// license:LGPL-2.1+
// copyright-holders:Angelo Salese, R. Belmont
/***************************************************************************

  machine/stvcd.c - Sega Saturn and ST-V CD-ROM handling

  Another tilt at the windmill in 2011 by R. Belmont.

  Status: All known discs at least load their executable, and many load
          some data files successfully, but there are other problems.

  Information sources:
  - Tyranid's document
  - A commented disassembly I made of the Saturn BIOS's CD code
  - Yabuse's cs2.c
  - The ISO/IEC "Yellow Book" CD-ROM standard, 1995 version

  Address is mostly in terms of FAD (Frame ADdress).
  FAD is absolute number of frames from the start of the disc.
  In other words, FAD = LBA + 150; FAD is the same units as
  LBA except it counts starting at absolute zero instead of
  the first sector (00:02:00 in MSF format).

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

#include "emu.h"
#include "imagedev/chd_cd.h"
#include "includes/stv.h"
#include "cdrom.h"
#include "sound/cdda.h"
#include "debugger.h"
#include "coreutil.h"

// super-verbose
#if 0
#define CDROM_LOG(x) printf x;
#else
#define CDROM_LOG(x)
#endif

// HIRQ definitions
#define CMOK 0x0001 // command dispatch possible
#define DRDY 0x0002 // data transfer preparations complete
#define CSCT 0x0004 // finished reading 1 sector
#define BFUL 0x0008 // CD buffer full
#define PEND 0x0010 // CD playback completed
#define DCHG 0x0020 // disc change / tray open
#define ESEL 0x0040 // selector settings processing complete
#define EHST 0x0080 // host input/output processing complete
#define ECPY 0x0100 // duplication/move processing complete
#define EFLS 0x0200 // file system processing complete
#define SCDQ 0x0400 // subcode Q update completed
#define MPED 0x0800 // MPEG-related processing complete
#define MPCM 0x1000 // MPEG action uncertain
#define MPST 0x2000 // MPEG interrupt status report

// CD status (hi byte of CR1) definitions:
// (these defines are shifted up 8)
#define CD_STAT_BUSY     0x0000     // status change in progress
#define CD_STAT_PAUSE    0x0100     // CD block paused (temporary stop)
#define CD_STAT_STANDBY  0x0200     // CD drive stopped
#define CD_STAT_PLAY     0x0300     // CD play in progress
#define CD_STAT_SEEK     0x0400     // drive seeking
#define CD_STAT_SCAN     0x0500     // drive scanning
#define CD_STAT_OPEN     0x0600     // tray is open
#define CD_STAT_NODISC   0x0700     // no disc present
#define CD_STAT_RETRY    0x0800     // read retry in progress
#define CD_STAT_ERROR    0x0900     // read data error occurred
#define CD_STAT_FATAL    0x0a00     // fatal error (hard reset required)
#define CD_STAT_PERI     0x2000     // periodic response if set, else command response
#define CD_STAT_TRANS    0x4000     // data transfer request if set
#define CD_STAT_WAIT     0x8000     // waiting for command if set, else executed immediately
#define CD_STAT_REJECT   0xff00     // ultra-fatal error.

int saturn_state::get_timing_command(void)
{
	/* TODO: calculate timings based off command params */
	return 16667;
}

/* FIXME: assume Saturn CD-ROMs to have a 2 secs pre-gap for now. */
int saturn_state::get_track_index(UINT32 fad)
{
	UINT32 rel_fad;
	UINT8 track;

	if(cdrom_get_track_type(cdrom, cdrom_get_track(cdrom, fad)) != CD_TRACK_AUDIO)
		return 1;

	track = cdrom_get_track( cdrom, fad );

	rel_fad = fad - cdrom_get_track_start( cdrom, track );

	if(rel_fad < 150)
		return 0;

	return 1;
}

int saturn_state::sega_cdrom_get_adr_control(cdrom_file *file, int track)
{
	return BITSWAP8(cdrom_get_adr_control(file, cur_track),3,2,1,0,7,6,5,4);
}

void saturn_state::cr_standard_return(UINT16 cur_status)
{
	if ((cd_stat & 0x0f00) == CD_STAT_SEEK)
	{
		/* During seek state, values returned are from the target position */
		UINT8 seek_track = cdrom_get_track(cdrom, cd_fad_seek-150);

		cr1 = cur_status | (playtype << 7) | 0x00 | (cdda_repeat_count & 0xf);
		cr2 =  (seek_track == 0xff) ? 0xffff : ((sega_cdrom_get_adr_control(cdrom, seek_track)<<8) | seek_track);
		cr3 = (get_track_index(cd_fad_seek)<<8) | (cd_fad_seek>>16); //index & 0xff00
		cr4 = cd_fad_seek;
	}
	else
	{
		/*
		TODO:
		- Whizz: wpset 0x608f030,4,w,wpdata==0x100&&pc!=0x6040006
		*/
		cr1 = cur_status | (playtype << 7) | 0x00 | (cdda_repeat_count & 0xf); //options << 4 | repeat & 0xf
		cr2 = (cur_track == 0xff) ? 0xffff : ((sega_cdrom_get_adr_control(cdrom, cur_track)<<8) | (cdrom_get_track(cdrom, cd_curfad-150)+1));
		cr3 = (get_track_index(cd_curfad)<<8) | (cd_curfad>>16); //index & 0xff00
		cr4 = cd_curfad;
	}
}

void saturn_state::cd_exec_command( void )
{
	UINT32 temp;

	if(cr1 != 0 &&
		((cr1 & 0xff00) != 0x5100) &&
		((cr1 & 0xff00) != 0x5200) &&
		((cr1 & 0xff00) != 0x5300) &&
		1)
		printf("CD: command exec %04x %04x %04x %04x %04x (stat %04x)\n", hirqreg, cr1, cr2, cr3, cr4, cd_stat);

	switch ((cr1 >> 8) & 0xff)
	{
		case 0x00:
			//CDROM_LOG(("%s:CD: Get Status\n", machine().describe_context()))
			hirqreg |= CMOK;
			if(status_type == 0)
				cr_standard_return(cd_stat);
			else
			{
				cr1 = (cd_stat) | (prev_cr1 & 0xff);
				cr2 = prev_cr2;
				cr3 = prev_cr3;
				cr4 = prev_cr4;
				status_type = 0; /* Road Blaster and friends needs this otherwise they won't boot. */
			}
			//CDROM_LOG(("   = %04x %04x %04x %04x %04x\n", hirqreg, cr1, cr2, cr3, cr4))
			break;

		case 0x01:
			CDROM_LOG(("%s:CD: Get Hardware Info\n", machine().describe_context()))
			hirqreg |= CMOK;
			cr1 = cd_stat;
			cr2 = 0x0201;
			cr3 = 0x0000;
			cr4 = 0x0400;
			status_type = 0;
			break;

		case 0x02:    // Get TOC
			CDROM_LOG(("%s:CD: Get TOC\n", machine().describe_context()))
			cd_readTOC();
			cd_stat = CD_STAT_TRANS|CD_STAT_PAUSE;
			cr1 = cd_stat;
			cr2 = 102*2;    // TOC length in words (102 entries @ 2 words/4bytes each)
			cr3 = 0;
			cr4 = 0;
			xferdnum = 0;
			hirqreg |= (CMOK|DRDY);
			status_type = 0;
			break;

		case 0x03:    // get session info (lower byte = session # to get?)
						// bios is interested in returns in cr3 and cr4
						// cr3 should be data track #
						// cr4 must be > 1 and < 100 or bios gets angry.
			CDROM_LOG(("%s:CD: Get Session Info\n", machine().describe_context()))
			cd_readTOC();
			switch (cr1 & 0xff)
			{
				case 0: // get total session info / disc end
					cd_stat = CD_STAT_PAUSE;
					cr1 = cd_stat;
					cr2 = 0;
					cr3 = 0x0100 | tocbuf[(101*4)+1];
					cr4 = tocbuf[(101*4)+2]<<8 | tocbuf[(101*4)+3];
					break;

				case 1: // get total session info / disc start
					cd_stat = CD_STAT_PAUSE;
					cr1 = cd_stat;
					cr2 = 0;
					cr3 = 0x0100;   // sessions in high byte, session start in lower
					cr4 = 0;
					break;

				default:
					osd_printf_error("CD: Unknown request to Get Session Info %x\n", cr1 & 0xff);
					cr1 = cd_stat;
					cr2 = 0;
					cr3 = 0;
					cr4 = 0;
					break;
			}

			hirqreg |= (CMOK);
			status_type = 0;
			break;

		/* TODO: double check this */
		case 0x04:    // initialize CD system
				// CR1 & 1 = reset software
				// CR1 & 2 = decode RW subcode
				// CR1 & 4 = don't confirm mode 2 subheader
				// CR1 & 8 = retry reading mode 2 sectors
				// CR1 & 10 = force single-speed
				// CR1 & 80 = no change flag (done by Assault Suit Leynos 2)
			CDROM_LOG(("%s:CD: Initialize CD system\n", machine().describe_context()))
			//if((cr1 & 0x81) == 0x00) //guess TODO: nope, Choice Cuts doesn't like it, it crashes if you try to skip the FMV otherwise.
			{
				if(((cd_stat & 0x0f00) != CD_STAT_NODISC) && ((cd_stat & 0x0f00) != CD_STAT_OPEN))
				{
					cd_stat = CD_STAT_PAUSE;
					cd_curfad = 150;
					//cur_track = 1;
					fadstoplay = 0;
				}
				in_buffer = 0;
				buffull = 0;
				hirqreg &= 0xffe5;
				cd_speed = (cr1 & 0x10) ? 1 : 2;

				/* reset filter connections */
				/* Guess: X-Men COTA sequence is 0x48->0x48->0x04(01)->0x04(00)->0x30 then 0x10, without this game throws a FAD reject error */
				/* X-Men vs. SF is even fussier, sequence is  0x04 (1) 0x04 (0) 0x03 (0) 0x03 (1) 0x30 */
				#if 0
				for(int i=0;i<MAX_FILTERS;i++)
				{
					filters[i].fad = 0;
					filters[i].range = 0xffffffff;
					filters[i].mode = 0;
					filters[i].chan = 0;
					filters[i].smmask = 0;
					filters[i].cimask = 0;
					filters[i].fid = 0;
					filters[i].smval = 0;
					filters[i].cival = 0;
				}
				#endif

				/* reset CD device connection */
				//cddevice = (filterT *)nullptr;
			}

			hirqreg |= (CMOK|ESEL);
			cr_standard_return(cd_stat);
			status_type = 0;
			break;

		case 0x06:    // end data transfer (TODO: needs to be worked on!)
				// returns # of bytes transfered (24 bits) in
				// low byte of cr1 (MSB) and cr2 (middle byte, LSB)
			CDROM_LOG(("%s:CD: End data transfer (%d bytes xfer'd)\n", machine().describe_context(), xferdnum))

