

    switch(function)
    {
      case 0x00:
      {
        // Is this a random number read
        if(index < 4)
        {
          result = myRandomNumber;
        }
        // No, it's a music read
        else
        {
          static const uInt8 musicAmplitudes[8] = {
              0x00, 0x04, 0x05, 0x09, 0x06, 0x0a, 0x0b, 0x0f
          };

          // Update the music data fetchers (counter & flag)
          updateMusicModeDataFetchers();

          uInt8 i = 0;
          if(myMusicMode[0] && myFlags[5])
          {
            i |= 0x01;
          }
          if(myMusicMode[1] && myFlags[6])
          {
            i |= 0x02;
          }
          if(myMusicMode[2] && myFlags[7])
          {
            i |= 0x04;
          }

          result = musicAmplitudes[i];
        }
        break;
      }

      // DFx display data read
      case 0x01:
      {
        result = myDisplayImage[2047 - myCounters[index]];
        break;
      }

      // DFx display data read AND'd w/flag
      case 0x02:
      {
        result = myDisplayImage[2047 - myCounters[index]] & myFlags[index];
        break;
      } 

      // DFx flag
      case 0x07:
      {
        result = myFlags[index];
        break;
      }

      default:
      {
        result = 0;
      }
    }

    // Clock the selected data fetcher's counter if needed
    if((index < 5) || ((index >= 5) && (!myMusicMode[index - 5])))
    {
      myCounters[index] = (myCounters[index] - 1) & 0x07ff;
    }

    return result;
  }
  else
  {
    // Switch banks if necessary
    switch(address)
    {
      case 0x0FF8:
        // Set the current bank to the lower 4k bank
        bank(0);
        break;

      case 0x0FF9:
        // Set the current bank to the upper 4k bank
        bank(1);
        break;

      default:
        break;
    }
    return myProgramImage[myCurrentBank * 4096 + address];
  }
}