frodo-wii/Src/1541d64.cpp

/*
 *  1541d64.cpp - 1541 emulation in disk image files (.d64/.x64/zipcode)
 *
 *  Frodo (C) 1994-1997,2002-2005 Christian Bauer
 *  zipcode decoding routines (C) 1993-1997 Marko M<EFBFBD>kel<EFBFBD>, Paul David Doherty
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/*
 *  Incompatibilities:
 *   - No support for relative files
 *   - Unimplemented commands: P
 *   - Impossible to implement: B-E, M-E
 */

#include "sysdeps.h"

#include "1541d64.h"
#include "IEC.h"
#include "Prefs.h"
#include "C64.h"
#include "main.h"

#define DEBUG 0
#include "fdebug.h"


// Channel modes (IRC users listen up :-)
enum {
	CHMOD_FREE,			// Channel free
	CHMOD_COMMAND,		// Command/error channel
	CHMOD_DIRECTORY,	// Reading directory, using large allocated buffer
	CHMOD_FILE,			// Sequential file open, using buffer in 1541 RAM
	CHMOD_REL,			// Relative file open, using buffer in 1541 RAM
	CHMOD_DIRECT		// Direct buffer access ('#'), using buffer in 1541 RAM
};

// Directory track
const int DIR_TRACK = 18;

// BAM structure
enum {
	BAM_DIR_TRACK = 0,		// Track...
	BAM_DIR_SECTOR = 1,		// ...and sector of first directory block (unused)
	BAM_FMT_TYPE = 2,		// Format type
	BAM_BITMAP = 4,			// Sector allocation map
	BAM_DISK_NAME = 144,	// Disk name
	BAM_DISK_ID = 162,		// Disk ID
	BAM_FMT_CHAR = 165		// Format characters
};

// Directory structure
enum {
	DIR_NEXT_TRACK = 0,		// Track...
	DIR_NEXT_SECTOR = 1,	// ... and sector of next directory block
	DIR_ENTRIES = 2,		// Start of directory entries (8)

	DE_TYPE = 0,			// File type/flags
	DE_TRACK = 1,			// Track...
	DE_SECTOR = 2,			// ...and sector of first data block
	DE_NAME = 3,			// File name
	DE_SIDE_TRACK = 19,		// Track...
	DE_SIDE_SECTOR = 20,	// ...and sector of first side sector
	DE_REC_LEN = 21,		// Record length
	DE_OVR_TRACK = 26,		// Track...
	DE_OVR_SECTOR = 27,		// ...and sector on overwrite (@)
	DE_NUM_BLOCKS_L = 28,	// Number of blocks, LSB
	DE_NUM_BLOCKS_H = 29,	// Number of blocks, MSB

	SIZEOF_DE = 32			// Size of directory entry
};

// Interleave of directory and data blocks
const int DIR_INTERLEAVE = 3;
const int DATA_INTERLEAVE = 10;

// Number of sectors per track, for all tracks
const int num_sectors[41] = {
	0,
	21,21,21,21,21,21,21,21,21,21,21,21,21,21,21,21,21,
	19,19,19,19,19,19,19,
	18,18,18,18,18,18,
	17,17,17,17,17,
	17,17,17,17,17		// Tracks 36..40
};

// Accumulated number of sectors
const int accum_num_sectors[41] = {
	0,
	0,21,42,63,84,105,126,147,168,189,210,231,252,273,294,315,336,
	357,376,395,414,433,452,471,
	490,508,526,544,562,580,
	598,615,632,649,666,
	683,700,717,734,751	// Tracks 36..40
};

// Prototypes
static bool match(const uint8 *p, int p_len, const uint8 *n);
static FILE *open_image_file(const char *path, bool write_mode);
static bool parse_image_file(FILE *f, image_file_desc &desc);


/*
 *  Constructor: Prepare emulation, open image file
 */

ImageDrive::ImageDrive(IEC *iec, const char *filepath) : Drive(iec), the_file(NULL), bam(ram + 0x700), bam_dirty(false)
{
	for (int i=0; i<18; i++) {
		ch[i].mode = CHMOD_FREE;
		ch[i].buf = NULL;
	}
	ch[15].mode = CHMOD_COMMAND;

	Reset();

	// Open image file
	if (change_image(filepath))
		Ready = true;
}


/*
 *  Destructor
 */

ImageDrive::~ImageDrive()
{
	close_image();
}


/*
 *  Close the image file
 */

void ImageDrive::close_image(void)
{
	if (the_file) {
		close_all_channels();
		if (bam_dirty) {
			write_sector(DIR_TRACK, 0, bam);
			bam_dirty = false;
		}
		fclose(the_file);
		the_file = NULL;
	}
}


/*
 *  Open the image file
 */

bool ImageDrive::change_image(const char *path)
{
	// Close old image file
	close_image();

	// Open new image file (try write access first, then read-only)
	write_protected = false;
	the_file = open_image_file(path, true);
	if (the_file == NULL) {
		write_protected = true;
		the_file = open_image_file(path, false);
	}
	if (the_file) {

		// Determine file type and fill in image_file_desc structure
		if (!parse_image_file(the_file, desc)) {
			fclose(the_file);
			the_file = false;
			return false;
		}

		// Read BAM
		read_sector(DIR_TRACK, 0, bam);
		bam_dirty = false;
		return true;
	} else
		return false;
}


/*
 *  Open channel
 */

uint8 ImageDrive::Open(int channel, const uint8 *name, int name_len)
{
	D(bug("ImageDrive::Open channel %d, file %s\n", channel, name));

	set_error(ERR_OK);

	// Channel 15: execute file name as command
	if (channel == 15) {
		execute_cmd(name, name_len);
		return ST_OK;
	}

	if (ch[channel].mode != CHMOD_FREE) {
		set_error(ERR_NOCHANNEL);
		return ST_OK;
	}

	if (name[0] == '$')
		if (channel)
			return open_file_ts(channel, DIR_TRACK, 0);
		else
			return open_directory(name + 1, name_len - 1);

	if (name[0] == '#')
		return open_direct(channel, name);

	return open_file(channel, name, name_len);
}


/*
 *  Open file
 */

uint8 ImageDrive::open_file(int channel, const uint8 *name, int name_len)
{
	uint8 plain_name[NAMEBUF_LENGTH];
	int plain_name_len;
	int mode = FMODE_READ;
	int type = FTYPE_DEL;
	int rec_len = 0;
	parse_file_name(name, name_len, plain_name, plain_name_len, mode, type, rec_len);
	if (plain_name_len > 16)
		plain_name_len = 16;

	D(bug(" plain name %s, type %d, mode %d\n", plain_name, type, mode));

	// Channel 0 is READ, channel 1 is WRITE
	if (channel == 0 || channel == 1) {
		mode = channel ? FMODE_WRITE : FMODE_READ;
		if (type == FTYPE_DEL)
			type = FTYPE_PRG;
	}

	ch[channel].writing = (mode == FMODE_WRITE || mode == FMODE_APPEND);

	// Wildcards are only allowed on reading
	if (ch[channel].writing && (strchr((const char *)plain_name, '*') || strchr((const char *)plain_name, '?'))) {
		set_error(ERR_SYNTAX33);
		return ST_OK;
	}

	// Check for write-protection if writing
	if (ch[channel].writing && write_protected) {
		set_error(ERR_WRITEPROTECT);
		return ST_OK;
	}

	// Relative files are not supported
	if (type == FTYPE_REL) {
		set_error(ERR_UNIMPLEMENTED);
		return ST_OK;
	}

	// Find file in directory
	int dir_track, dir_sector, entry;
	if (find_first_file(plain_name, plain_name_len, dir_track, dir_sector, entry)) {

		// File exists
		D(bug(" file exists, dir track %d, sector %d, entry %d\n", dir_track, dir_sector, entry));
		ch[channel].dir_track = dir_track;
		ch[channel].dir_sector = dir_sector;
		ch[channel].entry = entry;
		uint8 *de = dir + DIR_ENTRIES + entry * SIZEOF_DE;

