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

    readti -- Creates sector images from floppy disks written on the TI-99/4A
              and Geneve computer family
    
    Copyright (C) 2008 Michael Zapf (Michael.Zapf@mizapf.de)

    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 3 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, see <http://www.gnu.org/licenses/>.

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

#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/fd.h>
#include <linux/fdreg.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <fcntl.h>
#include <sys/stat.h>

#define COMMAND 0
#define PHEAD 1
#define LCYL 2
#define LHEAD 3
#define SECTOR 4
#define SECTSIZE 5
#define SECTPERCYL 6
#define GAP 7
#define SIZE2 8

#define FM 1
#define MFM 0
#define SINGLE 1
#define DOUBLE 2

struct geometry_t 
{
	int tracks;
	int sectors;
	int sides;
	int rate;
	int density;
	int stepping;
} geometry;

int verbose;

struct floppy_raw_cmd raw_cmd;

void recalibrate(int fd)
{
	int tmp, size;
	int head = 0;
	int track = 0;
	
	raw_cmd.cmd[PHEAD] = head*4;  // 0 and 4 are the sides
	raw_cmd.cmd[LHEAD] = head;
	raw_cmd.cmd_count = 2;
	raw_cmd.length = 0x100;
	size = raw_cmd.length;    

	raw_cmd.rate = geometry.rate;
	raw_cmd.flags = FD_RAW_INTR | FD_RAW_NEED_SEEK;

	raw_cmd.cmd[COMMAND] = FD_RECALIBRATE;
	if (geometry.density==FM) raw_cmd.cmd[0] &= ~0x40;

	raw_cmd.cmd[LCYL] = track;
	raw_cmd.track = raw_cmd.cmd[LCYL]*geometry.stepping;

	tmp = ioctl( fd, FDRAWCMD, &raw_cmd );
	if (verbose) printf("Recalibrate...\n"); 
	if ( tmp < 0 ){
		perror("error executing command");
		exit(1);
	}
}

void loadsector(int fd, int fdout, int track, int sector, int head)
{
	int tmp, size;
	
	char buffer[ 512 * 2 * 24 ];

	raw_cmd.data = buffer;
	raw_cmd.cmd[PHEAD] = head*4;  // 0 and 4 are the sides
	raw_cmd.cmd[LHEAD] = head;
	raw_cmd.cmd[SECTOR] = sector;
	raw_cmd.cmd[SECTSIZE] = 1;   // 0 = 128, 1 = 256, 2 = 512, 3 = 1024 ...
	raw_cmd.cmd[SECTPERCYL] = geometry.sectors;
	raw_cmd.cmd[GAP] = 0x1b;     // not needed, default
	raw_cmd.cmd[SIZE2] = 0xff;   // not needed, default
	raw_cmd.cmd_count = 9;
	raw_cmd.length = 0x100;
	size = raw_cmd.length;    

	raw_cmd.rate = geometry.rate;
	raw_cmd.flags = FD_RAW_READ | FD_RAW_INTR | FD_RAW_NEED_SEEK;

	raw_cmd.cmd[COMMAND] = FD_READ;
	if (geometry.density==FM) raw_cmd.cmd[0] &= ~0x40;

	raw_cmd.cmd[LCYL] = track;
	raw_cmd.track = raw_cmd.cmd[LCYL]*geometry.stepping;

	tmp = ioctl( fd, FDRAWCMD, &raw_cmd );
//	printf("Reading track %d, head %d, status %2x\n", track, head, raw_cmd.reply[0]); 
	if ( tmp < 0 ){
		perror("error executing command");
		exit(1);
	}
	if (raw_cmd.reply[0] > 0x07) 
	{
		printf("Read error reading sector %d on track %d, side %d. Filling with 0xdead.\n", sector, track, head+1);
		wmemset(buffer, 0xaddeadde, size/4);
	}
	write(fdout, buffer, size );
}

void loadtrack(int fd, int fdout, int track, int head)
{
	int tmp, size;
	
	char buffer[ 512 * 2 * 24 ];

	raw_cmd.data = buffer;
	raw_cmd.cmd[PHEAD] = head*4;  // 0 and 4 are the sides
	raw_cmd.cmd[LHEAD] = head;
	raw_cmd.cmd[SECTOR] = 0;
	raw_cmd.cmd[SECTSIZE] = 1;   // 0 = 128, 1 = 256, 2 = 512, 3 = 1024 ...
	raw_cmd.cmd[SECTPERCYL] = geometry.sectors;
	raw_cmd.cmd[GAP] = 0x1b;     // not needed, default
	raw_cmd.cmd[SIZE2] = 0xff;   // not needed, default
	raw_cmd.cmd_count = 9;
	raw_cmd.length = 0x100 * geometry.sectors;
	size = raw_cmd.length;    

	raw_cmd.rate = geometry.rate;
	raw_cmd.flags = FD_RAW_READ | FD_RAW_INTR | FD_RAW_NEED_SEEK;

	raw_cmd.cmd[COMMAND] = FD_READ;
	if (geometry.density==FM) raw_cmd.cmd[0] &= ~0x40;

	raw_cmd.cmd[LCYL] = track;
	raw_cmd.track = raw_cmd.cmd[LCYL]*geometry.stepping;

