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

  machine.c

  Functions to emulate general aspects of the machine (RAM, ROM, interrupts,
  I/O ports)

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

#include "includes/trs80.h"
#include "devices/basicdsk.h"
#include "devices/flopdrv.h"
#include "sound/speaker.h"

#ifdef MAME_DEBUG
#define VERBOSE 1
#else
#define VERBOSE 0
#endif

#if VERBOSE
#define LOG(x)	logerror x
#else
#define LOG(x)
#endif


UINT8 trs80_port_ff = 0;

#define IRQ_TIMER		0x80
#define IRQ_FDC 		0x40
static	UINT8			irq_status = 0;

#define MAX_LUMPS		192 	/* crude storage units - don't now much about it */
#define MAX_GRANULES	8		/* lumps consisted of granules.. aha */
#define MAX_SECTORS 	5		/* and granules of sectors */

#ifdef USE_TRACK
static UINT8 track[4] = {0, };				/* current track per drive */
#endif
static UINT8 head;							 /* current head per drive */
#ifdef USE_SECTOR
static UINT8 sector[4] = {0, }; 			/* current sector per drive */
#endif
static UINT8 irq_mask = 0;

static UINT8 *cas_buff = NULL;
static UINT32 cas_size = 0;

/* current tape file handles */
static mame_file *tape_put_file = NULL;
static mame_file *tape_get_file = NULL;

/* tape buffer for the first eight bytes at write (to extract a filename) */
static UINT8 tape_buffer[8];

static int tape_count = 0;		/* file offset within tape file */
static int put_bit_count = 0;	/* number of sync and data bits that were written */
static int get_bit_count = 0;	/* number of sync and data bits to read */
static int tape_bits = 0;		/* sync and data bits mask */
static int tape_time = 0;		/* time in cycles for the next bit at read */
static int in_sync = 0; 		/* flag if writing to tape detected the sync header A5 already */
static int put_cycles = 0;		/* cycle count at last output port change */
static int get_cycles = 0;		/* cycle count at last input port read */

static void tape_put_byte(UINT8 value);
static void tape_get_open(void);
static void tape_put_close(running_machine *machine);

#define FW TRS80_FONT_W
#define FH TRS80_FONT_H


static TIMER_CALLBACK(cas_copy_callback)
{
	UINT16 entry = 0, block_ofs = 0, block_len = 0;
	unsigned offs = 0;

	while( cas_size > 3 )
	{
		UINT8 data = cas_buff[offs++];

		switch( data )
		{
		case 0x3c:		   /* CAS file header */
			block_len = cas_buff[offs++];
			/* on CMD files size=zero means size 256 */
			if( block_len == 0 )
				block_len += 256;
			block_ofs = cas_buff[offs++];
			block_ofs += 256 * cas_buff[offs++];
			cas_size -= 4;
			LOG(("cas_copy_callback block ($%02X) %d at $%04X\n", data, block_len, block_ofs));
			while( block_len && cas_size )
			{
				program_write_byte_8(block_ofs, cas_buff[offs]);
				offs++;
				block_ofs++;
				block_len--;
				cas_size--;
			}
			/* skip the CHKSUM byte */
			offs++;
			break;
		case 0x78:
			entry = cas_buff[offs++];
			entry += 256 * cas_buff[offs++];
			LOG(("cas_copy_callback entry ($%02X) at $%04X\n", data, entry));
			cas_size -= 3;
			break;
		default:
			cas_size--;
		}
	}
	cas_size = 0;
	activecpu_set_reg(Z80_PC, entry);
}

DEVICE_LOAD( trs80_cas )
{
	cas_size = image_length(image);
	cas_buff = image_ptr(image);
	if (!cas_buff)
		return INIT_FAIL;

	if (cas_buff[1] == 0x55)
	{
		LOG(("trs80_cas_init: loading %s size %d\n", image_filename(image), cas_size));
	}
	else
	{
		cas_buff = NULL;
		cas_size = 0;
		logerror("trs80_cas_init: CAS file is not in SYSTEM format\n");
		return 1;
	}
	return 0;
}

