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

    Namco 54XX

    This custom chip is a Fujitsu MB8844 MCU programmed to act as a noise
    generator. It is used for explosions, the shoot sound in Bosconian,
    and the tire screech sound in Pole Position.

    CMD = command from main CPU
    OUTn = sound outputs (3 channels)

    The chip reads the command when the /IRQ is pulled down.

                       +------+
                     EX|1   28|Vcc
                      X|2   27|K3 (CMD7)
                 /RESET|3   26|K2 (CMD6)
            (OUT0.0) O0|4   25|K1 (CMD5)
            (OUT0.1) O1|5   24|K0 (CMD4)
            (OUT0.2) O2|6   23|R10/IRQ
            (OUT0.3) O3|7   22|R9/TC
            (OUT1.0) O4|8   21|R8
            (OUT1.1) O5|9   20|R7 (OUT2.3)
            (OUT1.2) O6|10  19|R6 (OUT2.2)
            (OUT1.3) O7|11  18|R5 (OUT2.1)
              (CMD0) R0|12  17|R4 (OUT2.0)
              (CMD1) R1|13  16|R3 (CMD3)
                    GND|14  15|R2 (CMD2)
                       +------+

    [1] The RNG that drives the type A output is output on pin 21, and
    the one that drives the type B output is output on pin 22, but those
    pins are not connected on the board.


    The command format is very simple:

    0x: nop
    1x: play sound type A
    2x: play sound type B
    3x: set parameters (type A) (followed by 4 bytes)
    4x: set parameters (type B) (followed by 4 bytes)
    5x: play sound type C
    6x: set parameters (type C) (followed by 5 bytes)
    7x: set volume for sound type C to x
    8x-Fx: nop

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

#include "driver.h"
#include "namco54.h"
#include "cpu/mb88xx/mb88xx.h"

typedef struct _namco_54xx_state namco_54xx_state;
struct _namco_54xx_state
{
	const device_config *cpu;
	const device_config *discrete;
	int basenode;
	UINT8 latched_cmd;
};

INLINE namco_54xx_state *get_safe_token(const device_config *device)
{
	assert(device != NULL);
	assert(device->token != NULL);
	assert(device->type == NAMCO_54XX);

	return (namco_54xx_state *)device->token;
}



static TIMER_CALLBACK( namco_54xx_latch_callback )
{
	namco_54xx_state *state = get_safe_token((const device_config *)ptr);
	state->latched_cmd = param;
}

static READ8_HANDLER( namco_54xx_K_r )
{
	namco_54xx_state *state = get_safe_token(space->cpu->owner);
	return state->latched_cmd >> 4;
}

static READ8_HANDLER( namco_54xx_R0_r )
{
	namco_54xx_state *state = get_safe_token(space->cpu->owner);
	return state->latched_cmd & 0x0f;
}


static WRITE8_HANDLER( namco_54xx_O_w )
{
	namco_54xx_state *state = get_safe_token(space->cpu->owner);
	UINT8 out = (data & 0x0f);
	if (data & 0x10)
		discrete_sound_w(state->discrete, NAMCO_54XX_1_DATA(state->basenode), out);
	else
		discrete_sound_w(state->discrete, NAMCO_54XX_0_DATA(state->basenode), out);
}

static WRITE8_HANDLER( namco_54xx_R1_w )
{
	namco_54xx_state *state = get_safe_token(space->cpu->owner);
	UINT8 out = (data & 0x0f);

	discrete_sound_w(state->discrete, NAMCO_54XX_2_DATA(state->basenode), out);
}




static TIMER_CALLBACK( namco_54xx_irq_clear )
{
	namco_54xx_state *state = get_safe_token((const device_config *)ptr);
	cpu_set_input_line(state->cpu, 0, CLEAR_LINE);
}

WRITE8_DEVICE_HANDLER( namco_54xx_write )
{
	namco_54xx_state *state = get_safe_token(device);

	timer_call_after_resynch(device->machine, (void *)device, data, namco_54xx_latch_callback);

	cpu_set_input_line(state->cpu, 0, ASSERT_LINE);

	// The execution time of one instruction is ~4us, so we must make sure to
	// give the cpu time to poll the /IRQ input before we clear it.
	// The input clock to the 06XX interface chip is 64H, that is
	// 18432000/6/64 = 48kHz, so it makes sense for the irq line to be
	// asserted for one clock cycle ~= 21us.
	timer_set(device->machine, ATTOTIME_IN_USEC(21), (void *)device, 0, namco_54xx_irq_clear);
}


/***************************************************************************
    DEVICE INTERFACE
***************************************************************************/

static ADDRESS_MAP_START( namco_54xx_map_io, ADDRESS_SPACE_IO, 8 )
	AM_RANGE(MB88_PORTK,  MB88_PORTK)  AM_READ(namco_54xx_K_r)
	AM_RANGE(MB88_PORTO,  MB88_PORTO)  AM_WRITE(namco_54xx_O_w)
	AM_RANGE(MB88_PORTR0, MB88_PORTR0) AM_READ(namco_54xx_R0_r)
	AM_RANGE(MB88_PORTR1, MB88_PORTR1) AM_WRITE(namco_54xx_R1_w)
	AM_RANGE(MB88_PORTR2, MB88_PORTR2) AM_NOP
ADDRESS_MAP_END


static MACHINE_DRIVER_START( namco_54xx )
	MDRV_CPU_ADD("mcu", MB8844, DERIVED_CLOCK(1,1))		/* parent clock, internally divided by 6 */
	MDRV_CPU_IO_MAP(namco_54xx_map_io)
MACHINE_DRIVER_END


ROM_START( namco_54xx )
	ROM_REGION( 0x400, "mcu", ROMREGION_LOADBYNAME )
	ROM_LOAD( "54xx.bin",     0x0000, 0x0400, CRC(ee7357e0) SHA1(01bdf984a49e8d0cc8761b2cc162fd6434d5afbe) )
ROM_END


/*-------------------------------------------------
    device start callback
-------------------------------------------------*/

static DEVICE_START( namco_54xx )
{
	namco_54xx_config *config = (namco_54xx_config *)device->inline_config;
	namco_54xx_state *state = get_safe_token(device);
	astring *tempstring = astring_alloc();

	/* find our CPU */
	state->cpu = cputag_get_cpu(device->machine, device_build_tag(tempstring, device, "mcu"));
	assert(state->cpu != NULL);
	astring_free(tempstring);

	/* find the attached discrete sound device */
	assert(config->discrete != NULL);
	state->discrete = devtag_get_device(device->machine, config->discrete);
	assert(state->discrete != NULL);
	state->basenode = config->firstnode;
}


/*-------------------------------------------------
    device definition
-------------------------------------------------*/

static const char DEVTEMPLATE_SOURCE[] = __FILE__;

#define DEVTEMPLATE_ID(p,s)		p##namco_54xx##s
#define DEVTEMPLATE_FEATURES	DT_HAS_START | DT_HAS_ROM_REGION | DT_HAS_MACHINE_CONFIG | DT_HAS_INLINE_CONFIG
#define DEVTEMPLATE_NAME		"Namco 54xx"
#define DEVTEMPLATE_FAMILY		"Namco I/O"
#include "devtempl.h"