		// Get file type from existing file if not specified in file name
		if (type == FTYPE_DEL)
			type = de[DE_TYPE] & 7;

		if ((de[DE_TYPE] & 7) != type) {

			// File type doesn't match
			set_error(ERR_FILETYPE);

		} else if (mode == FMODE_WRITE) {

			if (name[0] == '@') {

				// Open old file for overwriting (save-replace)
				return create_file(channel, plain_name, plain_name_len, type, true);

			} else {

				// File to be written already exists, error
				set_error(ERR_FILEEXISTS);
			}

		} else if (mode == FMODE_APPEND) {

			// Open old file for appending
			open_file_ts(channel, de[DE_TRACK], de[DE_SECTOR]);

			// Seek to end of file
			int track = 0, sector = 0, num_blocks = 0;
			while (ch[channel].buf[0]) {
				if (!read_sector(track = ch[channel].buf[0], sector = ch[channel].buf[1], ch[channel].buf))
					return ST_OK;
				num_blocks++;
			}

			// Change channel mode to writing, adjust buffer pointer
			ch[channel].writing = true;
			ch[channel].buf_len = ch[channel].buf[1] + 1;
			ch[channel].buf_ptr = ch[channel].buf + ch[channel].buf_len;
			ch[channel].track = track;
			ch[channel].sector = sector;
			ch[channel].num_blocks = num_blocks;

		} else if (mode == FMODE_M) {

			// Open old file for reading, even if it is not closed
			return open_file_ts(channel, de[DE_TRACK], de[DE_SECTOR]);

		} else {

			// Open old file for reading, error if file is open
			if (de[DE_TYPE] & 0x80)
				return open_file_ts(channel, de[DE_TRACK], de[DE_SECTOR]);
			else
				set_error(ERR_WRITEFILEOPEN);
		}

	} else {

		// File doesn't exist
		D(bug(" file not found\n"));

		// Set file type to SEQ if not specified in file name
		if (type == FTYPE_DEL)
			type = FTYPE_SEQ;

		if (mode == FMODE_WRITE) {

			// Create new file for writing
			return create_file(channel, plain_name, plain_name_len, type);

		} else
			set_error(ERR_FILENOTFOUND);
	}
	return ST_OK;
}


/*
 *  Open channel for reading from file given track/sector of first block
 */

uint8 ImageDrive::open_file_ts(int channel, int track, int sector)
{
	D(bug("open_file_ts track %d, sector %d\n", track, sector));

	// Allocate buffer and set channel mode
	int buf = alloc_buffer(-1);
	if (buf == -1) {
		set_error(ERR_NOCHANNEL);
		return ST_OK;
	}
	ch[channel].buf_num = buf;
	ch[channel].buf = ram + 0x300 + buf * 0x100;
	ch[channel].mode = CHMOD_FILE;

	// On the next call to Read, the first block will be read
	ch[channel].buf[0] = track;
	ch[channel].buf[1] = sector;
	ch[channel].buf_len = 0;

	return ST_OK;
}


/*
 *  Create file and open channel for writing to file
 */

uint8 ImageDrive::create_file(int channel, const uint8 *name, int name_len, int type, bool overwrite)
{
	D(bug("create_file %s, type %d\n", name, type));

	// Allocate buffer
	int buf = alloc_buffer(-1);
	if (buf == -1) {
		set_error(ERR_NOCHANNEL);
		return ST_OK;
	}
	ch[channel].buf_num = buf;
	ch[channel].buf = ram + 0x300 + buf * 0x100;

	// Allocate new directory entry if not overwriting
	if (!overwrite) {
		if (!alloc_dir_entry(ch[channel].dir_track, ch[channel].dir_sector, ch[channel].entry)) {
			free_buffer(buf);
			return ST_OK;
		}
	}
	uint8 *de = dir + DIR_ENTRIES + ch[channel].entry * SIZEOF_DE;

	// Allocate first data block
	ch[channel].track = DIR_TRACK - 1;
	ch[channel].sector = -DATA_INTERLEAVE;
	if (!alloc_next_block(ch[channel].track, ch[channel].sector, DATA_INTERLEAVE)) {
		free_buffer(buf);
		return ST_OK;
	}
	ch[channel].num_blocks = 1;
	D(bug(" first data block on track %d, sector %d\n", ch[channel].track, ch[channel].sector));

	// Write directory entry
	memset(de, 0, SIZEOF_DE);
	de[DE_TYPE] = type;		// bit 7 not set -> open file
	if (overwrite) {
		de[DE_OVR_TRACK] = ch[channel].track;
		de[DE_OVR_SECTOR] = ch[channel].sector;
	} else {
		de[DE_TRACK] = ch[channel].track;
		de[DE_SECTOR] = ch[channel].sector;
	}
	memset(de + DE_NAME, 0xa0, 16);
	memcpy(de + DE_NAME, name, name_len);
	write_sector(ch[channel].dir_track, ch[channel].dir_sector, dir);

	// Set channel descriptor
	ch[channel].mode = CHMOD_FILE;
	ch[channel].writing = true;
	ch[channel].buf_ptr = ch[channel].buf + 2;
	ch[channel].buf_len = 2;
	return ST_OK;
}


/*
 *  Prepare directory as BASIC program (channel 0)
 */

const char type_char_1[] = "DSPUREER";
const char type_char_2[] = "EERSELQG";
const char type_char_3[] = "LQGRL???";

uint8 ImageDrive::open_directory(const uint8 *pattern, int pattern_len)
{
	// Special treatment for "$0"
	if (pattern[0] == '0' && pattern_len == 1) {
		pattern++;
		pattern_len--;
	}

	// Skip everything before the ':' in the pattern
	uint8 *t = (uint8 *)memchr(pattern, ':', pattern_len);
	if (t) {
		t++;
		pattern_len -= t - pattern;
		pattern = t;
	}

	ch[0].mode = CHMOD_DIRECTORY;
	uint8 *p = ch[0].buf_ptr = ch[0].buf = new uint8[8192];

	// Create directory title with disk name, ID and format type
	*p++ = 0x01;	// Load address $0401 (from PET days :-)
	*p++ = 0x04;
	*p++ = 0x01;	// Dummy line link
	*p++ = 0x01;
	*p++ = 0;		// Drive number (0) as line number
	*p++ = 0;
	*p++ = 0x12;	// RVS ON
	*p++ = '\"';

	uint8 *q = bam + BAM_DISK_NAME;
	for (int i=0; i<23; i++) {
		int c;
		if ((c = *q++) == 0xa0)
			*p++ = ' ';		// Replace 0xa0 by space
		else
			*p++ = c;
	}
	*(p-7) = '\"';
	*p++ = 0;

	// Scan all directory blocks
	dir[DIR_NEXT_TRACK] = DIR_TRACK;
	dir[DIR_NEXT_SECTOR] = 1;

	int num_dir_blocks = 0;
	while (dir[DIR_NEXT_TRACK] && num_dir_blocks < num_sectors[DIR_TRACK]) {
		if (!read_sector(dir[DIR_NEXT_TRACK], dir[DIR_NEXT_SECTOR], dir))
			return ST_OK;
		num_dir_blocks++;

		// Scan all 8 entries of a block
		uint8 *de = dir + DIR_ENTRIES;
		for (int j=0; j<8; j++, de+=SIZEOF_DE) {
			if (de[DE_TYPE] && (pattern_len == 0 || match(pattern, pattern_len, de + DE_NAME))) {

				// Dummy line link
				*p++ = 0x01;
				*p++ = 0x01;

				// Line number = number of blocks
				*p++ = de[DE_NUM_BLOCKS_L];
				*p++ = de[DE_NUM_BLOCKS_H];

				// Appropriate number of spaces to align file names
				*p++ = ' ';
				int n = (de[DE_NUM_BLOCKS_H] << 8) + de[DE_NUM_BLOCKS_L];
				if (n<10) *p++ = ' ';
				if (n<100) *p++ = ' ';

