// license:BSD-3-Clause
// copyright-holders:Olivier Galibert
/*********************************************************************

    formats/dsk_dsk.c

    DSK disk images

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

#include <string.h>
#include <assert.h>

#include "imageutl.h"
#include "flopimg.h"

#define MV_CPC      "MV - CPC"
#define EXTENDED    "EXTENDED"

struct dskdsk_tag
{
	int disk_image_type;  /* image type: standard or extended */
	int heads;
	int tracks;
	int sector_size;
	UINT64 track_offsets[84*2]; /* offset within data for each track */

};


static struct dskdsk_tag *get_tag(floppy_image_legacy *floppy)
{
	struct dskdsk_tag *tag;
	tag = (dskdsk_tag *)floppy_tag(floppy);
	return tag;
}



FLOPPY_IDENTIFY( dsk_dsk_identify )
{
	UINT8 header[8];

	floppy_image_read(floppy, header, 0, 8);
	if ( memcmp( header, MV_CPC, 8 ) ==0) {
		*vote = 100;
	} else
	if ( memcmp( header, EXTENDED, 8 ) ==0) {
		*vote = 100;
	} else {
		*vote = 0;
	}
	return FLOPPY_ERROR_SUCCESS;
}

static int dsk_get_heads_per_disk(floppy_image_legacy *floppy)
{
	return get_tag(floppy)->heads;
}

static int dsk_get_tracks_per_disk(floppy_image_legacy *floppy)
{
	return get_tag(floppy)->tracks;
}

static UINT64 dsk_get_track_offset(floppy_image_legacy *floppy, int head, int track)
{
	return get_tag(floppy)->track_offsets[(track<<1) + head];
}

static floperr_t get_offset(floppy_image_legacy *floppy, int head, int track, int sector, int sector_is_index, UINT64 *offset)
{
	UINT64 offs;
	UINT64 track_offset;
	UINT8 track_info[0x100];
	UINT8 sectors_per_track;
	int i;
	/* translate the sector to a raw sector */

	/* check to see if we are out of range */
	if ((head < 0) || (head >= get_tag(floppy)->heads) || (track < 0) || (track >= get_tag(floppy)->tracks)
			|| (sector < 0) )
		return FLOPPY_ERROR_SEEKERROR;

	track_offset = dsk_get_track_offset(floppy, head, track);

	floppy_image_read(floppy, track_info, track_offset, 0x100);

	sectors_per_track = track_info[0x015];
	if (!sector_is_index) {
		if (sector >= sectors_per_track) {
			return FLOPPY_ERROR_SEEKERROR;
		}
	}

	if (get_tag(floppy)->disk_image_type==0) {
		get_tag(floppy)->sector_size = (1<<(track_info[0x014]+7));
		offs = track_offset + 0x100 +sector * get_tag(floppy)->sector_size;
	} else {
		get_tag(floppy)->sector_size = track_info[0x18 + (sector<<3) + 6] + (track_info[0x18+(sector<<3) + 7]<<8);
		offs = track_offset + 0x100;
		for (i=0;i<sector;i++) {
			offs += track_info[0x18 + (i<<3) + 6] + (track_info[0x18+(i<<3) + 7]<<8);
		}
	}

	if (offset)
		*offset = offs;
	return FLOPPY_ERROR_SUCCESS;
}



static floperr_t internal_dsk_read_sector(floppy_image_legacy *floppy, int head, int track, int sector, int sector_is_index, void *buffer, size_t buflen)
{
	UINT64 offset;
	floperr_t err;
	err = get_offset(floppy, head, track, sector, sector_is_index, &offset);
	if (err)
		return err;
	floppy_image_read(floppy, buffer, offset, buflen);
	return FLOPPY_ERROR_SUCCESS;
}



static floperr_t internal_dsk_write_sector(floppy_image_legacy *floppy, int head, int track, int sector, int sector_is_index, const void *buffer, size_t buflen, int ddam)
{
	UINT64 offset;
	floperr_t err;

	err = get_offset(floppy, head, track, sector, sector_is_index, &offset);
	if (err)
		return err;

	floppy_image_write(floppy, buffer, offset, buflen);
	return FLOPPY_ERROR_SUCCESS;
}



static floperr_t dsk_read_sector(floppy_image_legacy *floppy, int head, int track, int sector, void *buffer, size_t buflen)
{
	return internal_dsk_read_sector(floppy, head, track, sector, FALSE, buffer, buflen);
}

static floperr_t dsk_write_sector(floppy_image_legacy *floppy, int head, int track, int sector, const void *buffer, size_t buflen, int ddam)
{
	return internal_dsk_write_sector(floppy, head, track, sector, FALSE, buffer, buflen, ddam);
}