DEVICE_UNLOAD( trs80_cas )
{
	cas_buff = NULL;
	cas_size = 0;
}

extern QUICKLOAD_LOAD( trs80_cmd )
{
	UINT16 entry = 0, block_ofs = 0, block_len = 0;
	unsigned offs = 0;
	UINT8 *cmd_buff;

	cmd_buff = malloc(quickload_size);
	if (!cmd_buff)
		return INIT_FAIL;

	while( quickload_size > 3 )
	{
		UINT8 data = cmd_buff[offs++];

		switch( data ) {
		case 0x01:		   /* CMD file header */
		case 0x07:		   /* another type of CMD file header */
			block_len = cmd_buff[offs++];
			/* on CMD files size=zero means size 256 */
			if( block_len == 0 )
				block_len += 256;
			block_ofs = cmd_buff[offs++];
			block_ofs += 256 * cmd_buff[offs++];
			block_len -= 2;
			if( block_len == 0 )
				block_len = 256;
			quickload_size -= 4;
			LOG(("trs80_cmd_load block ($%02X) %d at $%04X\n", data, block_len, block_ofs));
			while( block_len && quickload_size )
			{
				program_write_byte_8(block_ofs, cmd_buff[offs]);
				offs++;
				block_ofs++;
				block_len--;
				quickload_size--;
			}
			break;
		case 0x02:
			block_len = cmd_buff[offs++];
			quickload_size -= 1;
			if (entry == 0)
			{
				entry = cmd_buff[offs++];
				entry += 256 * cmd_buff[offs++];
				LOG(("trs80_cmd_load entry ($%02X) at $%04X\n", data, entry));
			}
			else
			{
				UINT16 temp;
				temp = cmd_buff[offs++];
				temp += 256 * cmd_buff[offs++];
				LOG(("trs80_cmd_load 2nd entry ($%02X) at $%04X ignored\n", data, temp));
			}
			quickload_size -= 3;
			break;
		default:
			quickload_size--;
		}
	}
	activecpu_set_reg(Z80_PC, entry);

	free(cmd_buff);
	return INIT_PASS;
}

DEVICE_LOAD( trs80_floppy )
{
	static UINT8 pdrive[4*16];
	int i;
	int tracks; 	/* total tracks count per drive */
	int heads;		/* total heads count per drive */
	int spt;		/* sector per track count per drive */
	int dir_sector; /* first directory sector (aka DDSL) */
	int dir_length; /* length of directory in sectors (aka DDGA) */
	int id = image_index_in_device(image);

    if (device_load_basicdsk_floppy(image) != INIT_PASS)
		return INIT_FAIL;

    if (image_index_in_device(image) == 0)        /* first floppy? */
	{
		image_fseek(image, 0, SEEK_SET);
		image_fread(image, pdrive, 2);
#if 0
		if (pdrive[0] != 0x00 || pdrive[1] != 0xfe)
		{
			basicdsk_read_sectormap(image, &tracks[id], &heads[id], &spt[id]);
		}
		else
#endif

		image_fseek(image, 2 * 256, SEEK_SET);
		image_fread(image, pdrive, 4*16);
	}

	tracks = pdrive[id*16+3] + 1;
	heads = (pdrive[id*16+7] & 0x40) ? 2 : 1;
	spt = pdrive[id*16+4] / heads;
	dir_sector = 5 * pdrive[id*16+0] * pdrive[id*16+5];
	dir_length = 5 * pdrive[id*16+9];

    /* set geometry so disk image can be read */
	basicdsk_set_geometry(image, tracks, heads, spt, 256, 0, 0, FALSE);

	/* mark directory sectors with deleted data address mark */
	/* assumption dir_sector is a sector offset */
	for (i = 0; i < dir_length; i++)
	{
		int track, side, sector_id;
		int track_offset, sector_offset;

		/* calc sector offset */
		sector_offset = dir_sector + i;

		/* get track offset */
		track_offset = sector_offset / spt;

		/* calc track */
		track = track_offset / heads;

		/* calc side */
		side = track_offset % heads;

		/* calc sector id - first sector id is 0! */
		sector_id = sector_offset % spt;

		/* set deleted data address mark for sector specified */
		basicdsk_set_ddam(image, track, side, sector_id, 1);
	}
    return INIT_PASS;
}

static void trs80_fdc_callback(wd17xx_state_t event, void *param);

static void trs80_machine_reset(running_machine *machine)
{
	if (cas_size)
	{
		LOG(("trs80_init_machine: schedule cas_copy_callback (%d)\n", cas_size));
		mame_timer_set(MAME_TIME_IN_MSEC(500), 0, cas_copy_callback);
	}
}