			// clear the "transfer" flag
			cd_stat &= ~CD_STAT_TRANS;

			if (xferdnum)
			{
				cr1 = (cd_stat) | ((xferdnum>>17) & 0xff);
				cr2 = (xferdnum>>1)&0xffff;
				cr3 = 0;
				cr4 = 0;
			}
			else
			{
				printf("No xferdnum error\n");
				cr1 = (cd_stat) | (0xff);   // is this right?
				cr2 = 0xffff;
				cr3 = 0;
				cr4 = 0;
			}

			// try to clean up any transfers still in progress
			switch (xfertype32)
			{
				case XFERTYPE32_GETSECTOR:
				case XFERTYPE32_PUTSECTOR:
					hirqreg |= EHST;
					break;

				case XFERTYPE32_GETDELETESECTOR:
					if (transpart->size > 0)
					{
						INT32 i;

						xfertype32 = XFERTYPE32_INVALID;

						// deallocate the blocks
						for (i = xfersectpos; i < xfersectpos+xfersectnum; i++)
						{
							cd_free_block(transpart->blocks[i]);
							transpart->blocks[i] = (blockT *)nullptr;
							transpart->bnum[i] = 0xff;
						}

						// defrag what's left
						cd_defragblocks(transpart);

						// clean up our state
						transpart->size -= xferdnum;
						transpart->numblks -= xfersectnum;

						if (freeblocks == 200)
						{
							sectorstore = 0;
						}

						hirqreg |= EHST;
					}
					break;

				default:
					break;
			}


			xferdnum = 0;
			hirqreg |= CMOK;

			CDROM_LOG(("   = %04x %04x %04x %04x %04x\n", hirqreg, cr1, cr2, cr3, cr4))
			status_type = 1;
			break;

		case 0x10: // Play Disc.  FAD is in lowest 7 bits of cr1 and all of cr2.
			UINT32 start_pos,end_pos;
			UINT8 play_mode;

			CDROM_LOG(("%s:CD: Play Disc\n",   machine().describe_context()))
			cd_stat = CD_STAT_PLAY;

			play_mode = (cr3 >> 8) & 0x7f;

			if (!(cr3 & 0x8000))    // preserve current position if bit 7 set
			{
				start_pos = ((cr1&0xff)<<16) | cr2;
				end_pos = ((cr3&0xff)<<16) | cr4;

				if (start_pos & 0x800000)
				{
					if (start_pos != 0xffffff)
						cd_curfad = start_pos & 0xfffff;

					printf("fad mode\n");
					cur_track = cdrom_get_track(cdrom, cd_curfad-150);
				}
				else
				{
					// track mode
					if(((start_pos)>>8) != 0)
					{
						cur_track = (start_pos)>>8;
						cd_fad_seek = cdrom_get_track_start(cdrom, cur_track-1);
						cd_stat = CD_STAT_SEEK;
						machine().device<cdda_device>("cdda")->pause_audio(0);
					}
					else
					{
						/* TODO: Waku Waku 7 sets up track 0, that basically doesn't make any sense. Just skip it for now. */
						popmessage("Warning: track mode == 0, contact MAMEdev");
						cr_standard_return(cd_stat);
						hirqreg |= (CMOK);
						return;
					}

					printf("track mode %d\n",cur_track);
				}

				if (end_pos & 0x800000)
				{
					if (end_pos != 0xffffff)
						fadstoplay = end_pos & 0xfffff;
				}
				else
				{
					UINT8 end_track;

					end_track = (end_pos)>>8;
					fadstoplay = cdrom_get_track_start(cdrom, end_track) - cd_fad_seek;
				}
			}
			else    // play until the end of the disc
			{
				start_pos = ((cr1&0xff)<<16) | cr2;
				end_pos = ((cr3&0xff)<<16) | cr4;

				if(start_pos != 0xffffff)
				{
					/* Madou Monogatari sets 0xff80xxxx as end position, needs investigation ... */
					if(end_pos & 0x800000)
						fadstoplay = end_pos & 0xfffff;
					else
					{
						if(end_pos == 0)
							fadstoplay = (cdrom_get_track_start(cdrom, 0xaa)) - cd_curfad;
						else
							fadstoplay = (cdrom_get_track_start(cdrom, (end_pos & 0xff00) >> 8)) - cd_curfad;
					}
					printf("track mode %08x %08x\n",cd_curfad,fadstoplay);
				}
				else
				{
					/* resume from a pause state */
					/* TODO: Galaxy Fight calls 10ff ffff ffff ffff, but then it calls 0x04->0x02->0x06->0x11->0x04->0x02->0x06 command sequence
					   (and current implementation nukes start/end FAD addresses at 0x04). I'm sure that this doesn't work like this, but there could
					   be countless possible combinations ... */
					if(fadstoplay == 0)
					{
						cd_curfad = cdrom_get_track_start(cdrom, cur_track-1);
						fadstoplay = cdrom_get_track_start(cdrom, cur_track) - cd_curfad;
					}
					printf("track resume %08x %08x\n",cd_curfad,fadstoplay);
				}
			}

			CDROM_LOG(("CD: Play Disc: start %x length %x\n", cd_curfad, fadstoplay))

			cr_standard_return(cd_stat);
			hirqreg |= (CMOK);
			oddframe = 0;
			in_buffer = 0;

			playtype = 0;

			// cdda
			if(cdrom_get_track_type(cdrom, cdrom_get_track(cdrom, cd_curfad)) == CD_TRACK_AUDIO)
			{
				machine().device<cdda_device>("cdda")->pause_audio(0);
				//machine().device<cdda_device>("cdda")->start_audio(cd_curfad, fadstoplay);
				//cdda_repeat_count = 0;
			}

			if(play_mode != 0x7f)
				cdda_maxrepeat = play_mode & 0xf;
			else
				cdda_maxrepeat = 0;

			cdda_repeat_count = 0;
			status_type = 0;
			break;

		case 0x11: // disc seek
			CDROM_LOG(("%s:CD: Disc seek\n",   machine().describe_context()))
			//printf("%08x %08x %08x %08x\n",cr1,cr2,cr3,cr4);
			if (cr1 & 0x80)
			{
				temp = (cr1&0xff)<<16;  // get FAD to seek to
				temp |= cr2;

				//cd_curfad = temp;

				if (temp == 0xffffff)
				{
					cd_stat = CD_STAT_PAUSE;
					machine().device<cdda_device>("cdda")->pause_audio(1);
				}
				else
				{
					cd_curfad = ((cr1&0x7f)<<16) | cr2;
					printf("disc seek with params %04x %04x\n",cr1,cr2); //Area 51 sets this up
				}
			}
			else
			{
				// is it a valid track?
				if (cr2 >> 8)
				{
					cd_stat = CD_STAT_PAUSE;
					cur_track = cr2>>8;;
					cd_curfad = cdrom_get_track_start(cdrom, cur_track-1);
					machine().device<cdda_device>("cdda")->pause_audio(1);
					// (index is cr2 low byte)
				}
				else // error!
				{
					cd_stat = CD_STAT_STANDBY;
					cd_curfad = 0xffffffff;
					cur_track = 0xff;
					machine().device<cdda_device>("cdda")->stop_audio(); //stop any pending CD-DA
				}
			}


			hirqreg |= CMOK;
			cr_standard_return(cd_stat);
			status_type = 0;
			break;

		case 0x12: // FFWD / REW
			//cr1 bit 0 determines if this is a Fast Forward (0) or a Rewind (1) command
			// ...
			break;

		case 0x20: // Get SubCode Q / RW Channel
			switch(cr1 & 0xff)
			{
				case 0: // Get Q
				{
					UINT32 msf_abs,msf_rel;
					UINT8 track;
					cr1 = cd_stat | 0;
					cr2 = 10/2;
					cr3 = 0;
					cr4 = 0;

					/*
					Subcode Q info should be:
					---- --x- S0
					---- ---x S1
					xxxx ---- [0] Control (bit 7 Pre-emphasis, bit 6: copy permitted, bit 5 undefined, bit 4 number of channels)
					---- xxxx [0] address (0x0001 Mode 1)
					xxxx xxxx [1] track number (1-99, AA lead-out), BCD format
					xxxx xxxx [2] index (01 lead-out), BCD format
					xxxx xxxx [3] Time within' track M
					xxxx xxxx [4] Time within' track S
					xxxx xxxx [5] Time within' track F
					xxxx xxxx [6] Zero
					xxxx xxxx [7] Absolute M
					xxxx xxxx [8] Absolute S
					xxxx xxxx [9] Absolute F
					xxxx xxxx [10] CRCC
					xxxx xxxx [11] CRCC
					*/

					msf_abs = lba_to_msf_alt( cd_curfad - 150 );
					track = cdrom_get_track( cdrom, cd_curfad );
					msf_rel = lba_to_msf_alt( cd_curfad - 150 - cdrom_get_track_start( cdrom, track ) );

					xfertype = XFERTYPE_SUBQ;
					xfercount = 0;
					subqbuf[0] = 0x01 | ((cdrom_get_track_type(cdrom, cdrom_get_track(cdrom, track+1)) == CD_TRACK_AUDIO) ? 0x00 : 0x40);
					subqbuf[1] = dec_2_bcd(track+1);
					subqbuf[2] = dec_2_bcd(get_track_index(cd_curfad));
					subqbuf[3] = dec_2_bcd((msf_rel >> 16) & 0xff);
					subqbuf[4] = dec_2_bcd((msf_rel >> 8) & 0xff);
					subqbuf[5] = dec_2_bcd((msf_rel >> 0) & 0xff);
					subqbuf[6] = 0;
					subqbuf[7] = dec_2_bcd((msf_abs >> 16) & 0xff);
					subqbuf[8] = dec_2_bcd((msf_abs >> 8) & 0xff);
					subqbuf[9] = dec_2_bcd((msf_abs >> 0) & 0xff);
				}
				break;

				case 1: // Get RW
					cr1 = cd_stat | 0;
					cr2 = 12;
					cr3 = 0;
					cr4 = 0;

					xfertype = XFERTYPE_SUBRW;
					xfercount = 0;

					/* return null data for now */
					{
						int i;

						for(i=0;i<12*2;i++)
							subrwbuf[i] = 0;
					}
					break;
			}
			hirqreg |= CMOK|DRDY;
			status_type = 0;
			break;

		case 0x30:    // Set CD Device connection
			{
				UINT8 parm;

				// get operation
				parm = cr3>>8;

