/*

    Parker Bros Merlin handheld computer game

*/

#include "emu.h"
#include "cpu/tms0980/tms0980.h"
#include "sound/speaker.h"

/* Layout */
#include "merlin.lh"


class merlin_state : public driver_device
{
public:
	merlin_state(const machine_config &mconfig, device_type type, const char *tag)
		: driver_device(mconfig, type, tag),
			m_speaker(*this, "speaker") ,
		m_maincpu(*this, "maincpu") { }

	virtual void machine_start();

	required_device<speaker_sound_device> m_speaker;

	DECLARE_READ8_MEMBER(read_k);
	DECLARE_WRITE16_MEMBER(write_o);
	DECLARE_WRITE16_MEMBER(write_r);

protected:
	UINT16  m_o;
	UINT16  m_r;
	required_device<cpu_device> m_maincpu;
};


#define LOG 0


static INPUT_PORTS_START( merlin )
	PORT_START("O0")
	PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_BUTTON1) PORT_CODE(KEYCODE_0)     PORT_NAME("R0")  // R0
	PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_BUTTON2) PORT_CODE(KEYCODE_1)     PORT_NAME("R1")  // R1
	PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_BUTTON4) PORT_CODE(KEYCODE_3)     PORT_NAME("R3")  // R3
	PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_BUTTON3) PORT_CODE(KEYCODE_2)     PORT_NAME("R2")  // R2

	PORT_START("O1")
	PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_BUTTON5) PORT_CODE(KEYCODE_4)     PORT_NAME("R4")  // R4
	PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_BUTTON6) PORT_CODE(KEYCODE_5)     PORT_NAME("R5")  // R5
	PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_BUTTON8) PORT_CODE(KEYCODE_7)     PORT_NAME("R7")  // R7
	PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_BUTTON7) PORT_CODE(KEYCODE_6)     PORT_NAME("R6")  // R6

	PORT_START("O2")
	PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_BUTTON9) PORT_CODE(KEYCODE_8)     PORT_NAME("R8")  // R8
	PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_BUTTON10) PORT_CODE(KEYCODE_9)     PORT_NAME("R9")  // R9
	PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_BUTTON13) PORT_CODE(KEYCODE_S)     PORT_NAME("Same Game")  // SG - same game
	PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_BUTTON11) PORT_CODE(KEYCODE_MINUS) PORT_NAME("R10")  // R10

	PORT_START("O3")
	PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_UNUSED)
	PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_BUTTON15) PORT_CODE(KEYCODE_C)     PORT_NAME("Comp Turn")  // Comp Turn
	PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_BUTTON14) PORT_CODE(KEYCODE_H)     PORT_NAME("Hit Me")  // Hit me
	PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_BUTTON12) PORT_CODE(KEYCODE_N)     PORT_NAME("New Game")  // NG - new game

INPUT_PORTS_END


/*
The keypad is a 4*4 matrix, connected like so:

       +----+  +----+  +----+  +----+
O0 o---| R0 |--| R1 |--| R2 |--| R3 |
       +----+  +----+  +----+  +----+
          |       |       |       |
       +----+  +----+  +----+  +----+
O1 o---| R4 |--| R5 |--| R6 |--| R7 |
       +----+  +----+  +----+  +----+
          |       |       |       |
       +----+  +----+  +----+  +----+
O2 o---| R8 |--| R9 |--|R10 |--| SG |
       +----+  +----+  +----+  +----+
          |       |       |       |
          |    +----+  +----+  +----+
O3 o------+----| CT |--| NG |--| HM |
          |    +----+  +----+  +----+
          |       |       |       |
          o       o       o       o
         K1      K2      K8      K4