DRIVER_INIT( trs80 )
{
	UINT8 *FNT = memory_region(REGION_GFX1);
	int i, y;

	for( i = 0x000; i < 0x080; i++ )
	{
		/* copy eight lines from the character generator */
		for (y = 0; y < 8; y++)
			FNT[i*FH+y] = FNT[0x0800+i*8+y] << 3;
		/* wipe out the lower lines (no descenders!) */
		for (y = 8; y < FH; y++)
			FNT[i*FH+y] = 0;
	}
	/* setup the 2x3 chunky block graphics (two times 64 characters) */
	for( i = 0x080; i < 0x100; i++ )
	{
		UINT8 b0, b1, b2, b3, b4, b5;
		b0 = (i & 0x01) ? 0xe0 : 0x00;
		b1 = (i & 0x02) ? 0x1c : 0x00;
		b2 = (i & 0x04) ? 0xe0 : 0x00;
		b3 = (i & 0x08) ? 0x1c : 0x00;
		b4 = (i & 0x10) ? 0xe0 : 0x00;
		b5 = (i & 0x20) ? 0x1c : 0x00;

		FNT[i*FH+ 0] = FNT[i*FH+ 1] = FNT[i*FH+ 2] = FNT[i*FH+ 3] = b0 | b1;
		FNT[i*FH+ 4] = FNT[i*FH+ 5] = FNT[i*FH+ 6] = FNT[i*FH+ 7] = b2 | b3;
		FNT[i*FH+ 8] = FNT[i*FH+ 9] = FNT[i*FH+10] = FNT[i*FH+11] = b4 | b5;
	}
}

MACHINE_START( trs80 )
{
	wd17xx_init(WD_TYPE_179X,trs80_fdc_callback, NULL);
	add_reset_callback(machine, trs80_machine_reset);
	add_exit_callback(machine, tape_put_close);
}

/*************************************
 *
 *				Tape emulation.
 *
 *************************************/

static void tape_put_byte(UINT8 value)
{
	if (tape_count < 8)
	{
		tape_buffer[tape_count++] = value;
		if (tape_count == 8)
		{
			/* BASIC tape ? */
			if (tape_buffer[1] == 0xd3)
			{
				char filename[12+1];
				UINT8 zeroes[256] = {0,};

				sprintf(filename, "basic%c.cas", tape_buffer[4]);
				mame_fopen(SEARCHPATH_IMAGE, filename, OPEN_FLAG_READ | OPEN_FLAG_WRITE, &tape_put_file);
				mame_fwrite(tape_put_file, zeroes, 256);
				mame_fwrite(tape_put_file, tape_buffer, 8);
			}
			else
			/* SYSTEM tape ? */
			if (tape_buffer[1] == 0x55)
			{
				char filename[12+1];
				UINT8 zeroes[256] = {0,};

				sprintf(filename, "%-6.6s.cas", tape_buffer+2);
				mame_fopen(SEARCHPATH_IMAGE, filename, OPEN_FLAG_READ | OPEN_FLAG_WRITE, &tape_put_file);
				mame_fwrite(tape_put_file, zeroes, 256);
				mame_fwrite(tape_put_file, tape_buffer, 8);
			}
		}
	}
	else
	{
		if (tape_put_file)
			mame_fwrite(tape_put_file, &value, 1);
	}
}

static void tape_put_close(running_machine *machine)
{
	/* file open ? */
	if (tape_put_file)
	{
		if (put_bit_count)
		{
			UINT8	value;
			while (put_bit_count < 16)
			{
					tape_bits <<= 1;
					put_bit_count++;
			}
			value = 0;
			if (tape_bits & 0x8000) value |= 0x80;
			if (tape_bits & 0x2000) value |= 0x40;
			if (tape_bits & 0x0800) value |= 0x20;
			if (tape_bits & 0x0200) value |= 0x10;
			if (tape_bits & 0x0080) value |= 0x08;
			if (tape_bits & 0x0020) value |= 0x04;
			if (tape_bits & 0x0008) value |= 0x02;
			if (tape_bits & 0x0002) value |= 0x01;
			tape_put_byte(value);
		}
		mame_fclose(tape_put_file);
	}
	tape_count = 0;
	tape_put_file = 0;
}