static floperr_t dsk_read_indexed_sector(floppy_image_legacy *floppy, int head, int track, int sector, void *buffer, size_t buflen)
{
	return internal_dsk_read_sector(floppy, head, track, sector, TRUE, buffer, buflen);
}

static floperr_t dsk_write_indexed_sector(floppy_image_legacy *floppy, int head, int track, int sector, const void *buffer, size_t buflen, int ddam)
{
	return internal_dsk_write_sector(floppy, head, track, sector, TRUE, buffer, buflen, ddam);
}

static floperr_t dsk_get_sector_length(floppy_image_legacy *floppy, int head, int track, int sector, UINT32 *sector_length)
{
	floperr_t err;
	err = get_offset(floppy, head, track, sector, FALSE, nullptr);
	if (err)
		return err;

	if (sector_length) {
		*sector_length = get_tag(floppy)->sector_size;
	}
	return FLOPPY_ERROR_SUCCESS;
}

static floperr_t dsk_get_indexed_sector_info(floppy_image_legacy *floppy, int head, int track, int sector_index, int *cylinder, int *side, int *sector, UINT32 *sector_length, unsigned long *flags)
{
	floperr_t retVal;
	UINT64 offset;
	UINT8 sector_info[0x100];
	int pos;

	retVal = get_offset(floppy, head, track, sector_index, FALSE, nullptr);
	offset = dsk_get_track_offset(floppy,head,track);
	pos = 0x18 + (sector_index << 3);
	floppy_image_read(floppy, sector_info, offset, 0x100);
	if (cylinder)
		*cylinder = sector_info[pos + 0];
	if (side)
		*side = sector_info[pos + 1];
	if (sector)
		*sector = sector_info[pos + 2];
	if (sector_length) {
		*sector_length = 1 << (sector_info[pos + 3] + 7);
	}
	if (flags)
		*flags = (sector_info[pos + 5] & 0x40) ? ID_FLAG_DELETED_DATA : 0;
	return retVal;
}


FLOPPY_CONSTRUCT( dsk_dsk_construct )
{
	struct FloppyCallbacks *callbacks;
	struct dskdsk_tag *tag;
	UINT8 header[0x100];
	UINT64 tmp = 0;
	int i;
	int skip,cnt;

	if(params)
	{
		// create
		return FLOPPY_ERROR_UNSUPPORTED;
	}

	floppy_image_read(floppy, header, 0, 0x100);
#ifdef SPOT_DUPLICATES
	// this allow to spot .dsk files with same data and different headers, making easier to debug softlists.
	UINT32 temp_size = floppy_image_size(floppy);
	UINT8 tmp_copy[temp_size - 0x100];
	floppy_image_read(floppy,tmp_copy,0x100,temp_size - 0x100);
	printf("CRC16: %d\n", ccitt_crc16(0xffff, tmp_copy, temp_size - 0x100));
#endif

	tag = (struct dskdsk_tag *) floppy_create_tag(floppy, sizeof(struct dskdsk_tag));
	if (!tag)
		return FLOPPY_ERROR_OUTOFMEMORY;

	tag->heads   = header[0x31];
	if (tag->heads==1) {
		skip = 2;
	} else {
		skip = 1;
	}
	tag->tracks  = header[0x30];
	cnt =0;
	if ( memcmp( header, MV_CPC, 8 ) ==0) {
		tag->disk_image_type = 0;
		tmp = 0x100;
		for (i=0; i<tag->tracks * tag->heads; i++)
		{
			tag->track_offsets[cnt] = tmp;
			tmp += pick_integer_le(header, 0x32, 2);
			cnt += skip;
		}
	} else  {
		tag->disk_image_type = 1;
		tmp = 0x100;
		for (i=0; i<tag->tracks * tag->heads; i++)
		{
			tag->track_offsets[cnt] = tmp;
			tmp += header[0x34 + i] << 8;
			cnt += skip;
		}
	}

	callbacks = floppy_callbacks(floppy);
	callbacks->read_sector = dsk_read_sector;
	callbacks->write_sector = dsk_write_sector;
	callbacks->read_indexed_sector = dsk_read_indexed_sector;
	callbacks->write_indexed_sector = dsk_write_indexed_sector;
	callbacks->get_sector_length = dsk_get_sector_length;
	callbacks->get_heads_per_disk = dsk_get_heads_per_disk;
	callbacks->get_tracks_per_disk = dsk_get_tracks_per_disk;
	callbacks->get_indexed_sector_info = dsk_get_indexed_sector_info;
	return FLOPPY_ERROR_SUCCESS;
}