				// File name enclosed in quotes
				*p++ = '\"';
				q = de + DE_NAME;
				uint8 c;
				bool m = false;
				for (int i=0; i<16; i++) {
					if ((c = *q++) == 0xa0) {
						if (m)
							*p++ = ' ';			// Replace all 0xa0 by spaces
						else
							m = (*p++ = '\"');	// But the first by a '"'
					} else
						*p++ = c;
				}
				if (m)
					*p++ = ' ';
				else
					*p++ = '\"';			// No 0xa0, then append a space

				// Open files are marked by '*'
				if (de[DE_TYPE] & 0x80)
					*p++ = ' ';
				else
					*p++ = '*';

				// File type
				*p++ = type_char_1[de[DE_TYPE] & 7];
				*p++ = type_char_2[de[DE_TYPE] & 7];
				*p++ = type_char_3[de[DE_TYPE] & 7];

				// Protected files are marked by '<'
				if (de[DE_TYPE] & 0x40)
					*p++ = '<';
				else
					*p++ = ' ';

				// Appropriate number of spaces at the end
				*p++ = ' ';
				if (n >= 10) *p++ = ' ';
				if (n >= 100) *p++ = ' ';
				*p++ = 0;
			}
		}
	}

	// Final line, count number of free blocks
	int n = 0;
	for (int i=1; i<=35; i++) {
		if (i != DIR_TRACK)	// exclude track 18
			n += num_free_blocks(i);
	}

	*p++ = 0x01;		// Dummy line link
	*p++ = 0x01;
	*p++ = n & 0xff;	// Number of free blocks as line number
	*p++ = (n >> 8) & 0xff;

	*p++ = 'B';
	*p++ = 'L';
	*p++ = 'O';
	*p++ = 'C';
	*p++ = 'K';
	*p++ = 'S';
	*p++ = ' ';
	*p++ = 'F';
	*p++ = 'R';
	*p++ = 'E';
	*p++ = 'E';
	*p++ = '.';

	memset(p, ' ', 13);
	p += 13;

	*p++ = 0;
	*p++ = 0;
	*p++ = 0;

	ch[0].buf_len = p - ch[0].buf;
	return ST_OK;
}


/*
 *  Open channel for direct buffer access
 */

uint8 ImageDrive::open_direct(int channel, const uint8 *name)
{
	int buf = -1;

	if (name[1] == 0)
		buf = alloc_buffer(-1);
	else
		if ((name[1] >= '0') && (name[1] <= '3') && (name[2] == 0))
			buf = alloc_buffer(name[1] - '0');

	if (buf == -1) {
		set_error(ERR_NOCHANNEL);
		return ST_OK;
	}

	// The buffers are in the 1541 RAM at $300 and are 256 bytes each
	ch[channel].mode = CHMOD_DIRECT;
	ch[channel].buf = ram + 0x300 + buf * 0x100;
	ch[channel].buf_num = buf;

	// Store actual buffer number in buffer
	ch[channel].buf[1] = buf + '0';
	ch[channel].buf_len = 1;
	ch[channel].buf_ptr = ch[channel].buf + 1;

	return ST_OK;
}


/*
 *  Close channel
 */

uint8 ImageDrive::Close(int channel)
{
	D(bug("ImageDrive::Close channel %d\n", channel));

	switch (ch[channel].mode) {
		case CHMOD_FREE:
			break;
 
		case CHMOD_COMMAND:
			close_all_channels();
			break;

		case CHMOD_DIRECT:
			free_buffer(ch[channel].buf_num);
			ch[channel].buf = NULL;
			ch[channel].mode = CHMOD_FREE;
			break;

		case CHMOD_FILE:
			if (ch[channel].writing) {

				// Current block empty? Then write CR character
				if (ch[channel].buf_len == 2) {
					ch[channel].buf[2] = 0x0d;
					ch[channel].buf_len++;
				}

				// Write last data block
				ch[channel].buf[0] = 0;
				ch[channel].buf[1] = ch[channel].buf_len - 1;
				D(bug(" writing last data block\n"));
				if (!write_sector(ch[channel].track, ch[channel].sector, ch[channel].buf))
					goto free;

				// Close write file in directory
				read_sector(ch[channel].dir_track, ch[channel].dir_sector, dir);
				uint8 *de = dir + DIR_ENTRIES + ch[channel].entry * SIZEOF_DE;
				de[DE_TYPE] |= 0x80;
				de[DE_NUM_BLOCKS_L] = ch[channel].num_blocks & 0xff;
				de[DE_NUM_BLOCKS_H] = ch[channel].num_blocks >> 8;
				if (de[DE_OVR_TRACK]) {
					// Overwriting, free old data blocks and set pointer to new ones
					free_block_chain(de[DE_TRACK], de[DE_SECTOR]);
					de[DE_TRACK] = de[DE_OVR_TRACK];
					de[DE_SECTOR] = de[DE_OVR_SECTOR];
					de[DE_OVR_TRACK] = de[DE_OVR_SECTOR] = 0;
				}
				write_sector(ch[channel].dir_track, ch[channel].dir_sector, dir);
				D(bug(" directory entry updated\n"));
			}
free:		free_buffer(ch[channel].buf_num);
			ch[channel].buf = NULL;
			ch[channel].mode = CHMOD_FREE;
			break;

		case CHMOD_DIRECTORY:
			delete[] ch[channel].buf;
			ch[channel].buf = NULL;
			ch[channel].mode = CHMOD_FREE;
			break;
	}

	return ST_OK;
}


/*
 *  Close all channels
 */

void ImageDrive::close_all_channels()
{
	for (int i=0; i<15; i++)
		Close(i);
	Close(16);
	Close(17);

	cmd_len = 0;
}


/*
 *  Read from channel
 */

uint8 ImageDrive::Read(int channel, uint8 &byte)
{
//	D(bug("ImageDrive::Read channel %d\n", channel));

	switch (ch[channel].mode) {
		case CHMOD_FREE:
			if (current_error == ERR_OK)
				set_error(ERR_FILENOTOPEN);
			break;

		case CHMOD_COMMAND:
			// Read error channel
			byte = *error_ptr++;
			if (--error_len)
				return ST_OK;
			else {
				set_error(ERR_OK);
				return ST_EOF;
			}
			break;

		case CHMOD_FILE:
			if (ch[channel].writing)
				return ST_READ_TIMEOUT;
			if (current_error != ERR_OK)
				return ST_READ_TIMEOUT;

			// Read next block if necessary
			if (ch[channel].buf_len == 0 && ch[channel].buf[0]) {
				D(bug(" reading next data block track %d, sector %d\n", ch[channel].buf[0], ch[channel].buf[1]));
				if (!read_sector(ch[channel].buf[0], ch[channel].buf[1], ch[channel].buf))
					return ST_READ_TIMEOUT;
				ch[channel].buf_ptr = ch[channel].buf + 2;

				// Determine block length
				ch[channel].buf_len = ch[channel].buf[0] ? 254 : ch[channel].buf[1] - 1;
			}

			if (ch[channel].buf_len > 0) {
				byte = *(ch[channel].buf_ptr)++;
				if (--(ch[channel].buf_len) == 0 && ch[channel].buf[0] == 0)
					return ST_EOF;
				else
					return ST_OK;
			} else
				return ST_READ_TIMEOUT;
			break;

		case CHMOD_DIRECTORY:
		case CHMOD_DIRECT:
			if (ch[channel].buf_len > 0) {
				byte = *(ch[channel].buf_ptr)++;
				if (--(ch[channel].buf_len))
					return ST_OK;
				else
					return ST_EOF;
			} else
				return ST_READ_TIMEOUT;
			break;
	}
	return ST_READ_TIMEOUT;
}