static void tape_get_byte(void)
{
	int 	count;
	UINT8	value;
	if (tape_get_file)
	{
		count = mame_fread(tape_get_file, &value, 1);
		if (count == 0)
		{
				value = 0;
				mame_fclose(tape_get_file);
				tape_get_file = 0;
		}
		tape_bits |= 0xaaaa;
		if (value & 0x80) tape_bits ^= 0x4000;
		if (value & 0x40) tape_bits ^= 0x1000;
		if (value & 0x20) tape_bits ^= 0x0400;
		if (value & 0x10) tape_bits ^= 0x0100;
		if (value & 0x08) tape_bits ^= 0x0040;
		if (value & 0x04) tape_bits ^= 0x0010;
		if (value & 0x02) tape_bits ^= 0x0004;
		if (value & 0x01) tape_bits ^= 0x0001;
		get_bit_count = 16;
		tape_count++;
	}
}

static void tape_get_open(void)
{
	/* TODO: remove this */
	unsigned char *RAM = memory_region(REGION_CPU1);

	if (!tape_get_file)
	{
		char filename[12+1];

		sprintf(filename, "%-6.6s.cas", RAM + 0x41e8);
		logerror("filename %s\n", filename);
		mame_fopen(SEARCHPATH_IMAGE, filename, OPEN_FLAG_READ, &tape_get_file);
		tape_count = 0;
	}
}

/*************************************
 *
 *				Port handlers.
 *
 *************************************/

 READ8_HANDLER( trs80_port_xx_r )
{
	return 0;
}

WRITE8_HANDLER( trs80_port_ff_w )
{
	int changes = trs80_port_ff ^ data;

	/* tape output changed ? */
	if( changes & 0x03 )
	{
		/* virtual tape ? */
		if( readinputport(0) & 0x20 )
		{
			int now_cycles = activecpu_gettotalcycles();
			int diff = now_cycles - put_cycles;
			UINT8 value;
			/* overrun since last write ? */
			if (diff > 4000)
			{
				/* reset tape output */
				tape_put_close(Machine);
				put_bit_count = tape_bits = in_sync = 0;
			}
			else
			/* just wrote the interesting value ? */
			if( (data & 0x03) == 0x01 )
			{
				/* change within time for a 1 bit ? */
				if( diff < 2000 )
				{
					tape_bits = (tape_bits << 1) | 1;
					/* in sync already ? */
					if( in_sync )
					{
						/* count 1 bit */
						put_bit_count += 1;
					}
					else
					{
						/* try to find sync header A5 */
						if( tape_bits == 0xcc33 )
						{
							in_sync = 1;
							put_bit_count = 16;
						}
					}
				}
				else	/* no change indicates a 0 bit */
				{
					/* shift twice */
					tape_bits <<= 2;
					/* in sync already ? */
					if( in_sync )
						put_bit_count += 2;
				}

				/* collected 8 sync plus 8 data bits ? */
				if( put_bit_count >= 16 )
				{
					/* extract data bits to value */
					value = 0;
					if (tape_bits & 0x8000) value |= 0x80;
					if (tape_bits & 0x2000) value |= 0x40;
					if (tape_bits & 0x0800) value |= 0x20;
					if (tape_bits & 0x0200) value |= 0x10;
					if (tape_bits & 0x0080) value |= 0x08;
					if (tape_bits & 0x0020) value |= 0x04;
					if (tape_bits & 0x0008) value |= 0x02;
					if (tape_bits & 0x0002) value |= 0x01;
					put_bit_count -= 16;
					tape_bits = 0;
					tape_put_byte(value);
				}
			}
			/* remember the cycle count of this write */
			put_cycles = now_cycles;
		}
		else
		{
			switch( data & 0x03 )
			{
			case 0: /* 0.46 volts */
				speaker_level_w(0,1);
				break;
			case 1:
			case 3: /* 0.00 volts */
				speaker_level_w(0,0);
				break;
			case 2: /* 0.85 volts */
				speaker_level_w(0,2);
				break;
			}
		}
	}