				CDROM_LOG(("%s:CD: Set CD Device Connection filter # %x\n",   machine().describe_context(), parm))

				cddevicenum = parm;

				if (parm == 0xff)
				{
					cddevice = (filterT *)nullptr;
				}
				else
				{
					if (parm < 0x24)
					{
						cddevice = &filters[(cr3>>8)];
					}
				}


				hirqreg |= (CMOK|ESEL);
				cr_standard_return(cd_stat);
				status_type = 0;
			}
			break;

		case 0x31:
			popmessage("Get CD Device Connection, contact MAMEdev");
			hirqreg |= CMOK;
			break;

		case 0x32:    // Last Buffer Destination
			cr1 = cd_stat | 0;
			cr2 = 0;
			cr3 = lastbuf << 8;
			cr4 = 0;
			hirqreg |= (CMOK);
			status_type = 0;
			break;

		case 0x40:    // Set Filter Range
						// cr1 low + cr2 = FAD0, cr3 low + cr4 = FAD1
						// cr3 hi = filter num.
			{
				UINT8 fnum = (cr3>>8)&0xff;

				CDROM_LOG(("%s:CD: Set Filter Range\n",   machine().describe_context()))

				filters[fnum].fad = ((cr1 & 0xff)<<16) | cr2;
				filters[fnum].range = ((cr3 & 0xff)<<16) | cr4;

				printf("%08x %08x %d\n",filters[fnum].fad,filters[fnum].range,fnum);

				hirqreg |= (CMOK|ESEL);
				cr_standard_return(cd_stat);
				status_type = 0;
			}
			break;

		case 0x41:
			popmessage("Get Filter Range, contact MAMEdev");
			hirqreg |= CMOK;
			break;

		case 0x42:    // Set Filter Subheader conditions
			{
				UINT8 fnum = (cr3>>8)&0xff;

				CDROM_LOG(("%s:CD: Set Filter Subheader conditions %x => chan %x masks %x fid %x vals %x\n", machine().describe_context(), fnum, cr1&0xff, cr2, cr3&0xff, cr4))

				filters[fnum].chan = cr1 & 0xff;
				filters[fnum].smmask = (cr2>>8)&0xff;
				filters[fnum].cimask = cr2&0xff;
				filters[fnum].fid = cr3&0xff;
				filters[fnum].smval = (cr4>>8)&0xff;
				filters[fnum].cival = cr4&0xff;

				hirqreg |= (CMOK|ESEL);
				cr_standard_return(cd_stat);
				status_type = 0;
			}
			break;

		case 0x43:    // Get Filter Subheader conditions
			{
				UINT8 fnum = (cr3>>8)&0xff;

				CDROM_LOG(("%s:CD: Set Filter Subheader conditions %x => chan %x masks %x fid %x vals %x\n", machine().describe_context(), fnum, cr1&0xff, cr2, cr3&0xff, cr4))

				cr1 = cd_stat | (filters[fnum].chan & 0xff);
				cr2 = (filters[fnum].smmask << 8) | (filters[fnum].cimask & 0xff);
				cr3 = filters[fnum].fid;
				cr4 = (filters[fnum].smval << 8) | (filters[fnum].cival & 0xff);

				hirqreg |= (CMOK|ESEL);
				status_type = 0;
			}
			break;

		case 0x44:    // Set Filter Mode
			{
				UINT8 fnum = (cr3>>8)&0xff;
				UINT8 mode = (cr1 & 0xff);

				// initialize filter?
				if (mode & 0x80)
				{
					memset(&filters[fnum], 0, sizeof(filterT));
				}
				else
				{
					filters[fnum].mode = mode;
				}

				CDROM_LOG(("%s:CD: Set Filter Mode filt %x mode %x\n", machine().describe_context(), fnum, mode))
				hirqreg |= (CMOK|ESEL);
				cr_standard_return(cd_stat);
				status_type = 0;
			}
			break;

		case 0x45:    // Get Filter Mode
			{
				UINT8 fnum = (cr3>>8)&0xff;

				cr1 = cd_stat | (filters[fnum].mode & 0xff);
				cr2 = 0;
				cr3 = 0;
				cr4 = 0;

				hirqreg |= (CMOK|ESEL);
				status_type = 0;
			}
			break;

		case 0x46:    // Set Filter Connection
			{
				/* TODO: maybe condition false is cr3 low? */
				UINT8 fnum = (cr3>>8)&0xff;

				CDROM_LOG(("%s:CD: Set Filter Connection %x => mode %x parm %04x\n", machine().describe_context(), fnum, cr1 & 0xf, cr2))

				if (cr1 & 1)    // set true condition
					filters[fnum].condtrue = (cr2>>8)&0xff;

				if (cr1 & 2)    // set false condition
					filters[fnum].condfalse = cr2&0xff;

				hirqreg |= (CMOK|ESEL);
				cr_standard_return(cd_stat);
				status_type = 0;
			}
			break;

		case 0x48:    // Reset Selector
			{
			int i,j;

			CDROM_LOG(("%s:CD: Reset Selector\n",   machine().describe_context()))

			if((cr1 & 0xff) == 0x00)
			{
				UINT8 bufnum = cr3>>8;

				if(bufnum < MAX_FILTERS)
				{
					for (i = 0; i < MAX_BLOCKS; i++)
					{
						cd_free_block(partitions[bufnum].blocks[i]);
						partitions[bufnum].blocks[i] = (blockT *)nullptr;
						partitions[bufnum].bnum[i] = 0xff;
					}

					partitions[bufnum].size = -1;
					partitions[bufnum].numblks = 0;
				}

				// TODO: buffer full flag

				if (freeblocks == 200) { sectorstore = 0; }

				hirqreg |= (CMOK|ESEL);
				cr_standard_return(cd_stat);
				status_type = 0;
				return;
			}

			/* reset false filter output conditions */
			/* TODO: check these two. */
			if(cr1 & 0x80)
			{
				for(i=0;i<MAX_FILTERS;i++)
					filters[i].condfalse = 0;
			}

			/* reset true filter output conditions */
			if(cr1 & 0x40)
			{
				for(i=0;i<MAX_FILTERS;i++)
					filters[i].condtrue = 0;
			}

			/* reset filter conditions*/
			if(cr1 & 0x10)
			{
				for(i=0;i<MAX_FILTERS;i++)
				{
					filters[i].fad = 0;
					filters[i].range = 0xffffffff;
					filters[i].mode = 0;
					filters[i].chan = 0;
					filters[i].smmask = 0;
					filters[i].cimask = 0;
					filters[i].fid = 0;
					filters[i].smval = 0;
					filters[i].cival = 0;
				}
			}

			/* reset partition buffer data */
			if(cr1 & 0x4)
			{
				for(i=0;i<MAX_FILTERS;i++)
				{
					for (j = 0; j < MAX_BLOCKS; j++)
					{
						cd_free_block(partitions[i].blocks[j]);
						partitions[i].blocks[j] = (blockT *)nullptr;
						partitions[i].bnum[j] = 0xff;
					}

					partitions[i].size = -1;
					partitions[i].numblks = 0;
				}

				buffull = sectorstore = 0;
			}

			hirqreg |= (CMOK|ESEL);
			cr_standard_return(cd_stat);
			status_type = 0;
			}
			break;

		case 0x50:    // get Buffer Size
			cr1 = cd_stat;
			cr2 = (freeblocks > 200) ? 200 : freeblocks;
			cr3 = 0x1800;
			cr4 = 200;
			CDROM_LOG(("CD: Get Buffer Size = %d\n", cr2))
			hirqreg |= (CMOK);
			status_type = 0;
			break;

		case 0x51:    // get # sectors used in a buffer
			{
				UINT32 bufnum = cr3>>8;

				CDROM_LOG(("%s:CD: Get Sector Number (bufno %d) = %d blocks\n",   machine().describe_context(), bufnum, cr4))
				cr1 = cd_stat;
				cr2 = 0;
				cr3 = 0;
				if(cr1 & 0xff || cr2 || cr3 & 0xff || cr4)
					printf("Get # sectors used with params %04x %04x %04x %04x\n",cr1,cr2,cr3,cr4);

				// is the partition empty?
				if (partitions[bufnum].size == -1)
				{
					cr4 = 0;
				}
				else
				{
					cr4 = partitions[bufnum].numblks;
					//printf("Partition %08x %04x\n",bufnum,cr4);
				}

				//printf("%04x\n",cr4);
				if(cr4 == 0)
					hirqreg |= (CMOK);
				else
					hirqreg |= (CMOK|DRDY);
				status_type = 1;
			}
			break;

		case 0x52:    // calculate actual size
			{
				UINT32 bufnum = cr3>>8;
				UINT32 sectoffs = cr2;
				UINT32 numsect = cr4;

				CDROM_LOG(("%s:CD: Calculate actual size: buf %x offs %x numsect %x\n", machine().describe_context(), bufnum, sectoffs, numsect))

				calcsize = 0;
				if (partitions[bufnum].size != -1)
				{
					INT32 i;

					for (i = 0; i < numsect; i++)
					{
						if (partitions[bufnum].blocks[sectoffs+i])
						{
							calcsize += (partitions[bufnum].blocks[sectoffs+i]->size / 2);
						}
					}
				}

				hirqreg |= (CMOK|ESEL);
				cr_standard_return(cd_stat);
				status_type = 0;
			}
			break;

		case 0x53:    // get actual block size
			CDROM_LOG(("%s:CD: Get actual block size\n", machine().describe_context()))
			cr1 = cd_stat | ((calcsize>>16)&0xff);
			cr2 = (calcsize & 0xffff);
			cr3 = 0;
			cr4 = 0;
			hirqreg |= (CMOK|ESEL);
			status_type = 1;
			break;

		case 0x54:    // get sector info
			{
				UINT32 sectoffs = cr2 & 0xff;
				UINT32 bufnum = cr3>>8;

				if (bufnum >= MAX_FILTERS || !partitions[bufnum].blocks[sectoffs])
				{
					cr1 |= CD_STAT_REJECT & 0xff00;
					hirqreg |= (CMOK|ESEL);
					printf("Get sector info reject\n");
				}
				else
				{
					cr1 = cd_stat | ((partitions[bufnum].blocks[sectoffs]->FAD >> 16) & 0xff);
					cr2 = partitions[bufnum].blocks[sectoffs]->FAD & 0xffff;
					cr3 = ((partitions[bufnum].blocks[sectoffs]->fnum & 0xff) << 8) | (partitions[bufnum].blocks[sectoffs]->chan & 0xff);
					cr4 = ((partitions[bufnum].blocks[sectoffs]->subm & 0xff) << 8) | (partitions[bufnum].blocks[sectoffs]->cinf & 0xff);
					hirqreg |= (CMOK|ESEL);
				}

				status_type = 0;
			}
			break;

		case 0x60:    // set sector length
			CDROM_LOG(("%s:CD: Set sector length\n",   machine().describe_context()))

			switch (cr1 & 0xff)
			{
				case 0:
					sectlenin = 2048;
					break;
				case 1:
					sectlenin = 2336;
					break;
				case 2:
					sectlenin = 2340;
					break;
				case 3:
					sectlenin = 2352;
					break;
			}

			switch ((cr2>>8) & 0xff)
			{
				case 0:
					sectlenout = 2048;
					break;
				case 1:
					sectlenout = 2336;
					break;
				case 2:
					sectlenout = 2340;
					break;
				case 3:
					sectlenout = 2352;
					break;
			}
			hirqreg |= (CMOK|ESEL);
			cr_standard_return(cd_stat);
			status_type = 0;
			break;

		case 0x61:    // get sector data
			{
				UINT32 sectnum = cr4;
				UINT32 sectofs = cr2;
				UINT32 bufnum = cr3>>8;