#include "dsk_dsk.h"

#define DSK_FORMAT_HEADER   "MV - CPC"
#define EXT_FORMAT_HEADER   "EXTENDED CPC DSK"

dsk_format::dsk_format() : floppy_image_format_t()
{
}

const char *dsk_format::name() const
{
	return "dsk";
}

const char *dsk_format::description() const
{
	return "CPC DSK Format";
}

const char *dsk_format::extensions() const
{
	return "dsk";
}

bool dsk_format::supports_save() const
{
	return false;
}

int dsk_format::identify(io_generic *io, UINT32 form_factor)
{
	UINT8 header[16];

	io_generic_read(io, &header, 0, sizeof(header));
	if ( memcmp( header, DSK_FORMAT_HEADER, 8 ) ==0) {
		return 100;
	}
	if ( memcmp( header, EXT_FORMAT_HEADER, 16 ) ==0) {
		return 100;
	}
	return 0;
}


#pragma pack(1)

struct track_header
{
	UINT8 headertag[13];
	UINT16 unused1;
	UINT8 unused1b;
	UINT8 track_number;
	UINT8 side_number;
	UINT8 datarate;
	UINT8 rec_mode;
	UINT8 sector_size_code;
	UINT8 number_of_sector;
	UINT8 gap3_length;
	UINT8 filler_byte;
};

struct sector_header
{
	UINT8   track;
	UINT8   side;
	UINT8   sector_id;
	UINT8   sector_size_code;
	UINT8   fdc_status_reg1;
	UINT8   fdc_status_reg2;
	UINT16  data_length;
};

#pragma pack()

bool dsk_format::load(io_generic *io, UINT32 form_factor, floppy_image *image)
{
	UINT8 header[0x100];
	bool extendformat = FALSE;

	UINT64 image_size = io_generic_size(io);

	io_generic_read(io, &header, 0, sizeof(header));
	if ( memcmp( header, EXT_FORMAT_HEADER, 16 ) ==0) {
		extendformat = TRUE;
	}

	int heads = header[0x31];
	int skip = 1;
	if (heads==1) {
		skip = 2;
	}
	int tracks  = header[0x30];
	UINT64 track_offsets[84*2];
	int cnt =0;
	if (!extendformat) {
		int tmp = 0x100;
		for (int i=0; i<tracks * heads; i++)
		{
			track_offsets[cnt] = tmp;
			tmp += pick_integer_le(header, 0x32, 2);
			cnt += skip;
		}
	} else  {
		int tmp = 0x100;
		for (int i=0; i<tracks * heads; i++)
		{
			int length = header[0x34 + i] << 8;
			if (length != 0)
			{
				track_offsets[cnt] = tmp;
				tmp += length;
			}
			else
			{
				track_offsets[cnt] = image_size;
			}

			cnt += skip;
		}
	}

	int counter = 0;
	for(int track=0; track < tracks; track++) {
		for(int side=0; side < heads; side++) {
			if(track_offsets[(track<<1)+side] >= image_size)
				continue;
			track_header tr;
			io_generic_read(io, &tr,track_offsets[(track<<1)+side],sizeof(tr));
			desc_pc_sector sects[256];
			UINT8 sect_data[65536];
			int sdatapos = 0;
			int pos = track_offsets[(track<<1)+side] + 0x100;
			for(int j=0;j<tr.number_of_sector;j++) {
				sector_header sector;
				io_generic_read(io, &sector,track_offsets[(track<<1)+side]+sizeof(tr)+(sizeof(sector)*j),sizeof(sector));

				sects[j].track       = sector.track;
				sects[j].head        = sector.side;
				sects[j].sector      = sector.sector_id;
				sects[j].size        = sector.sector_size_code;
				if(extendformat)
					sects[j].actual_size = sector.data_length;
				else
					sects[j].actual_size = 128 << tr.sector_size_code;
				sects[j].deleted     = sector.fdc_status_reg1 == 0xb2;
				sects[j].bad_crc     = sector.fdc_status_reg1 == 0xb5;

				if(!sects[j].deleted) {
					sects[j].data = sect_data + sdatapos;
					io_generic_read(io, sects[j].data, pos, sects[j].actual_size);
					sdatapos += sects[j].actual_size;

				} else
					sects[j].data = nullptr;

				if(extendformat)
					pos += sector.data_length;
				else
					pos += 128 << tr.sector_size_code;
			}
			build_pc_track_mfm(track, side, image, 100000, tr.number_of_sector, sects, tr.gap3_length);
			counter++;
		}
	}
	return true;
}

const floppy_format_type FLOPPY_DSK_FORMAT = &floppy_image_format_creator<dsk_format>;