	/* font width change ? (32<->64 characters per line) */
	if( changes & 0x08 )
		memset(dirtybuffer, 1, 64 * 16);

	trs80_port_ff = data;
}

 READ8_HANDLER( trs80_port_ff_r )
{
	int now_cycles = activecpu_gettotalcycles();
	/* virtual tape ? */
	if( readinputport(0) & 0x20 )
	{
		int diff = now_cycles - get_cycles;
		/* overrun since last read ? */
		if (diff >= 4000)
		{
			if (tape_get_file)
			{
				mame_fclose(tape_get_file);
				tape_get_file = 0;
			}
			get_bit_count = tape_bits = tape_time = 0;
		}
		else /* check what he will get for input */
		{
			/* count down cycles */
			tape_time -= diff;
			/* time for the next sync or data bit ? */
			if (tape_time <= 0)
			{
				/* approx. time for a bit */
				tape_time += 1570;
				/* need to read get new data ? */
				if (--get_bit_count <= 0)
				{
					tape_get_open();
					tape_get_byte();
				}
				/* shift next sync or data bit to bit 16 */
				tape_bits <<= 1;
				/* if bit is set, set trs80_port_ff bit 4
				   which is then read as bit 7 */
				if (tape_bits & 0x10000)
					trs80_port_ff |= 0x80;
			}
		}
		/* remember the cycle count of this read */
		get_cycles = now_cycles;
	}
	return (trs80_port_ff << 3) & 0xc0;
}

/*************************************
 *
 *		Interrupt handlers.
 *
 *************************************/

INTERRUPT_GEN( trs80_timer_interrupt )
{
	if( (irq_status & IRQ_TIMER) == 0 )
	{
		irq_status |= IRQ_TIMER;
		cpunum_set_input_line (0, 0, HOLD_LINE);
	}
}

INTERRUPT_GEN( trs80_fdc_interrupt )
{
	if ((irq_status & IRQ_FDC) == 0)
	{
		irq_status |= IRQ_FDC;
		cpunum_set_input_line (0, 0, HOLD_LINE);
	}
}

void trs80_fdc_callback(wd17xx_state_t event, void *param)
{
	switch (event)
	{
		case WD17XX_IRQ_CLR:
			irq_status &= ~IRQ_FDC;
			break;
		case WD17XX_IRQ_SET:
			trs80_fdc_interrupt();
			break;
		case WD17XX_DRQ_CLR:
		case WD17XX_DRQ_SET:
			/* do nothing */
			break;
	}
}

INTERRUPT_GEN( trs80_frame_interrupt )
{
}

/*************************************
 *									 *
 *		Memory handlers 			 *
 *									 *
 *************************************/

 READ8_HANDLER ( trs80_printer_r )
{
	/* nothing yet :( */
	return 0;
}

WRITE8_HANDLER( trs80_printer_w )
{
	/* nothing yet :( */
}

 READ8_HANDLER( trs80_irq_status_r )
{
	int result = irq_status;
	irq_status &= ~(IRQ_TIMER | IRQ_FDC);
	return result;
}

WRITE8_HANDLER( trs80_irq_mask_w )
{
	irq_mask = data;
}

WRITE8_HANDLER( trs80_motor_w )
{
	UINT8 drive = 255;

	LOG(("trs80 motor_w $%02X\n", data));

	switch (data)
	{
	case 1:
		drive = 0;
		head = 0;
		break;
	case 2:
		drive = 1;
		head = 0;
		break;
	case 4:
		drive = 2;
		head = 0;
		break;
	case 8:
		drive = 3;
		head = 0;
		break;
	case 9:
		drive = 0;
		head = 1;
		break;
	case 10:
		drive = 1;
		head = 1;
		break;
	case 12:
		drive = 2;
		head = 1;
		break;
	}

	if (drive > 3)
		return;

    wd17xx_set_drive(drive);
	wd17xx_set_side(head);

}

/*************************************
 *		Keyboard					 *
 *************************************/
 READ8_HANDLER( trs80_keyboard_r )
{
	int result = 0;

	if (offset & 1)
		result |= input_port_1_r(0);
	if (offset & 2)
		result |= input_port_2_r(0);
	if (offset & 4)
		result |= input_port_3_r(0);
	if (offset & 8)
		result |= input_port_4_r(0);
	if (offset & 16)
		result |= input_port_5_r(0);
	if (offset & 32)
		result |= input_port_6_r(0);
	if (offset & 64)
		result |= input_port_7_r(0);
	if (offset & 128)
		result |= input_port_8_r(0);

	return result;
}