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

	microbee.c

    machine driver
	Juergen Buchmueller <pullmoll@t-online.de>, Jan 2000

	"busnop" emulation by R. Belmont, May 2006.

	"busnop" is a trick by which all reads from 0x0000-0x7FFF are held at 0x00
	until A15 is asserted.  The Z80 NOP instruction is 0x00, so the effect is
	to cause reset to skip all memory up to 0x8000, where the actual handling
	code resides.
	
****************************************************************************/

#include "driver.h"
#include "machine/z80ctc.h"
#include "machine/z80pio.h"
#include "machine/z80sio.h"
#include "video/generic.h"
#include "machine/wd17xx.h"
#include "includes/mbee.h"
#include "devices/cassette.h"
#include "cpu/z80/z80.h"
#include "sound/speaker.h"
#include "image.h"

static UINT8 fdc_drv = 0;
static UINT8 fdc_head = 0;
static UINT8 fdc_den = 0;
static UINT8 fdc_status = 0;
static void pio_interrupt(int state);
static void mbee_fdc_callback(wd17xx_state_t event, void *param);
static UINT8 mbee_busnop = 0;

UINT8 *mbee_workram;

static z80pio_interface pio_intf =
{
	pio_interrupt,	/* callback when change interrupt status */
	0,				/* portA ready active callback (do not support yet)*/
	0				/* portB ready active callback (do not support yet)*/
};

static void pio_interrupt(int state)
{
	cpunum_set_input_line(0, 0, state ? ASSERT_LINE : CLEAR_LINE);
}

/*
  NOTE: the original hardware has a "busnop" circuit which is enabled on reset/poweron.
  It causes all reads to return 0x00 until A15 is asserted (e.g. a read at or above 0x8000).
  The following stuff emulates that functionality.
*/

READ8_HANDLER( mbee_lowram_r )
{
	if (mbee_busnop)
	{
		return 0;
	}

	return mbee_workram[offset];
}

offs_t mbee_opbase_handler(offs_t address)
{
	if (address > 0x7fff)
	{
		mbee_busnop = 0;
	}

	return address;
}

offs_t mbee56_opbase_handler(offs_t address)
{
	if (address > 0xdfff)
	{
		mbee_busnop = 0;
	}

	return address;
}

MACHINE_RESET( mbee )
{
	mbee_busnop = 1;
}

static void mbee_machine_start(opbase_handler handler)
{
	z80pio_init(0, &pio_intf);
	wd17xx_init(WD_TYPE_179X,mbee_fdc_callback, NULL);
	memory_set_opbase_handler(0, handler);
}

MACHINE_START( mbee )
{
	mbee_machine_start(mbee_opbase_handler);
}

MACHINE_START( mbee56 )
{
	mbee_machine_start(mbee56_opbase_handler);
}

static mess_image *cassette_device_image(void)
{
	return image_from_devtype_and_index(IO_CASSETTE, 0);
}

/* PIO B data bits
 * 0	cassette data (input)
 * 1	cassette data (output)
 * 2	rs232 clock or DTR line
 * 3	rs232 CTS line (0: clear to send)
 * 4	rs232 input (0: mark)
 * 5	rs232 output (1: mark)
 * 6	speaker
 * 7	network interrupt
 */
READ8_HANDLER ( mbee_pio_r )
{
    UINT8 data = (offset & 2) ? z80pio_c_r(0, offset & 1) : z80pio_d_r(0, offset & 1);
	if( offset != 2 )
		return data;

    data |= 0x01;
	if (cassette_input(cassette_device_image()) > 0.03)
		data &= ~0x01;

    return data;
}

WRITE8_HANDLER ( mbee_pio_w )
{
	if (offset & 2)
		z80pio_c_w(0, offset & 1, data);
	else
		z80pio_d_w(0, offset & 1, data);

	if( offset == 2 )
	{
		cassette_output(cassette_device_image(), (data & 0x02) ? -1.0 : +1.0);
		speaker_level_w(0, (data >> 6) & 1);
	}
}

static void mbee_fdc_callback(wd17xx_state_t state, void *param)
{
	switch( state )
	{
	case WD17XX_IRQ_CLR:
//		cpunum_set_input_line(0,0,CLEAR_LINE);
		fdc_status &= ~0x40;
        break;
	case WD17XX_IRQ_SET:
//		cpunum_set_input_line(0,0,HOLD_LINE);
		fdc_status |= 0x40;
        break;
	case WD17XX_DRQ_CLR:
		fdc_status &= ~0x80;
		break;
	case WD17XX_DRQ_SET:
		fdc_status |= 0x80;
        break;
    }
}

 READ8_HANDLER ( mbee_fdc_status_r )
{
	logerror("mbee fdc_motor_r $%02X\n", fdc_status);
	return fdc_status;
}

WRITE8_HANDLER ( mbee_fdc_motor_w )
{
	logerror("mbee fdc_motor_w $%02X\n", data);
	/* Controller latch bits
	 * 0-1	driver select
	 * 2	head select
	 * 3	density (0: FM, 1:MFM)
	 * 4-7	unused
	 */
	fdc_drv = data & 3;
	fdc_head = (data >> 2) & 1;
	fdc_den = (data >> 3) & 1;
	wd17xx_set_drive(fdc_drv);
	wd17xx_set_side(fdc_head);
	if (data & (1<<3))
	{
	   wd17xx_set_density(DEN_FM_HI);
	}
	else
	{
	   wd17xx_set_density(DEN_MFM_LO);
	}

}

void mbee_interrupt(void)
{
    /* once per frame, pulse the PIO B bit 7 */
    logerror("mbee interrupt\n");
	z80pio_p_w(0, 1, 0x80);
    z80pio_p_w(0, 1, 0x00);
}

DEVICE_LOAD( mbee_cart )
{
	int size = image_length(image);
	UINT8 *mem = malloc(size);
	if( mem )
	{
		if( image_fread(image, mem, size) == size )
		{
			memcpy(memory_region(REGION_CPU1)+0x8000, mem, size);
		}
		free(mem);
	}
	return INIT_PASS;
}