				CDROM_LOG(("%s:CD: Get sector data (SN %d SO %d BN %d)\n",   machine().describe_context(), sectnum, sectofs, bufnum))

				if (bufnum >= MAX_FILTERS)
				{
					printf("CD: invalid buffer number\n");
					/* TODO: why this is happening? */
					cr_standard_return(CD_STAT_REJECT);
					hirqreg |= (CMOK|EHST);
					return;
				}

				if (partitions[bufnum].numblks < sectnum)
				{
					printf("CD: buffer is not full %08x %08x\n",partitions[bufnum].numblks,sectnum);
					cr_standard_return(CD_STAT_REJECT);
					hirqreg |= (CMOK|EHST);
					return;
				}

				cd_getsectoroffsetnum(bufnum, &sectofs, &sectnum);

				xfertype32 = XFERTYPE32_GETSECTOR;
				xferoffs = 0;
				xfersect = 0;
				xferdnum = 0;
				xfersectpos = sectofs;
				xfersectnum = sectnum;
				transpart = &partitions[bufnum];

				cd_stat |= CD_STAT_TRANS;
				cr_standard_return(cd_stat);
				hirqreg |= (CMOK|EHST|DRDY);
				status_type = 0;
			}
			break;

		case 0x62:    // delete sector data
			{
				UINT32 sectnum = cr4;
				UINT32 sectofs = cr2;
				UINT32 bufnum = cr3>>8;
				INT32 i;

				CDROM_LOG(("%s:CD: Delete sector data (SN %d SO %d BN %d)\n",   machine().describe_context(), sectnum, sectofs, bufnum))

				if (bufnum >= MAX_FILTERS)
				{
					printf("CD: invalid buffer number\n");
					/* TODO: why this is happening? */
					cr_standard_return(CD_STAT_REJECT);
					hirqreg |= (CMOK|EHST);
					return;
				}

				/* TODO: Phantasy Star 2 throws this one. */
				if (partitions[bufnum].numblks == 0)
				{
					printf("CD: buffer is already empty\n");
					cr_standard_return(CD_STAT_REJECT);
					hirqreg |= (CMOK|EHST);
					return;
				}

				cd_getsectoroffsetnum(bufnum, &sectofs, &sectnum);

				for (i = sectofs; i < (sectofs + sectnum); i++)
				{
					partitions[bufnum].size -= partitions[bufnum].blocks[i]->size;
					cd_free_block(partitions[bufnum].blocks[i]);
					partitions[bufnum].blocks[i] = (blockT *)nullptr;
					partitions[bufnum].bnum[i] = 0xff;
				}

				cd_defragblocks(&partitions[bufnum]);

				partitions[bufnum].numblks -= sectnum;

				if (freeblocks == 200)
				{
					sectorstore = 0;
				}

				cd_stat &= ~CD_STAT_TRANS;
				cr_standard_return(cd_stat);
				hirqreg |= (CMOK|EHST);
				status_type = 0;
			}
			break;

		case 0x63:    // get then delete sector data
			{
				UINT32 sectnum = cr4;
				UINT32 sectofs = cr2;
				UINT32 bufnum = cr3>>8;

				CDROM_LOG(("%s:CD: Get and delete sector data (SN %d SO %d BN %d)\n",   machine().describe_context(), sectnum, sectofs, bufnum))

				if (bufnum >= MAX_FILTERS)
				{
					printf("CD: invalid buffer number\n");
					/* TODO: why this is happening? */
					cr_standard_return(CD_STAT_REJECT);
					hirqreg |= (CMOK|EHST);
					return;
				}

				/* Yoshimoto Mahjong uses the REJECT status to verify when the data is ready. */
				if (partitions[bufnum].numblks < sectnum)
				{
					printf("CD: buffer is not full %08x %08x\n",partitions[bufnum].numblks,sectnum);
					cr_standard_return(CD_STAT_REJECT);
					hirqreg |= (CMOK|EHST);
					return;
				}

				cd_getsectoroffsetnum(bufnum, &sectofs, &sectnum);

				xfertype32 = XFERTYPE32_GETDELETESECTOR;
				xferoffs = 0;
				xfersect = 0;
				xferdnum = 0;
				xfersectpos = sectofs;
				xfersectnum = sectnum;
				transpart = &partitions[bufnum];

				cd_stat |= CD_STAT_TRANS;
				cr_standard_return(cd_stat);
				hirqreg |= (CMOK|EHST|DRDY);
				status_type = 0;
			}
			break;

		case 0x64:    // put sector data
			/* After Burner 2, Out Run, Fantasy Zone and Dungeon Master Nexus trips this */
			{
				UINT32 sectnum = cr4 & 0xff;
				UINT32 sectofs = cr2;
				UINT32 bufnum = cr3>>8;

				xfertype32 = XFERTYPE32_PUTSECTOR;

				/*TODO: eventual errors? */

				cd_getsectoroffsetnum(bufnum, &sectofs, &sectnum);

				cd_stat |= CD_STAT_TRANS;

				xferoffs = 0;
				xfersect = 0;
				xferdnum = 0;
				xfersectpos = sectofs;
				xfersectnum = sectnum;
				transpart = &partitions[bufnum];

				// allocate the blocks
				for (int i = xfersectpos; i < xfersectpos+xfersectnum; i++)
				{
					transpart->blocks[i] = cd_alloc_block(&transpart->bnum[i]);
					if(transpart->size == -1)
						transpart->size = 0;
					transpart->size += transpart->blocks[i]->size;
					transpart->numblks++;
				}
			}

			hirqreg |= (CMOK|DRDY);
			cr_standard_return(cd_stat);
			status_type = 0;
			break;

		case 0x65:
			popmessage("Move Sector data, contact MAMEdev");
			hirqreg |= (CMOK);
			break;

		case 0x66:    // copy sector data
			/* TODO: Sword & Sorcery / Riglord Saga 2 */
			{
				UINT32 src_filter = (cr3>>8)&0xff;
				UINT32 dst_filter = cr1&0xff;
				UINT32 sectnum = cr4 & 0xff;

				//cd_stat |= CD_STAT_TRANS;
				//transpart = &partitions[dst_filter];

				for (int i = 0; i < sectnum; i++)
				{
					// allocate the dst blocks
					partitions[dst_filter].blocks[i] = cd_alloc_block(&partitions[dst_filter].bnum[i]);
					if(partitions[dst_filter].size == -1)
						partitions[dst_filter].size = 0;
					partitions[dst_filter].size += partitions[dst_filter].blocks[i]->size;
					partitions[dst_filter].numblks++;

					//copy data
					for(int j = 0; j < sectlenin; j++)
						partitions[dst_filter].blocks[i]->data[j] = partitions[src_filter].blocks[i]->data[j];

					//deallocate the src blocks
					//partitions[src_filter].size -= partitions[src_filter].blocks[i]->size;
					//cd_free_block(partitions[src_filter].blocks[i]);
					//partitions[src_filter].blocks[i] = (blockT *)nullptr;
					//partitions[src_filter].bnum[i] = 0xff;
				}

			}

			hirqreg |= (CMOK|ECPY);
			cr_standard_return(cd_stat);
			status_type = 0;
			break;


		case 0x67:    // get copy error
			CDROM_LOG(("%s:CD: Get copy error\n",   machine().describe_context()))
			printf("Get copy error\n");
			cr1 = cd_stat;
			cr2 = 0;
			cr3 = 0;
			cr4 = 0;
			hirqreg |= (CMOK);
			status_type = 0;
			break;

		case 0x70:    // change directory
			CDROM_LOG(("%s:CD: Change Directory\n",   machine().describe_context()))
			hirqreg |= (CMOK|EFLS);

			temp = (cr3&0xff)<<16;
			temp |= cr4;

			read_new_dir(temp);
			cr_standard_return(cd_stat);
			status_type = 0;
			break;

		case 0x71:    // Read directory entry
			CDROM_LOG(("%s:CD: Read Directory Entry\n",   machine().describe_context()))
//          UINT32 read_dir;

//          read_dir = ((cr3&0xff)<<16)|cr4;

			if((cr3 >> 8) < 0x24)
				cddevice = &filters[cr3 >> 8];
			else
				cddevice = (filterT *)nullptr;