/*
 *  Write byte to channel
 */

uint8 ImageDrive::Write(int channel, uint8 byte, bool eoi)
{
//	D(bug("ImageDrive::Write channel %d, byte %02x, eoi %d\n", channel, byte, eoi));

	switch (ch[channel].mode) {
		case CHMOD_FREE:
			if (current_error == ERR_OK)
				set_error(ERR_FILENOTOPEN);
			break;

		case CHMOD_COMMAND:
			// Collect characters and execute command on EOI
			if (cmd_len > 58) {
				set_error(ERR_SYNTAX32);
				return ST_TIMEOUT;
			}

			cmd_buf[cmd_len++] = byte;

			if (eoi) {
				execute_cmd(cmd_buf, cmd_len);
				cmd_len = 0;
			}
			return ST_OK;

		case CHMOD_DIRECTORY:
			set_error(ERR_WRITEFILEOPEN);
			break;

		case CHMOD_FILE:
			if (!ch[channel].writing)
				return ST_TIMEOUT;
			if (current_error != ERR_OK)
				return ST_TIMEOUT;

			// Buffer full?
			if (ch[channel].buf_len >= 256) {

				// Yes, allocate new block
				int track = ch[channel].track, sector = ch[channel].sector;
				if (!alloc_next_block(track, sector, DATA_INTERLEAVE))
					return ST_TIMEOUT;
				ch[channel].num_blocks++;
				D(bug("next data block on track %d, sector %d\n", track, sector));

				// Write buffer with link to new block
				ch[channel].buf[0] = track;
				ch[channel].buf[1] = sector;
				write_sector(ch[channel].track, ch[channel].sector, ch[channel].buf);

				// Reset buffer
				ch[channel].buf_ptr = ch[channel].buf + 2;
				ch[channel].buf_len = 2;
				ch[channel].track = track;
				ch[channel].sector = sector;
			}
			*(ch[channel].buf_ptr)++ = byte;
			ch[channel].buf_len++;
			return ST_OK;

		case CHMOD_DIRECT:
			if (ch[channel].buf_len < 256) {
				*(ch[channel].buf_ptr)++ = byte;
				ch[channel].buf_len++;
				return ST_OK;
			} else
				return ST_TIMEOUT;
			break;
	}
	return ST_TIMEOUT;
}


/*
 *  Reset drive
 */

void ImageDrive::Reset(void)
{
	close_all_channels();

	cmd_len = 0;
	for (int i=0; i<4; i++)
		buf_free[i] = true;

	if (bam_dirty) {
		write_sector(DIR_TRACK, 0, bam);
		bam_dirty = false;
	}

	memset(ram, 0, sizeof(ram));

	read_sector(DIR_TRACK, 0, bam);

	set_error(ERR_STARTUP);
}


/*
 *  Allocate floppy buffer
 *   -> Desired buffer number or -1
 *   <- Allocated buffer number or -1
 */

int ImageDrive::alloc_buffer(int want)
{
	if (want == -1) {
		for (want=3; want>=0; want--)
			if (buf_free[want]) {
				buf_free[want] = false;
				return want;
			}
		return -1;
	}

	if (want < 4)
		if (buf_free[want]) {
			buf_free[want] = false;
			return want;
		} else
			return -1;
	else
		return -1;
}


/*
 *  Free floppy buffer
 */

void ImageDrive::free_buffer(int buf)
{
	buf_free[buf] = true;
}


/*
 *  Search file in directory, return directory track/sector and entry number
 *  false: not found, true: found
 */

// Return true if name 'n' matches pattern 'p'
static bool match(const uint8 *p, int p_len, const uint8 *n)
{
	if (p_len > 16)
		p_len = 16;

	int c = 0;
	while (p_len-- > 0) {
		if (*p == '*')	// Wildcard '*' matches all following characters
			return true;
		if ((*p != *n) && (*p != '?'))	// Wildcard '?' matches single character
			return false;
		p++; n++; c++;
	}

	return *n == 0xa0 || c == 16;
}

bool ImageDrive::find_file(const uint8 *pattern, int pattern_len, int &dir_track, int &dir_sector, int &entry, bool cont)
{
	// Counter to prevent cyclic directories from resulting in an infinite loop
	int num_dir_blocks = 0;

	// Pointer to current directory entry
	uint8 *de = NULL;
	if (cont)
		de = dir + DIR_ENTRIES + entry * SIZEOF_DE;
	else {
		dir[DIR_NEXT_TRACK] = DIR_TRACK;
		dir[DIR_NEXT_SECTOR] = 1;
		entry = 8;
	}

	while (num_dir_blocks < num_sectors[DIR_TRACK]) {

		// Goto next entry
		entry++; de += SIZEOF_DE;
		if (entry >= 8) {

			// Read next directory block
			if (dir[DIR_NEXT_TRACK] == 0)
				return false;
			if (!read_sector(dir_track = dir[DIR_NEXT_TRACK], dir_sector = dir[DIR_NEXT_SECTOR], dir))
				return false;
			num_dir_blocks++;
			entry = 0;
			de = dir + DIR_ENTRIES;
		}

		// Does entry match pattern?
		if (de[DE_TYPE] && match(pattern, pattern_len, de + DE_NAME))
			return true;
	}
	return false;
}

bool ImageDrive::find_first_file(const uint8 *pattern, int pattern_len, int &dir_track, int &dir_sector, int &entry)
{
	return find_file(pattern, pattern_len, dir_track, dir_sector, entry, false);
}

bool ImageDrive::find_next_file(const uint8 *pattern, int pattern_len, int &dir_track, int &dir_sector, int &entry)
{
	return find_file(pattern, pattern_len, dir_track, dir_sector, entry, true);
}


/*
 *  Allocate new entry in directory, returns false on error (usually when
 *  all sectors of track 18 are allocated)
 *  The track/sector and entry numbers are returned
 */

bool ImageDrive::alloc_dir_entry(int &track, int &sector, int &entry)
{
	// First look for free entry in existing directory blocks
	dir[DIR_NEXT_TRACK] = DIR_TRACK;
	dir[DIR_NEXT_SECTOR] = 1;
	while (dir[DIR_NEXT_TRACK]) {
		if (!read_sector(track = dir[DIR_NEXT_TRACK], sector = dir[DIR_NEXT_SECTOR], dir))
			return false;

		uint8 *de = dir + DIR_ENTRIES;
		for (entry=0; entry<8; entry++, de+=SIZEOF_DE) {
			if (de[DE_TYPE] == 0) {
				D(bug(" allocated entry %d in dir track %d, sector %d\n", entry, track, sector));
				return true;
			}
		}
	}

	// No free entry found, allocate new directory block
	int last_track = track, last_sector = sector;
	if (!alloc_next_block(track, sector, DIR_INTERLEAVE))
		return false;
	D(bug(" new directory block track %d, sector %d\n", track, sector));

	// Write link to new block to last block
	dir[DIR_NEXT_TRACK] = track;
	dir[DIR_NEXT_SECTOR] = sector;
	write_sector(last_track, last_sector, dir);

	// Write new empty directory block and return first entry
	memset(dir, 0, 256);
	dir[DIR_NEXT_SECTOR] = 0xff;
	write_sector(track, sector, dir);
	entry = 0;
	return true;
}

/*
 *  Test if block is free in BAM (track/sector are not checked for validity)
 */

bool ImageDrive::is_block_free(int track, int sector)
{
	uint8 *p = bam + BAM_BITMAP + (track - 1) * 4;
	int byte = sector / 8 + 1;
	int bit = sector & 7;
	return p[byte] & (1 << bit);
}


/*
 *  Get number of free blocks on a track
 */

int ImageDrive::num_free_blocks(int track)
{
	return bam[BAM_BITMAP + (track - 1) * 4];
}


/*
 *  Clear BAM, mark all blocks as free
 */

static void clear_bam(uint8 *bam)
{
	for (int track=1; track<=35; track++) {
		static const uint8 num2bits[8] = {0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff};
		(bam + BAM_BITMAP)[(track-1) * 4 + 0] = num_sectors[track];
		(bam + BAM_BITMAP)[(track-1) * 4 + 1] = 0xff;
		(bam + BAM_BITMAP)[(track-1) * 4 + 2] = 0xff;
		(bam + BAM_BITMAP)[(track-1) * 4 + 3] = num2bits[num_sectors[track] - 16];
	}
}