SG = same game, CT = comp turn, NG = new game, HM = hit me
*/

READ8_MEMBER(merlin_state::read_k)
{
	UINT8 data = 0;

	if (LOG)
		logerror( "read_k\n" );

	if ( m_o & 0x01 )
	{
		data |= ioport("O0")->read();
	}

	if ( m_o & 0x02 )
	{
		data |= ioport("O1")->read();
	}

	if ( m_o & 0x04 )
	{
		data |= ioport("O2")->read();
	}

	if ( m_o & 0x08 )
	{
		data |= ioport("O3")->read();
	}

	return data;
}


/*
The speaker is connected to O4 through O6.  The 3 outputs are paralleled for
increased current driving capability.  They are passed thru a 220 ohm resistor
and then to the speaker, which has the other side grounded.  The software then
toggles these lines to make sounds and noises. (There is no audio generator
other than toggling it with a software delay between to make tones).
*/

WRITE16_MEMBER(merlin_state::write_o)
{
	if (LOG)
		logerror( "write_o: write %02x\n", data );

	m_o = data;

	m_speaker->level_w(m_o & 0x70);
}


/*

  LEDs:

      R0
 R1   R2   R3
 R4   R5   R6
 R7   R8   R9
      R10

When that particular R output is high, that LED is on.
*/

WRITE16_MEMBER(merlin_state::write_r)
{
	if (LOG)
		logerror( "write_r: write %04x\n", data );

	m_r = data;

	output_set_value( "led_0",  BIT( m_r,  0 ) );
	output_set_value( "led_1",  BIT( m_r,  1 ) );
	output_set_value( "led_2",  BIT( m_r,  2 ) );
	output_set_value( "led_3",  BIT( m_r,  3 ) );
	output_set_value( "led_4",  BIT( m_r,  4 ) );
	output_set_value( "led_5",  BIT( m_r,  5 ) );
	output_set_value( "led_6",  BIT( m_r,  6 ) );
	output_set_value( "led_7",  BIT( m_r,  7 ) );
	output_set_value( "led_8",  BIT( m_r,  8 ) );
	output_set_value( "led_9",  BIT( m_r,  9 ) );
	output_set_value( "led_10", BIT( m_r, 10 ) );
}


void merlin_state::machine_start()
{
	save_item(NAME(m_o));
	save_item(NAME(m_r));
}


static const UINT16 merlin_output_pla[0x20] =
{
	/* O output PLA configuration currently unknown */
	0x01, 0x10, 0x30, 0x70, 0x02, 0x12, 0x32, 0x72,
	0x04, 0x14, 0x34, 0x74, 0x08, 0x18, 0x38, 0x78,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};


static MACHINE_CONFIG_START( merlin, merlin_state )
	MCFG_CPU_ADD( "maincpu", TMS1100, 500000 )  /* Clock may be wrong */
	MCFG_TMS1XXX_OUTPUT_PLA( merlin_output_pla )
	MCFG_TMS1XXX_READ_K( READ8( merlin_state, read_k ) )
	MCFG_TMS1XXX_WRITE_O( WRITE16( merlin_state, write_o ) )
	MCFG_TMS1XXX_WRITE_R( WRITE16( merlin_state, write_r ) )

	MCFG_DEFAULT_LAYOUT(layout_merlin)

	MCFG_SPEAKER_STANDARD_MONO("mono")
	MCFG_SOUND_ADD("speaker", SPEAKER_SOUND, 0)
	MCFG_SOUND_ROUTE(ALL_OUTPUTS, "mono", 0.25)
MACHINE_CONFIG_END


ROM_START( merlin )
	ROM_REGION( 0x800, "maincpu", 0 )
	// This rom needs verification, that's why it is marked as a bad dump
	// We had to change one byte in the original dump at offset 0x096 from
	// 0x5E to 0x1E to make 'Music Machine' working.
	// The hashes below are from the manually changed dump
	ROM_LOAD( "mp3404", 0x0000, 0x800, BAD_DUMP CRC(7515a75d) SHA1(76ca3605d3fde1df62f79b9bb1f534c2a2ae0229) )
ROM_END

/***************************************************************************

  Game driver(s)

***************************************************************************/

/*    YEAR  NAME        PARENT  COMPAT  MACHINE     INPUT   INIT    COMPANY            FULLNAME      FLAGS */
CONS( 1978, merlin,     0,      0,      merlin,     merlin, driver_device,  0,      "Parker Brothers", "Merlin", 0 )