			/* TODO:  */
			//read_new_dir(read_dir - 2);

			cr_standard_return(cd_stat);
			hirqreg |= (CMOK|EFLS);
			status_type = 0;
			break;

		case 0x72:    // Get file system scope
			CDROM_LOG(("CD: Get file system scope\n"))
			hirqreg |= (CMOK|EFLS);
			cr1 = cd_stat;
			cr2 = numfiles; // # of files in directory
			cr3 = 0x0100;   // report directory held
			cr4 = firstfile;    // first file id
			printf("%04x %04x %04x %04x\n",cr1,cr2,cr3,cr4);
			status_type = 0;
			break;

		case 0x73:    // Get File Info
			CDROM_LOG(("%s:CD: Get File Info\n",   machine().describe_context()))
			cd_stat |= CD_STAT_TRANS;
			cd_stat &= 0xff00;      // clear top byte of return value
			playtype = 0;
			cdda_repeat_count = 0;
			hirqreg |= (CMOK|DRDY);

			temp = (cr3&0xff)<<16;
			temp |= cr4;

			if (temp == 0xffffff)   // special
			{
				xfertype = XFERTYPE_FILEINFO_254;
				xfercount = 0;

				cr1 = cd_stat;
				cr2 = 0x5f4;
				cr3 = 0;
				cr4 = 0;
			}
			else
			{
				cr1 = cd_stat;
				cr2 = 6;    // 6 words for single file
							// first 4 bytes = FAD address
							// second 4 bytes = length
							// last 4 bytes:
							// - unit size
							// - gap size
							// - file #
							// attributes flags

				cr3 = 0;
				cr4 = 0;

				printf("%08x %08x\n",curdir[temp].firstfad,curdir[temp].length);
				// first 4 bytes = FAD
				finfbuf[0] = (curdir[temp].firstfad>>24)&0xff;
				finfbuf[1] = (curdir[temp].firstfad>>16)&0xff;
				finfbuf[2] = (curdir[temp].firstfad>>8)&0xff;
				finfbuf[3] = (curdir[temp].firstfad&0xff);
				// second 4 bytes = length of file
				finfbuf[4] = (curdir[temp].length>>24)&0xff;
				finfbuf[5] = (curdir[temp].length>>16)&0xff;
				finfbuf[6] = (curdir[temp].length>>8)&0xff;
				finfbuf[7] = (curdir[temp].length&0xff);
				finfbuf[8] = curdir[temp].interleave_gap_size;
				finfbuf[9] = curdir[temp].file_unit_size;
				finfbuf[10] = temp;
				finfbuf[11] = curdir[temp].flags;

				xfertype = XFERTYPE_FILEINFO_1;
				xfercount = 0;
			}
			CDROM_LOG(("   = %04x %04x %04x %04x %04x\n", hirqreg, cr1, cr2, cr3, cr4))
			status_type = 0;
			break;

		case 0x74:    // Read File
			CDROM_LOG(("%s:CD: Read File\n",   machine().describe_context()))
			UINT16 file_offset,file_filter,file_id,file_size;

			file_offset = ((cr1 & 0xff)<<8)|(cr2 & 0xff); /* correct? */
			file_filter = cr3 >> 8;
			file_id = ((cr3 & 0xff) << 16)|(cr4);
			file_size = ((curdir[file_id].length + sectlenin - 1) / sectlenin) - file_offset;

			cd_stat = CD_STAT_PLAY|0x80;    // set "cd-rom" bit
			cd_curfad = (curdir[file_id].firstfad + file_offset);
			fadstoplay = file_size;
			if(file_filter < 0x24)
				cddevice = &filters[file_filter];
			else
				cddevice = (filterT *)nullptr;

			printf("Read file %08x (%08x %08x) %02x %d\n",curdir[file_id].firstfad,cd_curfad,fadstoplay,file_filter,sectlenin);

			cr_standard_return(cd_stat);

			oddframe = 0;
			in_buffer = 0;

			playtype = 1;

			hirqreg |= (CMOK|EHST);
			status_type = 0;
			break;

		case 0x75:
			CDROM_LOG(("%s:CD: Abort File\n",   machine().describe_context()))
			// bios expects "2bc" mask to work against this
			hirqreg |= (CMOK|EFLS);
			sectorstore = 0;
			xfertype32 = XFERTYPE32_INVALID;
			xferdnum = 0;
			if(((cd_stat & 0x0f00) != CD_STAT_NODISC) && ((cd_stat & 0x0f00) != CD_STAT_OPEN))
				cd_stat = CD_STAT_PAUSE;    // force to pause
			cr_standard_return(cd_stat);
			status_type = 0;
			break;

		case 0xe0:    // appears to be copy protection check.  needs only to return OK.
			CDROM_LOG(("%s:CD: Verify copy protection\n",   machine().describe_context()))
			if(((cd_stat & 0x0f00) != CD_STAT_NODISC) && ((cd_stat & 0x0f00) != CD_STAT_OPEN))
				cd_stat = CD_STAT_PAUSE;
//          cr1 = cd_stat;  // necessary to pass
//          cr2 = 0x4;
//          hirqreg |= (CMOK|EFLS|CSCT);
			sectorstore = 1;
			hirqreg = 0xfc5;
			cr_standard_return(cd_stat);
			status_type = 0;
			break;

		case 0xe1:    // get disc region
			CDROM_LOG(("%s:CD: Get disc region\n",   machine().describe_context()))
			if(cd_stat != CD_STAT_NODISC && cd_stat != CD_STAT_OPEN)
				cd_stat = CD_STAT_PAUSE;
			cr1 = cd_stat;  // necessary to pass
			cr2 = 0x4;      // (must return this value to pass bios checks)
			cr3 = 0;
			cr4 = 0;
			hirqreg |= (CMOK);
//          cr_standard_return(cd_stat);
			status_type = 0;
			break;

		default:
			CDROM_LOG(("CD: Unknown command %04x\n", cr1>>8))
			popmessage("CD Block unknown command %02x, contact MAMEdev",cr1>>8);
			hirqreg |= (CMOK);
			break;
	}

	if(status_type == 1)
	{
		prev_cr1 = cr1;
		prev_cr2 = cr2;
		prev_cr3 = cr3;
		prev_cr4 = cr4;
	}
}

TIMER_DEVICE_CALLBACK_MEMBER( saturn_state::stv_sh1_sim )
{
	if((cmd_pending == 0xf) && (!(hirqreg & CMOK)))
		cd_exec_command();
}

TIMER_DEVICE_CALLBACK_MEMBER( saturn_state::stv_sector_cb )
{
	//sector_timer->reset();

	//popmessage("%08x %08x %d %d",cd_curfad,fadstoplay,cmd_pending,cd_speed);

	cd_playdata();

	if(cdrom_get_track_type(cdrom, cdrom_get_track(cdrom, cd_curfad)) == CD_TRACK_AUDIO)
		sector_timer->adjust(attotime::from_hz(75));    // 75 sectors / second = 150kBytes/second (cdda track ignores cd_speed setting)
	else
		sector_timer->adjust(attotime::from_hz(75*cd_speed));   // 75 / 150 sectors / second = 150 / 300kBytes/second

	/* TODO: doesn't boot if a disk isn't in? */
	/* TODO: Check out when this really happens. (Daytona USA original version definitely wants it to be on).*/
	//if(((cd_stat & 0x0f00) != CD_STAT_NODISC) && ((cd_stat & 0x0f00) != CD_STAT_OPEN))
		hirqreg |= SCDQ;

	if(cd_stat & CD_STAT_PERI)
	{
		cr_standard_return(cd_stat);
	}
}

// global functions
void saturn_state::stvcd_reset( void )
{
	INT32 i, j;

	hirqmask = 0xffff;
	hirqreg = 0xffff;
	cr1 = 'C';
	cr2 = ('D'<<8) | 'B';
	cr3 = ('L'<<8) | 'O';
	cr4 = ('C'<<8) | 'K';
	cd_stat = CD_STAT_PAUSE;
	cd_stat |= CD_STAT_PERI;
	cur_track = 0xff;

	curdir.clear();

	xfertype = XFERTYPE_INVALID;
	xfertype32 = XFERTYPE32_INVALID;

	// reset flag vars
	buffull = sectorstore = 0;

	freeblocks = 200;

	sectlenin = sectlenout = 2048;

	lastbuf = 0xff;

	// reset buffer partitions
	for (i = 0; i < MAX_FILTERS; i++)
	{
		partitions[i].size = -1;
		partitions[i].numblks = 0;

		for (j = 0; j < MAX_BLOCKS; j++)
		{
			partitions[i].blocks[j] = (blockT *)nullptr;
			partitions[i].bnum[j] = 0xff;
		}
	}

	// reset blocks
	for (i = 0; i < MAX_BLOCKS; i++)
	{
		blocks[i].size = -1;
		memset(&blocks[i].data, 0, CD_MAX_SECTOR_DATA);
	}

	// open device
	if (cdrom)
	{
		cdrom_close(cdrom);
		cdrom = (cdrom_file *)nullptr;
	}

	cdrom_image_device *cddevice = machine().device<cdrom_image_device>("cdrom");
	if (cddevice!=nullptr)
	{
		// MESS case
		cdrom = cddevice->get_cdrom_file();
	}
	else
	{
		// MAME case
		cdrom = cdrom_open(machine().rom_load().get_disk_handle("cdrom"));
	}

	machine().device<cdda_device>("cdda")->set_cdrom(cdrom);

	if (cdrom)
	{
		CDROM_LOG(("Opened CD-ROM successfully, reading root directory\n"))
		read_new_dir(0xffffff);    // read root directory
	}
	else
	{
		cd_stat = CD_STAT_NODISC;
	}

	cd_speed = 2;
	cdda_repeat_count = 0;
	tray_is_closed = 1;

	sector_timer = machine().device<timer_device>("sector_timer");
	sector_timer->adjust(attotime::from_hz(150));   // 150 sectors / second = 300kBytes/second
	sh1_timer = machine().device<timer_device>("sh1_cmd");
}

saturn_state::blockT *saturn_state::cd_alloc_block(UINT8 *blknum)
{
	INT32 i;

	// search the 200 available blocks for a free one
	for (i = 0; i < 200; i++)
	{
		if (blocks[i].size == -1)
		{
			freeblocks--;
			if (freeblocks <= 0)
			{
				buffull = 1;
				printf("buffull in cd_alloc_block\n");
			}

			blocks[i].size = sectlenin;
			*blknum = i;

			CDROM_LOG(("CD: allocating block %d, size %x\n", i, sectlenin))

			return &blocks[i];
		}
	}

	buffull = 1;
	return (blockT *)nullptr;
}

void saturn_state::cd_free_block(blockT *blktofree)
{
	INT32 i;

	CDROM_LOG(("cd_free_block: %x\n", (UINT32)(FPTR)blktofree))

	if(blktofree == nullptr)
	{
		return;
	}

	for (i = 0; i < 200; i++)
	{
		if (&blocks[i] == blktofree)
		{
			CDROM_LOG(("CD: freeing block %d\n", i))
		}
	}

	blktofree->size = -1;
	freeblocks++;
	buffull = 0;
	hirqreg &= ~BFUL;
}

void saturn_state::cd_getsectoroffsetnum(UINT32 bufnum, UINT32 *sectoffs, UINT32 *sectnum)
{
	if (*sectoffs == 0xffff)
	{
		// last sector
		printf("CD: Don't know how to handle offset ffff\n");
	}
	else if (*sectnum == 0xffff)
	{
		*sectnum = partitions[bufnum].numblks - *sectoffs;
	}
}

void saturn_state::cd_defragblocks(partitionT *part)
{
	UINT32 i, j;
	blockT *temp;
	UINT8 temp2;

	for (i = 0; i < (MAX_BLOCKS-1); i++)
	{
		for (j = i+1; j < MAX_BLOCKS; j++)
		{
			if ((part->blocks[i] == (blockT *)nullptr) && (part->blocks[j] != (blockT *)nullptr))
			{
				temp = part->blocks[i];
				part->blocks[i] = part->blocks[j];
				part->blocks[j] = temp;

				temp2 = part->bnum[i];
				part->bnum[i] = part->bnum[j];
				part->bnum[j] = temp2;
			}
		}
	}
}

