uInt8 TIA::peek()

in atari_py/ale_interface/src/emucore/TIA.cxx [1972:2130]

• 141 lines of code
• 49 McCabe index (conditional complexity)

uInt8 TIA::peek(uInt16 addr)
{
  // Update frame to current color clock before we look at anything!
  updateFrame(mySystem->cycles() * 3);

  uInt8 noise = mySystem->getDataBusState() & 0x3F;

  switch(addr & 0x000f)
  {
    case 0x00:    // CXM0P
      return ((myCollision & 0x0001) ? 0x80 : 0x00) | 
          ((myCollision & 0x0002) ? 0x40 : 0x00) | noise;

    case 0x01:    // CXM1P
      return ((myCollision & 0x0004) ? 0x80 : 0x00) | 
          ((myCollision & 0x0008) ? 0x40 : 0x00) | noise;

    case 0x02:    // CXP0FB
      return ((myCollision & 0x0010) ? 0x80 : 0x00) | 
          ((myCollision & 0x0020) ? 0x40 : 0x00) | noise;

    case 0x03:    // CXP1FB
      return ((myCollision & 0x0040) ? 0x80 : 0x00) | 
          ((myCollision & 0x0080) ? 0x40 : 0x00) | noise;

    case 0x04:    // CXM0FB
      return ((myCollision & 0x0100) ? 0x80 : 0x00) | 
          ((myCollision & 0x0200) ? 0x40 : 0x00) | noise;

    case 0x05:    // CXM1FB
      return ((myCollision & 0x0400) ? 0x80 : 0x00) | 
          ((myCollision & 0x0800) ? 0x40 : 0x00) | noise;

    case 0x06:    // CXBLPF
      return ((myCollision & 0x1000) ? 0x80 : 0x00) | noise;

    case 0x07:    // CXPPMM
      return ((myCollision & 0x2000) ? 0x80 : 0x00) | 
          ((myCollision & 0x4000) ? 0x40 : 0x00) | noise;

    case 0x08:    // INPT0
    {
      Int32 r = myConsole.controller(Controller::Left).read(Controller::Nine);
      if(r == Controller::minimumResistance)
      {
        return 0x80 | noise;
      }
      else if((r == Controller::maximumResistance) || myDumpEnabled)
      {
        return noise;
      }
      else
      {
        double t = (1.6 * r * 0.01E-6);
        uInt32 needed = (uInt32)(t * 1.19E6);
        if(mySystem->cycles() > (myDumpDisabledCycle + needed))
        {
          return 0x80 | noise;
        }
        else
        {
          return noise;
        }
      }
    }

    case 0x09:    // INPT1
    {
      Int32 r = myConsole.controller(Controller::Left).read(Controller::Five);
      if(r == Controller::minimumResistance)
      {
        return 0x80 | noise;
      }
      else if((r == Controller::maximumResistance) || myDumpEnabled)
      {
        return noise;
      }
      else
      {
        double t = (1.6 * r * 0.01E-6);
        uInt32 needed = (uInt32)(t * 1.19E6);
        if(mySystem->cycles() > (myDumpDisabledCycle + needed))
        {
          return 0x80 | noise;
        }
        else
        {
          return noise;
        }
      }
    }

    case 0x0A:    // INPT2
    {
      Int32 r = myConsole.controller(Controller::Right).read(Controller::Nine);
      if(r == Controller::minimumResistance)
      {
        return 0x80 | noise;
      }
      else if((r == Controller::maximumResistance) || myDumpEnabled)
      {
        return noise;
      }
      else
      {
        double t = (1.6 * r * 0.01E-6);
        uInt32 needed = (uInt32)(t * 1.19E6);
        if(mySystem->cycles() > (myDumpDisabledCycle + needed))
        {
          return 0x80 | noise;
        }
        else
        {
          return noise;
        }
      }
    }

    case 0x0B:    // INPT3
    {
      Int32 r = myConsole.controller(Controller::Right).read(Controller::Five);
      if(r == Controller::minimumResistance)
      {
        return 0x80 | noise;
      }
      else if((r == Controller::maximumResistance) || myDumpEnabled)
      {
        return noise;
      }
      else
      {
        double t = (1.6 * r * 0.01E-6);
        uInt32 needed = (uInt32)(t * 1.19E6);
        if(mySystem->cycles() > (myDumpDisabledCycle + needed))
        {
          return 0x80 | noise;
        }
        else
        {
          return noise;
        }
      }
    }

    case 0x0C:    // INPT4
      return myConsole.controller(Controller::Left).read(Controller::Six) ?
          (0x80 | noise) : noise;

    case 0x0D:    // INPT5
      return myConsole.controller(Controller::Right).read(Controller::Six) ?
          (0x80 | noise) : noise;

    case 0x0e:
      return noise;

    default:
      return noise;
  }
}