/*
 *  Allocate block in BAM, returns error code
 */

int ImageDrive::alloc_block(int track, int sector)
{
	if (track < 1 || track > 35 || sector < 0 || sector >= num_sectors[track])
		return ERR_ILLEGALTS;

	uint8 *p = bam + BAM_BITMAP + (track - 1) * 4;
	int byte = sector / 8 + 1;
	int bit = sector & 7;

	// Block free?
	if (p[byte] & (1 << bit)) {

		// Yes, allocate and decrement free block count
		D(bug("allocating block at track %d, sector %d\n", track, sector));
		p[byte] &= ~(1 << bit);
		p[0]--;
		bam_dirty = true;
		return ERR_OK;

	} else
		return ERR_NOBLOCK;
}


/*
 *  Free block in BAM, returns error code
 */

int ImageDrive::free_block(int track, int sector)
{
	if (track < 1 || track > 35 || sector < 0 || sector >= num_sectors[track])
		return ERR_ILLEGALTS;

	uint8 *p = bam + BAM_BITMAP + (track - 1) * 4;
	int byte = sector / 8 + 1;
	int bit = sector & 7;

	// Block allocated?
	if (!(p[byte] & (1 << bit))) {

		// Yes, free and increment free block count
		D(bug("freeing block at track %d, sector %d\n", track, sector));
		p[byte] |= (1 << bit);
		p[0]++;
		bam_dirty = true;
	}
	return ERR_OK;
}


/*
 *  Allocate chain of data blocks in BAM
 */

bool ImageDrive::alloc_block_chain(int track, int sector)
{
	uint8 buf[256];
	while (alloc_block(track, sector) == ERR_OK) {
		if (!read_sector(track, sector, buf))
			return false;
		track = buf[0];
		sector = buf[1];
	}
	return true;
}


/*
 *  Free chain of data blocks in BAM
 */

bool ImageDrive::free_block_chain(int track, int sector)
{
	uint8 buf[256];
	while (free_block(track, sector) == ERR_OK) {
		if (!read_sector(track, sector, buf))
			return false;
		track = buf[0];
		sector = buf[1];
	}
	return true;
}


/*
 *  Search and allocate next free block, returns false if no more blocks
 *  are free (ERR_DISKFULL is also set in this case)
 *  "track" and "sector" must be set to the block where the search should
 *  begin
 */

bool ImageDrive::alloc_next_block(int &track, int &sector, int interleave)
{
	// Find track with free blocks
	bool side_changed = false;
	while (num_free_blocks(track) == 0) {
		if (track == DIR_TRACK) {	// Directory doesn't grow to other tracks
full:		track = sector = 0;
			set_error(ERR_DISKFULL);
			return false;
		} else if (track > DIR_TRACK) {
			track++;
			if (track > 35) {
				if (!side_changed)
					side_changed = true;
				else
					goto full;
				track = DIR_TRACK - 1;
				sector = 0;
			}
		} else {
			track--;
			if (track < 1) {
				if (!side_changed)
					side_changed = true;
				else
					goto full;
				track = DIR_TRACK + 1;
				sector = 0;
			}
		}
	}

	// Find next free block on track
	int num = num_sectors[track];
	sector = sector + interleave;
	if (sector >= num) {
		sector -= num;
		if (sector)
			sector--;
	}
	while (!is_block_free(track, sector)) {
		sector++;
		if (sector >= num_sectors[track]) {
			sector = 0;
			while (!is_block_free(track, sector)) {
				sector++;
				if (sector >= num_sectors[track]) {
					// Something is wrong: the BAM free block count for this
					// track was >0, but we found no free blocks
					track = sector = 0;
					set_error(ERR_DIRERROR);
					return false;
				}
			}
		}
	}

	alloc_block(track, sector);
	return true;
}


/*
 *  Sector reading/writing routines
 */

static long offset_from_ts(const image_file_desc &desc, int track, int sector)
{
	if ((track < 1) || (track > desc.num_tracks)
	 || (sector < 0) || (sector >= num_sectors[track]))
		return -1;

	return ((accum_num_sectors[track] + sector) << 8) + desc.header_size;
}

// Get number of sectors per given track
int sectors_per_track(const image_file_desc &desc, int track)
{
	return num_sectors[track];
}

// Get reference to error info byte of given track/sector
uint8 &error_info_for_sector(image_file_desc &desc, int track, int sector)
{
	return desc.error_info[accum_num_sectors[track] + sector];
}

static inline const uint8 &error_info_for_sector(const image_file_desc &desc, int track, int sector)
{
	return desc.error_info[accum_num_sectors[track] + sector];
}

const int conv_job_error[16] = {
	ERR_OK,				// 0 -> 00 OK
	ERR_OK,				// 1 -> 00 OK
	ERR_READ20,			// 2 -> 20 READ ERROR
	ERR_READ21,			// 3 -> 21 READ ERROR
	ERR_READ22,			// 4 -> 22 READ ERROR
	ERR_READ23,			// 5 -> 23 READ ERROR
	ERR_READ24,			// 6 -> 24 READ ERROR (undetected by 1541)
	ERR_WRITE25,		// 7 -> 25 WRITE ERROR
	ERR_WRITEPROTECT,	// 8 -> 26 WRITE PROTECT ON
	ERR_READ27,			// 9 -> 27 READ ERROR
	ERR_WRITE28,		// 10 -> 28 WRITE ERROR
	ERR_DISKID,			// 11 -> 29 DISK ID MISMATCH
	ERR_OK,				// 12 -> 00 OK
	ERR_OK,				// 13 -> 00 OK
	ERR_OK,				// 14 -> 00 OK
	ERR_NOTREADY		// 15 -> 74 DRIVE NOT READY
};

// Read sector, return error code
static int read_sector(FILE *f, const image_file_desc &desc, int track, int sector, uint8 *buffer)
{
	// Convert track/sector to byte offset in file
	long offset = offset_from_ts(desc, track, sector);
	if (offset < 0)
		return ERR_ILLEGALTS;

	if (f == NULL)
		return ERR_NOTREADY;

	fseek(f, offset, SEEK_SET);
	if (fread(buffer, 1, 256, f) != 256)
		return ERR_READ22;
	else {
		unsigned int error = error_info_for_sector(desc, track, sector);
		return conv_job_error[error & 0x0f];
	}
}

// Write sector, return error code
static int write_sector(FILE *f, const image_file_desc &desc, int track, int sector, uint8 *buffer)
{
	// Convert track/sector to byte offset in file
	long offset = offset_from_ts(desc, track, sector);
	if (offset < 0)
		return ERR_ILLEGALTS;

	if (f == NULL)
		return ERR_NOTREADY;

	fseek(f, offset, SEEK_SET);
	if (fwrite(buffer, 1, 256, f) != 256)
		return ERR_WRITE25;
	else
		return ERR_OK;
}

// Read sector and set error message, returns false on error
bool ImageDrive::read_sector(int track, int sector, uint8 *buffer)
{
	int error = ::read_sector(the_file, desc, track, sector, buffer);
	if (error)
		set_error(error, track, sector);
	return error == ERR_OK;
}

// Write sector and set error message, returns false on error
bool ImageDrive::write_sector(int track, int sector, uint8 *buffer)
{
	int error = ::write_sector(the_file, desc, track, sector, buffer);
	if (error)
		set_error(error, track, sector);
	return error == ERR_OK;
}

// Write error info back to image file
static void write_back_error_info(FILE *f, const image_file_desc &desc)
{
	if (desc.type == TYPE_D64 && desc.has_error_info) {
		int num_sectors = desc.num_tracks == 40 ? NUM_SECTORS_40 : NUM_SECTORS_35;
		fseek(f, num_sectors * 256, SEEK_SET);
		fwrite(desc.error_info, num_sectors, 1, f);
	}
}