UINT16 saturn_state::cd_readWord(UINT32 addr)
{
	UINT16 rv;

	switch (addr & 0xffff)
	{
		case 0x0008:    // read HIRQ register
		case 0x000a:
		case 0x8008:
		case 0x800a:
			rv = hirqreg;

			rv &= ~DCHG;    // always clear bit 6 (tray open)

			if (buffull) rv |= BFUL; else rv &= ~BFUL;
			if (sectorstore) rv |= CSCT; else rv &= ~CSCT;

			hirqreg = rv;

//          CDROM_LOG(("RW HIRQ: %04x\n", rv))

			return rv;

		case 0x000c:
		case 0x000e:
		case 0x800c:
		case 0x800e:
//          CDROM_LOG(("RW HIRM: %04x\n", hirqmask))
			printf("RW HIRM: %04x\n", hirqmask);
			return hirqmask;

		case 0x0018:
		case 0x001a:
		case 0x8018:
		case 0x801a:
//          CDROM_LOG(("RW CR1: %04x\n", cr1))
			return cr1;

		case 0x001c:
		case 0x001e:
		case 0x801c:
		case 0x801e:
//          CDROM_LOG(("RW CR2: %04x\n", cr2))
			return cr2;

		case 0x0020:
		case 0x0022:
		case 0x8020:
		case 0x8022:
//          CDROM_LOG(("RW CR3: %04x\n", cr3))
			return cr3;

		case 0x0024:
		case 0x0026:
		case 0x8024:
		case 0x8026:
//          CDROM_LOG(("RW CR4: %04x\n", cr4))
			//popmessage("%04x %04x %04x %04x",cr1,cr2,cr3,cr4);
			cmd_pending = 0;
			cd_stat |= CD_STAT_PERI;
			return cr4;

		case 0x8000:
			rv = 0xffff;
			switch (xfertype)
			{
				case XFERTYPE_TOC:
					rv = tocbuf[xfercount]<<8 | tocbuf[xfercount+1];

					xfercount += 2;
					xferdnum += 2;

					if (xfercount > 102*4)
					{
						xfercount = 0;
						xfertype = XFERTYPE_INVALID;
					}
					break;

				case XFERTYPE_FILEINFO_1:
					rv = finfbuf[xfercount]<<8 | finfbuf[xfercount+1];
					xfercount += 2;
					xferdnum += 2;

					if (xfercount > 6*2)
					{
						xfercount = 0;
						xfertype = XFERTYPE_INVALID;
					}
					break;

				case XFERTYPE_FILEINFO_254: // Lunar 2
					if((xfercount % (6 * 2)) == 0)
					{
						UINT32 temp = 2 + (xfercount / (0x6 * 2));

						// first 4 bytes = FAD
						finfbuf[0] = (curdir[temp].firstfad>>24)&0xff;
						finfbuf[1] = (curdir[temp].firstfad>>16)&0xff;
						finfbuf[2] = (curdir[temp].firstfad>>8)&0xff;
						finfbuf[3] = (curdir[temp].firstfad&0xff);
						// second 4 bytes = length of file
						finfbuf[4] = (curdir[temp].length>>24)&0xff;
						finfbuf[5] = (curdir[temp].length>>16)&0xff;
						finfbuf[6] = (curdir[temp].length>>8)&0xff;
						finfbuf[7] = (curdir[temp].length&0xff);
						finfbuf[8] = curdir[temp].interleave_gap_size;
						finfbuf[9] = curdir[temp].file_unit_size;
						finfbuf[10] = temp;
						finfbuf[11] = curdir[temp].flags;
					}

					rv = finfbuf[xfercount % (6 * 2)]<<8 | finfbuf[(xfercount % (6 * 2)) +1];

					xfercount += 2;
					xferdnum += 2;

					if (xfercount > (254 * 6 * 2))
					{
						xfercount = 0;
						xfertype = XFERTYPE_INVALID;
					}
					break;

				case XFERTYPE_SUBQ:
					rv = subqbuf[xfercount]<<8 | subqbuf[xfercount+1];

					xfercount += 2;
					xferdnum += 2;

					if (xfercount > 5*2)
					{
						xfercount = 0;
						xfertype = XFERTYPE_INVALID;
					}
					break;


				case XFERTYPE_SUBRW:
					rv = subrwbuf[xfercount]<<8 | subrwbuf[xfercount+1];

					xfercount += 2;
					xferdnum += 2;

					if (xfercount > 12*2)
					{
						xfercount = 0;
						xfertype = XFERTYPE_INVALID;
					}
					break;

				default:
					printf("STVCD: Unhandled xfer type %d\n", (int)xfertype);
					rv = 0;
					break;
			}

			return rv;

		default:
			CDROM_LOG(("CD: RW %08x\n", addr))
			return 0xffff;
	}

}

UINT32 saturn_state::cd_readLong(UINT32 addr)
{
	UINT32 rv = 0;

	switch (addr & 0xffff)
	{
		case 0x8000:
			switch (xfertype32)
			{
				case XFERTYPE32_GETSECTOR:
				case XFERTYPE32_GETDELETESECTOR:
					// make sure we have sectors left
					if (xfersect < xfersectnum)
					{
						// get next longword
						rv = (transpart->blocks[xfersectpos+xfersect]->data[xferoffs + 0]<<24) |
								(transpart->blocks[xfersectpos+xfersect]->data[xferoffs + 1]<<16) |
								(transpart->blocks[xfersectpos+xfersect]->data[xferoffs + 2]<<8)  |
								(transpart->blocks[xfersectpos+xfersect]->data[xferoffs + 3]<<0);

						xferdnum += 4;
						xferoffs += 4;

						// did we run out of sector?
						if (xferoffs >= transpart->blocks[xfersect]->size)
						{
							CDROM_LOG(("CD: finished xfer of block %d of %d\n", xfersect+1, xfersectnum))

							xferoffs = 0;
							xfersect++;
						}
					}
					else    // sectors are done, kill 'em all if we can
					{
						if (xfertype32 == XFERTYPE32_GETDELETESECTOR)
						{
							INT32 i;

							CDROM_LOG(("Killing sectors in done\n"))

							// deallocate the blocks
							for (i = xfersectpos; i < xfersectpos+xfersectnum; i++)
							{
								cd_free_block(transpart->blocks[i]);
								transpart->blocks[i] = (blockT *)nullptr;
								transpart->bnum[i] = 0xff;
							}

							// defrag what's left
							cd_defragblocks(transpart);

							// clean up our state
							transpart->size -= xferdnum;
							transpart->numblks -= xfersectnum;

							/* TODO: is this correct? */
							xfertype32 = XFERTYPE32_INVALID;
						}
					}
					break;

				default:
					printf("CD: unhandled 32-bit transfer type\n");
					break;
			}

			return rv;

		default:
			CDROM_LOG(("CD: RL %08x\n", addr))
			return 0xffff;
	}
}

void saturn_state::cd_writeLong(UINT32 addr, UINT32 data)
{
	switch (addr & 0xffff)
	{
		case 0x8000:
			switch (xfertype32)
			{
				case XFERTYPE32_PUTSECTOR:
					// make sure we have sectors left
					if (xfersect < xfersectnum)
					{
						// get next longword
						transpart->blocks[xfersectpos+xfersect]->data[xferoffs + 0] = (data >> 24) & 0xff;
						transpart->blocks[xfersectpos+xfersect]->data[xferoffs + 1] = (data >> 16) & 0xff;
						transpart->blocks[xfersectpos+xfersect]->data[xferoffs + 2] = (data >> 8) & 0xff;
						transpart->blocks[xfersectpos+xfersect]->data[xferoffs + 3] = (data >> 0) & 0xff;

						xferdnum += 4;
						xferoffs += 4;

						// did we run out of sector?
						if (xferoffs >= transpart->blocks[xfersectpos+xfersect]->size)
						{
							CDROM_LOG(("CD: finished xfer of block %d of %d\n", xfersect+1, xfersectnum))

							xferoffs = 0;
							xfersect++;
						}
					}
					else    // sectors are done
					{
						/* Virtual On doesnt want this to be resetted. */
						//xfertype32 = XFERTYPE32_INVALID;
					}
					break;

				default:
					printf("CD: unhandled 32-bit transfer type write\n");
					break;
			}
			break;

		default:
			break;
	}
}

void saturn_state::cd_writeWord(UINT32 addr, UINT16 data)
{
	switch(addr & 0xffff)
	{
	case 0x0008:
	case 0x000a:
	case 0x8008:
	case 0x800a:
//      CDROM_LOG(("%s:WW HIRQ: %04x & %04x => %04x\n", machine().describe_context(), hirqreg, data, hirqreg & data))
		hirqreg &= data;
		return;
	case 0x000c:
	case 0x000e:
	case 0x800c:
	case 0x800e:
//      CDROM_LOG(("WW HIRM: %04x => %04x\n", hirqmask, data))
		printf("WW HIRM: %04x => %04x\n", hirqmask, data);
		hirqmask = data;
		return;
	case 0x0018:
	case 0x001a:
	case 0x8018:
	case 0x801a:
//      CDROM_LOG(("WW CR1: %04x\n", data))
		cr1 = data;
		cd_stat &= ~CD_STAT_PERI;
		cmd_pending |= 1;
		sh1_timer->adjust(attotime::never);
		break;
	case 0x001c:
	case 0x001e:
	case 0x801c:
	case 0x801e:
//      CDROM_LOG(("WW CR2: %04x\n", data))
		cr2 = data;
		cmd_pending |= 2;
		break;
	case 0x0020:
	case 0x0022:
	case 0x8020:
	case 0x8022:
//      CDROM_LOG(("WW CR3: %04x\n", data))
		cr3 = data;
		cmd_pending |= 4;
		break;
	case 0x0024:
	case 0x0026:
	case 0x8024:
	case 0x8026:
//      CDROM_LOG(("WW CR4: %04x\n", data))
		cr4 = data;
		cmd_pending |= 8;
		sh1_timer->adjust(attotime::from_hz(get_timing_command()));
		break;
	default:
		CDROM_LOG(("CD: WW %08x %04x\n", addr, data))
		break;
	}
}

