text: // license:BSD-3-Clause
  // copyright-holders:AJR
  /******************************************************************************
  
      Video System C7-01 GGA (Graphics Gate Array?)
  
      Skeleton device.
  
  ******************************************************************************/
  
  #include "emu.h"
  #include "vsystem_gga.h"
  
  
  //**************************************************************************
  //  VIDEO SYSTEM GGA DEVICE
  //**************************************************************************
  
  // device type definition
  DEFINE_DEVICE_TYPE(VSYSTEM_GGA, vsystem_gga_device, "vsystem_gga", "Video System C7-01 GGA")
  
  //-------------------------------------------------
  //  vsystem_gga_device - constructor
  //-------------------------------------------------
  
  vsystem_gga_device::vsystem_gga_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
  	: device_t(mconfig, VSYSTEM_GGA, tag, owner, clock),
  		device_video_interface(mconfig, *this, false),
  		m_write_cb(*this)
  {
  }
  
  //-------------------------------------------------
  //  device_start - device-specific startup
  //-------------------------------------------------
  
  void vsystem_gga_device::device_start()
  {
  	m_write_cb.resolve();
  
  	m_address_latch = 0;
  	for (u8 &reg : m_regs)
  		reg = 0;
  
  	save_item(NAME(m_address_latch));
  	save_item(NAME(m_regs));
  }
  
  //-------------------------------------------------
  //  write - register write handler
  //-------------------------------------------------
  
  WRITE8_MEMBER(vsystem_gga_device::write)
  {
  	if (offset & 1)
  	{
  		// address write
  		m_address_latch = data & 0x0f;
  	}
  	else
  	{
  		// data write
  		m_regs[m_address_latch] = data;
  		if (m_write_cb.isnull())
  			logerror("Setting register $%02x = %02x\n", m_address_latch, data);
  		else
  			m_write_cb(m_address_latch, data, 0xff);
  	}
  }
  