// Format disk image
static bool format_image(FILE *f, image_file_desc &desc, bool lowlevel, uint8 id1, uint8 id2, const uint8 *disk_name, int disk_name_len)
{
	uint8 p[256];

	if (lowlevel) {

		// Fill buffer with 1541 empty sector pattern (4b 01 01 ...,
		// except on track 1 where it's 01 01 01 ...)
		memset(p, 1, 256);

		// Overwrite all blocks
		for (int track=1; track<=35; track++) {
			if (track == 2)
				p[0] = 0x4b;
			for (int sector=0; sector<num_sectors[track]; sector++) {
				if (write_sector(f, desc, track, sector, p) != ERR_OK)
					return false;
			}
		}

		// Clear and write error info
		memset(desc.error_info, 1, sizeof(desc.error_info));
		write_back_error_info(f, desc);

		// Clear BAM
		memset(p, 0, 256);

	} else {

		// Read BAM
		if (read_sector(f, desc, DIR_TRACK, 0, p) != ERR_OK)
			return false;
	}

	// Create and write empty BAM
	p[BAM_DIR_TRACK] = DIR_TRACK;
	p[BAM_DIR_SECTOR] = 1;
	p[BAM_FMT_TYPE] = 'A';
	clear_bam(p);
	p[BAM_BITMAP + (DIR_TRACK - 1) * 4 + 0] -= 2;	// Allocate BAM and first directory block
	p[BAM_BITMAP + (DIR_TRACK - 1) * 4 + 1] &= 0xfc;
	memset(p + BAM_DISK_NAME, 0xa0, 27);
	if (disk_name_len > 16)
		disk_name_len = 16;
	memcpy(p + BAM_DISK_NAME, disk_name, disk_name_len);
	p[BAM_DISK_ID] = id1;
	p[BAM_DISK_ID + 1] = id2;
	p[BAM_FMT_CHAR] = '2';
	p[BAM_FMT_CHAR + 1] = 'A';
	if (write_sector(f, desc, DIR_TRACK, 0, p) != ERR_OK)
		return false;

	// Create and write empty directory
	memset(p, 0, 256);
	p[1] = 255;
	return write_sector(f, desc, DIR_TRACK, 1, p) == ERR_OK;
}


/*
 *  Execute drive commands
 */

// BLOCK-READ:channel,0,track,sector
void ImageDrive::block_read_cmd(int channel, int track, int sector, bool user_cmd)
{
	if (channel >= 16 || ch[channel].mode != CHMOD_DIRECT) {
		set_error(ERR_NOCHANNEL);
		return;
	}
	if (!read_sector(track, sector, ch[channel].buf))
		return;
	if (user_cmd) {
		ch[channel].buf_len = 256;
		ch[channel].buf_ptr = ch[channel].buf;
	} else {
		ch[channel].buf_len = ch[channel].buf[0];
		ch[channel].buf_ptr = ch[channel].buf + 1;
	}
}

// BLOCK-WRITE:channel,0,track,sector
void ImageDrive::block_write_cmd(int channel, int track, int sector, bool user_cmd)
{
	if (write_protected) {
		set_error(ERR_WRITEPROTECT);
		return;
	}
	if (channel >= 16 || ch[channel].mode != CHMOD_DIRECT) {
		set_error(ERR_NOCHANNEL);
		return;
	}
	if (!user_cmd)
		ch[channel].buf[0] = ch[channel].buf_len ? ch[channel].buf_len - 1 : 1;
	if (!write_sector(track, sector, ch[channel].buf))
		return;
	if (!user_cmd) {
		ch[channel].buf_len = 1;
		ch[channel].buf_ptr = ch[channel].buf + 1;
	}
}

// BLOCK-ALLOCATE:0,track,sector
void ImageDrive::block_allocate_cmd(int track, int sector)
{
	int err = alloc_block(track, sector);
	if (err) {
		if (err == ERR_NOBLOCK) {
			// Find next free block and return its track/sector address in the
			// error message (only look on higher tracks)
			for (;;) {
				sector++;
				if (sector >= num_sectors[track]) {
					track++;
					sector = 0;
					if (track > 35) {
						set_error(ERR_NOBLOCK, 0, 0);
						return;
					}
				}
				if (is_block_free(track, sector)) {
					set_error(ERR_NOBLOCK, track, sector);
					return;
				}
			}
		} else
			set_error(err, track, sector);
	}
}

// BLOCK-FREE:0,track,sector
void ImageDrive::block_free_cmd(int track, int sector)
{
	int err = free_block(track, sector);
	if (err)
		set_error(err, track, sector);
}

// BUFFER-POINTER:channel,pos
void ImageDrive::buffer_pointer_cmd(int channel, int pos)
{
	if (channel >= 16 || ch[channel].mode != CHMOD_DIRECT) {
		set_error(ERR_NOCHANNEL);
		return;
	}
	ch[channel].buf_ptr = ch[channel].buf + pos;
	ch[channel].buf_len = 256 - pos;
}

// M-R<adr low><adr high>[<number>]
void ImageDrive::mem_read_cmd(uint16 adr, uint8 len)
{
	error_len = len;
	if (adr >= 0x300 && adr < 0x1000) {
		// Read from RAM
		error_ptr = (char *)ram + (adr & 0x7ff);
	} else if (adr >= 0xc000) {
		// Read from ROM
		error_ptr = (char *)(TheC64->ROM1541) + (adr - 0xc000);
	} else {
		unsupp_cmd();
		memset(error_buf, 0, len);
		error_ptr = error_buf;
	}
}

// M-W<adr low><adr high><number><data...>
void ImageDrive::mem_write_cmd(uint16 adr, uint8 len, uint8 *p)
{
	while (len) {
		if (adr >= 0x300 && adr < 0x1000) {
			// Write to RAM
			ram[adr & 0x7ff] = *p;
		} else if (adr < 0xc000) {
			unsupp_cmd();
			return;
		}
		len--; adr++; p++;
	}
}

//   COPY:new=file1,file2,...
//        ^   ^
// new_file   old_files
void ImageDrive::copy_cmd(const uint8 *new_file, int new_file_len, const uint8 *old_files, int old_files_len)
{
	// Check if destination file is already present
	int dir_track, dir_sector, entry;
	if (find_first_file(new_file, new_file_len, dir_track, dir_sector, entry)) {
		set_error(ERR_FILEEXISTS);
		return;
	}

	// Loop for all source files
	bool first = true;
	while (old_files_len > 0) {
		uint8 *comma = (uint8 *)memchr(old_files, ',', old_files_len);
		int name_len = comma ? comma - old_files : old_files_len;

		// Check if source file is present
		if (!find_first_file(old_files, name_len, dir_track, dir_sector, entry)) {
			set_error(ERR_FILENOTFOUND);
			Close(17);
			return;
		}
		uint8 *de = dir + DIR_ENTRIES + entry * SIZEOF_DE;
		uint8 type = de[DE_TYPE] & 7, track = de[DE_TRACK], sector = de[DE_SECTOR];

		// If this is the first source file, open internal write channel for destination file
		if (first) {
			create_file(17, new_file, new_file_len, type, false);
			if (ch[17].mode == CHMOD_FREE)
				return;
			first = false;
		}

		// Open internal read channel for source file
		open_file_ts(16, track, sector);
		if (ch[16].mode == CHMOD_FREE) {
			Close(17);
			return;
		}

		// Copy file
		uint8 byte, st;
		do {
			st = Read(16, byte);
			Write(17, byte, false);
		} while (st == ST_OK);
		Close(16);
		if (st != ST_EOF) {
			Close(17);
			return;
		}

		if (comma) {
			old_files_len -= name_len + 1;
			old_files = comma + 1;
		} else
			old_files_len = 0;
	}
	Close(17);
}

// RENAME:new=old
//        ^   ^
// new_file   old_file
void ImageDrive::rename_cmd(const uint8 *new_file, int new_file_len, const uint8 *old_file, int old_file_len)
{
	// Check if destination file is already present
	int dir_track, dir_sector, entry;
	if (find_first_file(new_file, new_file_len, dir_track, dir_sector, entry)) {
		set_error(ERR_FILEEXISTS);
		return;
	}