READ32_MEMBER( saturn_state::stvcd_r )
{
	UINT32 rv = 0;

	offset <<= 2;

	switch (offset)
	{
		case 0x88008:
		case 0x8800a:
		case 0x8800c:
		case 0x8800e:
		case 0x88018:
		case 0x8801a:
		case 0x8801c:
		case 0x8801e:
		case 0x88020:
		case 0x88022:
		case 0x88024:
		case 0x88026:
		case 0x90008:
		case 0x9000a:
		case 0x9000c:
		case 0x9000e:
		case 0x90018:
		case 0x9001a:
		case 0x9001c:
		case 0x9001e:
		case 0x90020:
		case 0x90022:
		case 0x90024:
		case 0x90026:
			rv = cd_readWord(offset);
			return rv<<16;

		case 0x98000:
		case 0x18000:
			if (mem_mask == 0xffffffff)
			{
				rv = cd_readLong(offset);
			}
			else if (mem_mask == 0xffff0000)
			{
				rv = cd_readWord(offset)<<16;
			}
			else if (mem_mask == 0x0000ffff)
			{
				rv = cd_readWord(offset);
			}
			else
			{
				osd_printf_error("CD: Unknown data buffer read @ mask = %08x\n", mem_mask);
			}

			break;

		default:
			printf("Unknown CD read %x\n", offset);
			break;
	}

	return rv;
}

WRITE32_MEMBER( saturn_state::stvcd_w )
{
	offset <<= 2;

	switch (offset)
	{
		case 0x18000:
			if (mem_mask == 0xffffffff)
				cd_writeLong(offset, data);
			else
				printf("CD: Unknown data buffer write @ mask = %08x\n", mem_mask);
			break;

		case 0x88008:
		case 0x8800a:
		case 0x8800c:
		case 0x8800e:
		case 0x88018:
		case 0x8801a:
		case 0x8801c:
		case 0x8801e:
		case 0x88020:
		case 0x88022:
		case 0x88024:
		case 0x88026:
		case 0x90008:
		case 0x9000a:
		case 0x9000c:
		case 0x9000e:
		case 0x90018:
		case 0x9001a:
		case 0x9001c:
		case 0x9001e:
		case 0x90020:
		case 0x90022:
		case 0x90024:
		case 0x90026:
			cd_writeWord(offset, data>>16);
			break;

		default:
			printf("Unknown CD write %x @ %x\n", data, offset);
			//xferdnum = 0x8c00;
			break;
	}
}

// iso9660 parsing
void saturn_state::read_new_dir(UINT32 fileno)
{
	int foundpd, i;
	UINT32 cfad;//, dirfad;
	UINT8 sect[2048];

	if (fileno == 0xffffff)
	{
		cfad = 166;     // first sector of directory as per iso9660 specs

		foundpd = 0;    // search for primary vol. desc
		while ((!foundpd) && (cfad < 200))
		{
			if(sectlenin != 2048)
				popmessage("Sector Length %d, contact MAMEdev (0)",sectlenin);

			memset(sect, 0, 2048);
			cd_readblock(cfad++, sect);

			if ((sect[1] == 'C') && (sect[2] == 'D') && (sect[3] == '0') && (sect[4] == '0') && (sect[5] == '1'))
			{
				switch (sect[0])
				{
					case 0: // boot record
						break;

					case 1: // primary vol. desc
						foundpd = 1;
						break;

					case 2: // secondary vol desc
						break;

					case 3: // vol. section descriptor
						break;

					case 0xff:
						cfad = 200;
						break;
				}
			}
		}

		// got primary vol. desc.
		if (foundpd)
		{
			//dirfad = sect[140] | (sect[141]<<8) | (sect[142]<<16) | (sect[143]<<24);
			//dirfad += 150;

			// parse root entry
			curroot.firstfad = sect[158] | (sect[159]<<8) | (sect[160]<<16) | (sect[161]<<24);
			curroot.firstfad += 150;
			curroot.length = sect[166] | (sect[167]<<8) | (sect[168]<<16) | (sect[169]<<24);
			curroot.flags = sect[181];
			for (i = 0; i < sect[188]; i++)
			{
				curroot.name[i] = sect[189+i];
			}
			curroot.name[i] = '\0'; // terminate

			// easy to fix, but make sure we *need* to first
			if (curroot.length > MAX_DIR_SIZE)
			{
				osd_printf_error("ERROR: root directory too big (%d)\n", curroot.length);
			}

			// done with all that, read the root directory now
			make_dir_current(curroot.firstfad);
		}
	}
	else
	{
		if (curdir[fileno].length > MAX_DIR_SIZE)
		{
			osd_printf_error("ERROR: new directory too big (%d)!\n", curdir[fileno].length);
		}
		make_dir_current(curdir[fileno].firstfad);
	}
}

// makes the directory pointed to by FAD current
void saturn_state::make_dir_current(UINT32 fad)
{
	int i;
	UINT32 nextent, numentries;
	dynamic_buffer sect(MAX_DIR_SIZE);
	direntryT *curentry;

	memset(&sect[0], 0, MAX_DIR_SIZE);
	if(sectlenin != 2048)
		popmessage("Sector Length %d, contact MAMEdev (1)",sectlenin);

	for (i = 0; i < (curroot.length/2048); i++)
	{
		cd_readblock(fad+i, &sect[2048*i]);
	}

	nextent = 0;
	numentries = 0;
	while (nextent < MAX_DIR_SIZE)
	{
		if (sect[nextent])
		{
			nextent += sect[nextent];
			numentries++;
		}
		else
		{
			nextent = MAX_DIR_SIZE;
		}
	}

	curdir.resize(numentries);
	curentry = &curdir[0];
	numfiles = numentries;

	nextent = 0;
	while (numentries)
	{
		// [0] record size
		// [1] xa record size
		// [2-5] lba
		// [6-9] (lba?)
		// [10-13] size
		// [14-17] (size?)
		// [18] year
		// [19] month
		// [20] day
		// [21] hour
		// [22] minute
		// [23] second
		// [24] gmt offset
		// [25] flags
		// [26] file unit size
		// [27] interleave gap size
		// [28-29] volume sequencer number
		// [30-31] (volume sequencer number?)
		// [32] name character size
		// [33+ ...] file name

		curentry->record_size = sect[nextent+0];
		curentry->xa_record_size = sect[nextent+1];
		curentry->firstfad = sect[nextent+2] | (sect[nextent+3]<<8) | (sect[nextent+4]<<16) | (sect[nextent+5]<<24);
		curentry->firstfad += 150;
		curentry->length = sect[nextent+10] | (sect[nextent+11]<<8) | (sect[nextent+12]<<16) | (sect[nextent+13]<<24);
		curentry->year = sect[nextent+18];
		curentry->month = sect[nextent+19];
		curentry->day = sect[nextent+20];
		curentry->hour = sect[nextent+21];
		curentry->minute = sect[nextent+22];
		curentry->second = sect[nextent+23];
		curentry->gmt_offset = sect[nextent+24];
		curentry->flags = sect[nextent+25];
		curentry->file_unit_size = sect[nextent+26];
		curentry->interleave_gap_size = sect[nextent+27];
		curentry->volume_sequencer_number = sect[nextent+28] | (sect[nextent+29] << 8);

		for (i = 0; i < sect[nextent+32]; i++)
		{
			curentry->name[i] = sect[nextent+33+i];
		}
		curentry->name[i] = '\0';   // terminate
		//printf("%08x %08x %s %d/%d/%d\n",curentry->firstfad,curentry->length,curentry->name,curentry->year,curentry->month,curentry->day);

		nextent += sect[nextent];
		curentry++;
		numentries--;
	}

	for (i = 0; i < numfiles; i++)
	{
		if (!(curdir[i].flags & 0x02))
		{
			firstfile = i;
			i = numfiles;
		}
	}
}

void saturn_state::stvcd_exit( void )
{
	curdir.clear();

	if (cdrom)
	{
		cdrom_image_device *cddevice = machine().device<cdrom_image_device>("cdrom");
		if (cddevice==nullptr)
		{
			cdrom_close(cdrom);
		}
		cdrom = (cdrom_file *)nullptr;
	}
}

void saturn_state::cd_readTOC(void)
{
	int i, ntrks, tocptr, fad;

	xfertype = XFERTYPE_TOC;
	xfercount = 0;

	if (cdrom)
	{
		ntrks = cdrom_get_last_track(cdrom);
	}
	else
	{
		ntrks = 0;
	}

	// data format for Saturn TOC:
	// no header.
	// 4 bytes per track
	// top nibble of first byte is CTRL info
	// low nibble is ADR
	// next 3 bytes are FAD address (LBA + 150)
	// there are always 99 track entries (0-98)
	// unused tracks are ffffffff.
	// entries 99-101 are metadata

	tocptr = 0; // starting point of toc entries

	for (i = 0; i < ntrks; i++)
	{
		if (cdrom)
		{
			//tocbuf[tocptr] = sega_cdrom_get_adr_control(cdrom, i);
			//HACK: ddsom does not enter ingame with the line above!
			tocbuf[tocptr] = cdrom_get_adr_control(cdrom, i)<<4 | 0x01;
		}
		else
		{
			tocbuf[tocptr] = 0xff;
		}

		if (cdrom)
		{
			fad = cdrom_get_track_start(cdrom, i) + 150;

			tocbuf[tocptr+1] = (fad>>16)&0xff;
			tocbuf[tocptr+2] = (fad>>8)&0xff;
			tocbuf[tocptr+3] = fad&0xff;
		}
		else
		{
			tocbuf[tocptr+1] = 0xff;
			tocbuf[tocptr+2] = 0xff;
			tocbuf[tocptr+3] = 0xff;
		}

		tocptr += 4;
	}

	// fill in the rest
	for ( ; i < 99; i++)
	{
		tocbuf[tocptr] = 0xff;
		tocbuf[tocptr+1] = 0xff;
		tocbuf[tocptr+2] = 0xff;
		tocbuf[tocptr+3] = 0xff;

		tocptr += 4;
	}

	// tracks 99-101 are special metadata
	// $$$FIXME: what to do with the address info for these?
	tocptr = 99 * 4;
	tocbuf[tocptr] = tocbuf[0]; // get ctrl/adr from first track
	tocbuf[tocptr+1] = 1;   // first track's track #
	tocbuf[tocptr+2] = 0;
	tocbuf[tocptr+3] = 0;

	tocbuf[tocptr+4] = tocbuf[(ntrks-1)*4]; // ditto for last track
	tocbuf[tocptr+5] = ntrks;   // last track's track #
	tocbuf[tocptr+6] = 0;
	tocbuf[tocptr+7] = 0;

	// get total disc length (start of lead-out)
	fad = cdrom_get_track_start(cdrom, 0xaa) + 150;

	tocbuf[tocptr+8] = tocbuf[0];
	tocbuf[tocptr+9]  = (fad>>16)&0xff;
	tocbuf[tocptr+10] = (fad>>8)&0xff;
	tocbuf[tocptr+11] = fad&0xff;
}

saturn_state::partitionT *saturn_state::cd_filterdata(filterT *flt, int trktype, UINT8 *p_ok)
{
	int match, keepgoing;
	partitionT *filterprt;