	// Check if source file is present
	if (!find_first_file(old_file, old_file_len, dir_track, dir_sector, entry)) {
		set_error(ERR_FILENOTFOUND);
		return;
	}

	// Check for write-protection
	if (write_protected) {
		set_error(ERR_WRITEPROTECT);
		return;
	}

	// Rename file in directory entry
	uint8 *p = dir + DIR_ENTRIES + entry * SIZEOF_DE;
	memset(p + DE_NAME, 0xa0, 16);
	memcpy(p + DE_NAME, new_file, new_file_len);
	write_sector(dir_track, dir_sector, dir);
}

// SCRATCH:file1,file2,...
//         ^
//         files
void ImageDrive::scratch_cmd(const uint8 *files, int files_len)
{
	// Check for write-protection
	if (write_protected) {
		set_error(ERR_WRITEPROTECT);
		return;
	}

	// Loop for all files
	int num_files = 0;
	while (files_len > 0) {
		uint8 *comma = (uint8 *)memchr(files, ',', files_len);
		int name_len = comma ? comma - files : files_len;

		int dir_track, dir_sector, entry;
		if (find_first_file(files, name_len, dir_track, dir_sector, entry)) {
			do {
				uint8 *de = dir + DIR_ENTRIES + entry * SIZEOF_DE;

				// File protected? Then skip
				if (de[DE_TYPE] & 0x40)
					continue;

				// Free allocated data blocks and side sectors
				free_block_chain(de[DE_TRACK], de[DE_SECTOR]);
				free_block_chain(de[DE_SIDE_TRACK], de[DE_SIDE_SECTOR]);

				// Clear file type
				de[DE_TYPE] = 0;

				// Write directory block back
				write_sector(dir_track, dir_sector, dir);
				num_files++;
			} while (find_next_file(files, name_len, dir_track, dir_sector, entry));
		}

		if (comma) {
			files_len -= name_len + 1;
			files = comma + 1;
		} else
			files_len = 0;
	}

	// Report number of files scratched
	set_error(ERR_SCRATCHED, num_files);
}

// INITIALIZE
void ImageDrive::initialize_cmd(void)
{
	// Close all channels and re-read BAM
	close_all_channels();
	if (bam_dirty) {
		write_sector(DIR_TRACK, 0, bam);
		bam_dirty = false;
	}
	read_sector(DIR_TRACK, 0, bam);
}

// NEW:name,id
//     ^   ^
//  name   comma (or NULL)
void ImageDrive::new_cmd(const uint8 *name, int name_len, const uint8 *comma)
{
	// Check for write-protection
	if (write_protected) {
		set_error(ERR_WRITEPROTECT);
		return;
	}

	// Remember current ID
	uint8 id1 = bam[BAM_DISK_ID], id2 = bam[BAM_DISK_ID + 1];

	// Formatting with ID?
	if (comma) {

		close_all_channels();

		// Clear BAM buffer
		memset(bam, 0, 256);

		// Get ID from command
		if (comma[1]) {
			id1 = comma[1];
			id2 = comma[2] ? comma[2] : ' ';
		} else {
			id1 = id2 = ' ';
		}
	}

	// Format disk image
	format_image(the_file, desc, comma, id1, id2, name, name_len);

	// Re-read BAM
	read_sector(DIR_TRACK, 0, bam);
	bam_dirty = false;
}

// VALIDATE
void ImageDrive::validate_cmd(void)
{
	// Backup of old BAM in case something goes amiss
	uint8 old_bam[256];
	memcpy(old_bam, bam, 256);

	// Clear BAM
	clear_bam(bam);
	bam_dirty = true;

	// Allocate BAM and directory
	if (!alloc_block_chain(DIR_TRACK, 0)) {
		memcpy(bam, old_bam, 256);
		return;
	}

	// Allocate all file data and side sector blocks
	int dir_track, dir_sector, entry;
	if (find_first_file((uint8 *)"*", 1, dir_track, dir_sector, entry)) {
		do {
			uint8 *de = dir + DIR_ENTRIES + entry * SIZEOF_DE;

			if (de[DE_TYPE] & 0x80) {
				// Closed file, allocate all file data and side sector blocks
				if (!alloc_block_chain(de[DE_TRACK], de[DE_SECTOR]) || !alloc_block_chain(de[DE_SIDE_TRACK], de[DE_SIDE_SECTOR])) {
					memcpy(bam, old_bam, 256);
					return;
				}
			} else {
				// Open file, delete it
				de[DE_TYPE] = 0;
				write_sector(dir_track, dir_sector, dir);
			}
		} while (find_next_file((uint8 *)"*", 1, dir_track, dir_sector, entry));
	}
}


/*
 *  Check whether file with given header (64 bytes) and size looks like one
 *  of the file types supported by this module
 */

static bool is_d64_file(const uint8 *header, long size)
{
	return size == NUM_SECTORS_35 * 256 || size == NUM_SECTORS_35 * 257
	    || size == NUM_SECTORS_40 * 256 || size == NUM_SECTORS_40 * 257;
}

static bool is_ed64_file(const uint8 *header, long size)
{
	// 35-track d64 file with header ID at the end (only used internally for
	// converted zipcode files)
	return size == NUM_SECTORS_35 * 256 + 2;
}

static bool is_x64_file(const uint8 *header, long size)
{
	return memcmp(header, "C\x15\x41\x64\x01\x02", 6) == 0;
}

static bool is_zipcode_file(const char *path)
{
#if 0
	string base, part;
	SplitPath(path, base, part);
	return part.length() > 2 && part[0] >= '1' && part[0] <= '4' && part[1] == '!';
#else
	return false;
#endif
}

bool IsImageFile(const char *path, const uint8 *header, long size)
{
	return is_d64_file(header, size) || is_x64_file(header, size) || is_zipcode_file(path);
}


#if 0
/*
 *  Convert zipcode file to extended d64 file (d64 file with header ID)
 */

static FILE *open_zipcode_file(FILE *old, int num, const string &base, string &part, uint8 &id1, uint8 &id2)
{
	if (old)
		fclose(old);
	part[0] = num + '1';
	FILE *f = fopen(AddToPath(base, part).c_str(), "rb");
	if (f == NULL)
		return NULL;
	if (fseek(f, 2, SEEK_SET) < 0) {
		fclose(f);
		return NULL;
	}
	if (num == 0) {
		id1 = getc(f);
		id2 = getc(f);
	}
	return f;
}

static FILE *convert_zipcode_to_ed64(const string &path)
{
	FILE *in = NULL, *out = NULL;
	uint8 id1, id2;

	// Split input file name
	string base, part;
	SplitPath(path, base, part);

	// Open output file
	out = tmpfile();
	if (out == NULL)
		goto error;

	// Decode all tracks
	for (int track=1; track<=35; track++) {
		int max_sect = 17 + ((track < 31) ? 1 : 0) + ((track < 25) ? 1 : 0) + ((track < 18) ? 2 : 0);

		// Select appropriate input file
		switch (track) {
			case 1:
				if ((in = open_zipcode_file(NULL, 0, base, part, id1, id2)) == NULL)
					goto error;
				break;
			case 9:
				if ((in = open_zipcode_file(in, 1, base, part, id1, id2)) == NULL)
					goto error;
				break;
			case 17:
				if ((in = open_zipcode_file(in, 2, base, part, id1, id2)) == NULL)
					goto error;
				break;
			case 26:
				if ((in = open_zipcode_file(in, 3, base, part, id1, id2)) == NULL)
					goto error;
				break;
		}

		// Clear "sector read" flags
		bool sect_flag[21];
		for (int i=0; i<max_sect; i++)
			sect_flag[i] = false;

		// Read track
		uint8 act_track[21 * 256];
		for (int i=0; i<max_sect; i++) {

			// Read and verify track/sector number
			uint8 t = getc(in);
			uint8 s = getc(in);
			if ((t & 0x3f) != track || s >= max_sect || sect_flag[s] || feof(in))
				goto error;
			sect_flag[s] = true;
			uint8 *p = act_track + s * 256;

			// Uncompress sector
			if (t & 0x80) {
				// Run-length encoded sector
				uint8 len = getc(in);
				uint8 rep = getc(in);
				int count = 0;
				for (int j=0; j<len; j++) {
					if (feof(in))
						goto error;
					uint8 c = getc(in);
					if (c != rep)
						p[count++] = c;
					else {
						uint8 repnum = getc(in);
						if (feof(in))
							goto error;
						c = getc(in);
						j += 2;
						for (int k=0; k<repnum; k++)
							p[count++] = c;
					}
				}
			} else if (t & 0x40) {
				// Sector filled with constant byte
				if (feof(in))
					goto error;
				uint8 c = getc(in);
				memset(p, c, 256);
			} else {
				// Plain sector
				if (fread(p, 1, 256, in) != 256)
					goto error;
			}
		}

		// Write track
		if (fwrite(act_track, 256, max_sect, out) != (size_t)max_sect)
			goto error;
	}

	// Write header ID
	putc(id1, out);
	putc(id2, out);

	// Done
	fclose(in);
	fseek(out, 0, SEEK_SET);
	return out;

error:
	if (in)
		fclose(in);
	if (out)
		fclose(out);
	return NULL;
}
#endif


/*
 *  Open disk image file, return file handle
 */

static FILE *open_image_file(const char *path, bool write_mode)
{
#if 0
	if (is_zipcode_file(path)) {
		if (write_mode)
			return NULL;
		else
			return convert_zipcode_to_ed64(path);
	} else
#endif
		return fopen(path, write_mode ? "r+b" : "rb");
}


/*
 *  Parse image file and fill in image_file_desc structure
 */

static bool parse_d64_file(FILE *f, image_file_desc &desc, bool has_header_id)
{
	// .d64 files have no header
	desc.type = has_header_id ? TYPE_ED64 : TYPE_D64;
	desc.header_size = 0;

	// Determine number of tracks
	fseek(f, 0, SEEK_END);
	long size = ftell(f);
	if (size == NUM_SECTORS_40 * 256 || size == NUM_SECTORS_40 * 257)
		desc.num_tracks = 40;
	else
		desc.num_tracks = 35;

	if (has_header_id) {
		// Read header ID from image file (last 2 bytes)
		fseek(f, -2, SEEK_END);
		desc.id1 = getc(f);
		desc.id2 = getc(f);
	} else {
		// Read header ID from BAM (use error_info as buffer)
		fseek(f, accum_num_sectors[18] * 256, SEEK_SET);
		fread(desc.error_info, 1, 256, f);
		desc.id1 = desc.error_info[BAM_DISK_ID];
		desc.id2 = desc.error_info[BAM_DISK_ID + 1];
	}

	// Read error info
	memset(desc.error_info, 1, sizeof(desc.error_info));
	if (size == NUM_SECTORS_35 * 257) {
		fseek(f, NUM_SECTORS_35 * 256, SEEK_SET);
		fread(desc.error_info, NUM_SECTORS_35, 1, f);
		desc.has_error_info = true;
	} else if (size == NUM_SECTORS_40 * 257) {
		fseek(f, NUM_SECTORS_40 * 256, SEEK_SET);
		fread(desc.error_info, NUM_SECTORS_40, 1, f);
		desc.has_error_info = true;
	} else
		desc.has_error_info = false;

	return true;
}

static bool parse_x64_file(FILE *f, image_file_desc &desc)
{
	desc.type = TYPE_X64;
	desc.header_size = 64;

	// Read number of tracks
	fseek(f, 7, SEEK_SET);
	desc.num_tracks = getc(f);
	if (desc.num_tracks < 35 || desc.num_tracks > 40)
		return false;

	// Read header ID from BAM (use error_info as buffer)
	fseek(f, desc.header_size + accum_num_sectors[18] * 256, SEEK_SET);
	fread(desc.error_info, 1, 256, f);
	desc.id1 = desc.error_info[BAM_DISK_ID];
	desc.id2 = desc.error_info[BAM_DISK_ID + 1];

	// .x64 files have no error info
	memset(desc.error_info, 1, sizeof(desc.error_info));
	desc.has_error_info = false;
	return true;
}

static bool parse_image_file(FILE *f, image_file_desc &desc)
{
	// Read header
	uint8 header[64];
	fread(header, 1, sizeof(header), f);

	// Determine file size
	fseek(f, 0, SEEK_END);
	long size = ftell(f);

	// Determine file type and fill in image_file_desc structure
	if (is_x64_file(header, size))
		return parse_x64_file(f, desc);
	else if (is_d64_file(header, size))
		return parse_d64_file(f, desc, false);
	else if (is_ed64_file(header, size))
		return parse_d64_file(f, desc, true);
	else
		return false;
}


/*
 *  Read directory of disk image file into (empty) c64_dir_entry vector,
 *  returns false on error
 */

bool ReadImageDirectory(const char *path, vector<c64_dir_entry> &vec)
{
	bool result = false;

	// Open file
	FILE *f = open_image_file(path, false);
	if (f) {
		int num_dir_blocks = 0;

		// Determine file type and fill in image_file_desc structure
		image_file_desc desc;
		if (!parse_image_file(f, desc))
			goto done;

		// Scan all directory blocks
		uint8 dir[256];
		dir[DIR_NEXT_TRACK] = DIR_TRACK;
		dir[DIR_NEXT_SECTOR] = 1;

		while (dir[DIR_NEXT_TRACK] && num_dir_blocks < num_sectors[DIR_TRACK]) {
			if (read_sector(f, desc, dir[DIR_NEXT_TRACK], dir[DIR_NEXT_SECTOR], dir) != ERR_OK)
				break;
			num_dir_blocks++;

			// Scan all 8 entries of a block
			uint8 *de = dir + DIR_ENTRIES;
			for (int j=0; j<8; j++, de+=SIZEOF_DE) {

				// Skip empty entries
				if (de[DE_TYPE] == 0)
					continue;

				// Convert file name (strip everything after and including the first trailing space)
				uint8 name_buf[17];
				memcpy(name_buf, de + DE_NAME, 16);
				name_buf[16] = 0;
				uint8 *p = (uint8 *)memchr(name_buf, 0xa0, 16);
				if (p)
					*p = 0;

				// Convert file type
				int type = de[DE_TYPE] & 7;
				if (type > 4)
					type = FTYPE_UNKNOWN;

				// Read start address
				uint8 sa_lo = 0, sa_hi = 0;
				uint8 buf[256];
				if (read_sector(f, desc, de[DE_TRACK], de[DE_SECTOR], buf) == ERR_OK) {
					sa_lo = buf[2];
					sa_hi = buf[3];
				}

				// Add entry
				vec.push_back(c64_dir_entry(name_buf, type, !(de[DE_TYPE] & 0x80), de[DE_TYPE] & 0x40, ((de[DE_NUM_BLOCKS_H] << 8) + de[DE_NUM_BLOCKS_L]) * 254, 0, sa_lo, sa_hi));
			}
		}

		result = true;
done:	fclose(f);
	}
	return result;
}


/*
 *  Create new blank disk image file, returns false on error
 */

bool CreateImageFile(const char *path)
{
	// Open file for writing
	FILE *f = fopen(path, "wb");
	if (f == NULL)
		return false;

	// Create descriptor
	image_file_desc desc;
	desc.type = TYPE_D64;
	desc.header_size = 0;
	desc.num_tracks = 35;
	desc.id1 = 'F';
	desc.id1 = 'R';
	memset(desc.error_info, 1, sizeof(desc.error_info));
	desc.has_error_info = false;

	// Format image file
	if (!format_image(f, desc, true, 'F', 'R', (uint8 *)"D64 FILE", 8)) {
		fclose(f);
		remove(path);
		return false;
	}

	// Close file
	fclose(f);
	return true;
}