	CDROM_LOG(("cd_filterdata, trktype %d\n", trktype))
	match = 1;
	keepgoing = 2;
	lastbuf = flt->condtrue;

	// loop on the filters
	do
	{
		// FAD range check?
		/* according to an obscure document note, this switches the filter connector to be false if the range fails ... I think ... */
		if (flt->mode & 0x40)
		{
			if ((cd_curfad < flt->fad) || (cd_curfad > (flt->fad + flt->range)))
			{
				printf("curfad reject %08x %08x %08x %08x\n",cd_curfad,fadstoplay,flt->fad,flt->fad+flt->range);
				match = 0;
				//lastbuf = flt->condfalse;
				//flt = &filters[lastbuf];
			}
		}

		if ((trktype != CD_TRACK_AUDIO) && (curblock.data[15] == 2))
		{
			if (flt->mode & 1)  // file number
			{
				if (curblock.fnum != flt->fid)
				{
					printf("fnum reject\n");
					match = 0;
				}
			}

			if (flt->mode & 2)  // channel number
			{
				if (curblock.chan != flt->chan)
				{
					printf("channel number reject\n");
					match = 0;
				}
			}

			if (flt->mode & 4)  // sub mode
			{
				if((curblock.subm & flt->smmask) != flt->smval)
				{
					printf("sub mode reject\n");
					match = 0;
				}
			}

			if (flt->mode & 8)  // coding information
			{
				if((curblock.cinf & flt->cimask) != flt->cival)
				{
					printf("coding information reject\n");
					match = 0;
				}
			}

			if (flt->mode & 0x10)   // reverse subheader conditions
			{
				match ^= 1;
			}
		}

		if (match)
		{
			//lastbuf = flt->condtrue;
			//filterprt = &partitions[lastbuf];
			// we're done
			keepgoing = 0;
		}
		else
		{
			lastbuf = flt->condfalse;

			// reject sector if no match on either connector
			if ((lastbuf == 0xff) || (keepgoing == 0))
			{
				*p_ok = 0;
				return (partitionT *)nullptr;
			}

			// try again using the filter that was on the "false" connector
			flt = &filters[lastbuf];
			match = 1;

			// and exit if we fail
			keepgoing--;
		}
	} while (keepgoing);

	filterprt = &partitions[lastbuf];

	// try to allocate a block
	filterprt->blocks[filterprt->numblks] = cd_alloc_block(&filterprt->bnum[filterprt->numblks]);

	// did the allocation succeed?
	if (filterprt->blocks[filterprt->numblks] == (blockT *)nullptr)
	{
		*p_ok = 0;
		return (partitionT *)nullptr;
	}

	// copy working block to the newly allocated one
	memcpy(filterprt->blocks[filterprt->numblks], &curblock, sizeof(blockT));

	// and massage the data format a bit
	switch  (curblock.size)
	{
		case 2048:  // user data
			if (curblock.data[15] == 2)
			{
				// mode 2
				memcpy(&filterprt->blocks[filterprt->numblks]->data[0], &curblock.data[24], curblock.size);
			}
			else
			{
				// mode 1
				memcpy(&filterprt->blocks[filterprt->numblks]->data[0], &curblock.data[16], curblock.size);
			}
			break;

		case 2324:  // Mode 2 Form 2 data
			memcpy(&filterprt->blocks[filterprt->numblks]->data[0], &curblock.data[24], curblock.size);
			break;

		case 2336:  // Mode 2 Form 2 skip sync/header
			memcpy(&filterprt->blocks[filterprt->numblks]->data[0], &curblock.data[16], curblock.size);
			break;

		case 2340:  // Mode 2 Form 2 skip sync only
			memcpy(&filterprt->blocks[filterprt->numblks]->data[0], &curblock.data[12], curblock.size);
			break;

		case 2352:  // want all data, it's already done, so don't do it again :)
			break;
	}

	// update the status of the partition
	if (filterprt->size == -1)
		filterprt->size = 0;

	filterprt->size += filterprt->blocks[filterprt->numblks]->size;
	filterprt->numblks++;

	*p_ok = 1;
	return filterprt;
}

// read a single sector off the CD, applying the current filter(s) as necessary
saturn_state::partitionT *saturn_state::cd_read_filtered_sector(INT32 fad, UINT8 *p_ok)
{
	int trktype;

	if ((cddevice != nullptr) && (!buffull))
	{
		// find out the track's type
		trktype = cdrom_get_track_type(cdrom, cdrom_get_track(cdrom, fad-150));

		// now get a raw 2352 byte sector - if it's mode 1, get mode1_raw
		if ((trktype == CD_TRACK_MODE1) || (trktype == CD_TRACK_MODE1_RAW))
		{
			cdrom_read_data(cdrom, fad-150, curblock.data, CD_TRACK_MODE1_RAW);
		}
		else if (trktype != CD_TRACK_AUDIO) // if not audio it must be mode 2 so get mode2_raw
		{
			cdrom_read_data(cdrom, fad-150, curblock.data, CD_TRACK_MODE2_RAW);
		}
		else
		{
			cdrom_read_data(cdrom, fad-150, curblock.data, CD_TRACK_AUDIO);
		}

		curblock.size = sectlenin;
		curblock.FAD = fad;

		// if track is Mode 2, get the subheader values
		if ((trktype != CD_TRACK_AUDIO) && (curblock.data[15] == 2))
		{
			curblock.chan = curblock.data[17];
			curblock.fnum = curblock.data[16];
			curblock.subm = curblock.data[18];
			curblock.cinf = curblock.data[19];

			// if it's Form 2, the length is actually 2324 bytes
			if (curblock.subm & 0x20)
			{
				curblock.size = 2324;
			}
		}

		return cd_filterdata(cddevice, trktype, &*p_ok);
	}

	*p_ok = 0;
	return (partitionT *)nullptr;
}

// loads in data set up by a CD-block PLAY command
void saturn_state::cd_playdata( void )
{
	if ((cd_stat & 0x0f00) == CD_STAT_SEEK)
	{
		INT32 fad_diff;
		//printf("PRE %08x %08x %08x %d\n",cd_curfad,cd_fad_seek,cd_stat,cd_fad_seek - cd_curfad);

		fad_diff = (cd_fad_seek - cd_curfad);

		/* Zero Divide wants this TODO: timings. */
		if(fad_diff > (750*cd_speed))
		{
			//printf("PRE FFWD %08x %08x %08x %d %d\n",cd_curfad,cd_fad_seek,cd_stat,cd_fad_seek - cd_curfad,750*cd_speed);
			cd_curfad += (750*cd_speed);
			//printf("POST FFWD %08x %08x %08x %d %d\n",cd_curfad,cd_fad_seek,cd_stat,cd_fad_seek - cd_curfad, 750*cd_speed);
		}
		else if(fad_diff < (-750*cd_speed))
		{
			//printf("PRE REW %08x %08x %08x %d %d\n",cd_curfad,cd_fad_seek,cd_stat,cd_fad_seek - cd_curfad, -750*cd_speed);
			cd_curfad -= (750*cd_speed);
			//printf("POST REW %08x %08x %08x %d %d\n",cd_curfad,cd_fad_seek,cd_stat,cd_fad_seek - cd_curfad, -750*cd_speed);
		}
		else
		{
			//printf("Ready\n");
			cd_curfad = cd_fad_seek;
			cd_stat = CD_STAT_PLAY;
		}

		return;
	}

	if ((cd_stat & 0x0f00) == CD_STAT_PLAY)
	{
		if (fadstoplay)
		{
			logerror("STVCD: Reading FAD %d\n", cd_curfad);

			if (cdrom)
			{
				UINT8 p_ok;

				if(cdrom_get_track_type(cdrom, cdrom_get_track(cdrom, cd_curfad)) != CD_TRACK_AUDIO)
				{
					cd_read_filtered_sector(cd_curfad,&p_ok);
					machine().device<cdda_device>("cdda")->stop_audio(); //stop any pending CD-DA
				}
				else
				{
					p_ok = 1; // TODO
					machine().device<cdda_device>("cdda")->start_audio(cd_curfad, 1);
				}

				if(p_ok)
				{
					cd_curfad++;
					fadstoplay--;
					hirqreg |= CSCT;
					sectorstore = 1;

					if (!fadstoplay)
					{
						if(cdda_repeat_count >= cdda_maxrepeat)
						{
							CDROM_LOG(("cd_playdata: playback ended\n"))
							cd_stat = CD_STAT_PAUSE;

							hirqreg |= PEND;

							if (playtype == 1)
							{
								CDROM_LOG(("cd_playdata: setting EFLS\n"))
								hirqreg |= EFLS;
							}
						}
						else
						{
							if(cdda_repeat_count < 0xe)
								cdda_repeat_count++;

							cd_curfad = cdrom_get_track_start(cdrom, cur_track-1) + 150;
							fadstoplay = cdrom_get_track_start(cdrom, cur_track) - cd_curfad;
						}
					}
				}
			}
		}
	}
}

// loads a single sector off the CD, anywhere from FAD 150 on up
void saturn_state::cd_readblock(UINT32 fad, UINT8 *dat)
{
	if (cdrom)
	{
		cdrom_read_data(cdrom, fad-150, dat, CD_TRACK_MODE1);
	}
}

void saturn_state::stvcd_set_tray_open( void )
{
	if(!tray_is_closed)
		return;

	hirqreg |= DCHG;
	cd_stat = CD_STAT_OPEN;

	cdrom = (cdrom_file *)nullptr;
	tray_is_closed = 0;

	popmessage("Tray Open");
}

void saturn_state::stvcd_set_tray_close( void )
{
	/* avoid user attempts to load a CD-ROM without opening the tray first (emulation asserts anyway with current framework) */
	if(tray_is_closed)
		return;

	hirqreg |= DCHG;

	cdrom_image_device *cddevice = machine().device<cdrom_image_device>("cdrom");
	if (cddevice!=nullptr)
	{
		// MESS case
		cdrom = cddevice->get_cdrom_file();
	}
	else
	{
		// MAME case
		cdrom = cdrom_open(machine().rom_load().get_disk_handle("cdrom"));
	}

	machine().device<cdda_device>("cdda")->set_cdrom(cdrom);

	if (cdrom)
	{
		CDROM_LOG(("Opened CD-ROM successfully, reading root directory\n"))
		//read_new_dir(0xffffff);  // read root directory
		cd_stat = CD_STAT_PAUSE;
	}
	else
	{
		cd_stat = CD_STAT_NODISC;
	}

	cd_speed = 2;
	cdda_repeat_count = 0;
	tray_is_closed = 1;

	popmessage("Tray Close");
}