	tmp = ioctl( fd, FDRAWCMD, &raw_cmd );
//	printf("Reading track %d, head %d, status %2x\n", track, head, raw_cmd.reply[0]); 
	if ( tmp < 0 ){
		perror("error executing command");
		exit(1);
	}
	if (raw_cmd.reply[0] > 0x07) 
	{
		int sector;
		if (verbose) printf("Read error reading track %d, side %d. Trying to read separate sectors.\n", track, head+1);
		recalibrate(fd);
		for (sector=0; sector < geometry.sectors; sector++)
		{
			loadsector(fd, fdout, track, sector, head);
		}
	}
	else
		write(fdout, buffer, size );
}

unsigned char *try_readid(int fd, int rate, int head, int track, int single_density)
{
	int tmp, size;
	int need_seek = 1;

	raw_cmd.cmd[COMMAND] = FD_READID;
	raw_cmd.cmd[PHEAD] = head*4;  // 0 and 4 are the sides
	raw_cmd.cmd_count = 2;
	raw_cmd.rate = rate;
	
	raw_cmd.flags = FD_RAW_INTR;
	if (need_seek) raw_cmd.flags |= FD_RAW_NEED_SEEK;
	raw_cmd.track = track;
	
	if (single_density) raw_cmd.cmd[0] &= ~0x40;

	tmp = ioctl( fd, FDRAWCMD, &raw_cmd );
		
	if ( tmp < 0 ){
		perror("error executing command");
		exit(1);
	}
	
	return raw_cmd.reply;
}

/* Note: This analysis cannot detect whether a disk is only 40 tracks when it
   was once formatted as 80 tracks
*/

void analyze_disk(int fd)
{
	// fdrawcmd readid 0 rate=0 need_seek track=0
	char *status;
	// Determine rate  
	int rate, density;
	int sectors, i, heads, stepping, tracks;
	density = MFM;
	
	for (rate=0; rate < 4; rate++) 
	{
		status = try_readid(fd, rate, 0, 0, density);
		if (status[0] < 0x08) break;
	}
	if (rate==4)
	{
		// Try single density
		density = FM;
		for (rate=0; rate < 4; rate++) 
		{
			status = try_readid(fd, rate, 0, 0, density);
			if (status[0] < 0x08) break;
		}
		if (rate==4)
		{
			printf("Error ... could not determine rate. Bad floppy disk?\n");
			exit(1);
		}
	}

	// Determine number of sides
	status = try_readid(fd, rate, 1, 0, density);
	if (status[0] < 0x08) heads = 2;
	else {
		// Try another track
		recalibrate(fd);
		status = try_readid(fd, rate, 1, 18, density);
		if (status[0] < 0x08) heads = 2;
		else 
			heads = 1;
	}

	// Determine number of sectors per track
	sectors = 0;
	for (i=0; i < 50; i++)
	{
		status = try_readid(fd, rate, 0, 0, density);
		if (status[0] > 0x08) 
		{
			printf("Error ... could not read a sector. Bad floppy disk?\n");
			exit(1);
		}
		if (status[5] > sectors) sectors = status[5]; 
	}
	sectors = sectors+1;

	// Determine single or double stepping
	status = try_readid(fd, rate, 0, 2, density);
	if (status[0] > 0x08) 
	{
		printf("Error ... could not read a sector. Bad floppy disk?\n");
		exit(1);
	}
	if (status[3]==2)
	{
		stepping=SINGLE;
	}
	else
	{
		if (status[3]==1)
		{
			stepping = DOUBLE;
		}
		else 
		{
			printf("Error ... could not determine stepping. Bad floppy disk?\n");
			exit(1);
		}
	}	
	
	// Determine number of tracks
	// Heuristic: 80 tracks/40 tracks, or 70 tracks/35 tracks
	// Double stepping means a maximum of 40 or 35 tracks.
	tracks = 80;
	if (stepping==1) {
		status = try_readid(fd, rate, 0, tracks-1, density);
		if (status[0] > 0x08) 
		{
			tracks = 70;
			status = try_readid(fd, rate, 0, tracks-1, density);
			if (status[0] > 0x08)
			{
				tracks = 40;
				status = try_readid(fd, rate, 0, tracks-1, density);
				if (status[0] > 0x08)
				{
					tracks = 35;
					status = try_readid(fd, rate, 0, tracks-1, density);
					if (status[0] > 0x08)
					{
						printf("Cannot determine last track. Bad floppy disk?\n");
						exit(1);
					}
				}
			}
		}
	}
	else 
	{ // double stepping; 40 or 35
		tracks = 40;
		status = try_readid(fd, rate, 0, 2*(tracks-1), density);
		if (status[0] > 0x08)
		{
			tracks = 35;
			status = try_readid(fd, rate, 0, 2*(tracks-1), density);
			if (status[0] > 0x08)
			{
				printf("Cannot determine last track. Bad floppy disk?\n");
				exit(1);
			}
		}
	}
	
	geometry.rate = rate;
	geometry.density = density;
	geometry.sectors = sectors;
	geometry.sides = heads;
	geometry.stepping = stepping;
	geometry.tracks = tracks;
	
	if (verbose)
	{
		printf("Rate = %d\n", rate);	
		printf("Single density = %d\n", density);
		printf("Sectors = %d\n", sectors);
		printf("Heads = %d\n", heads);
		printf("physical/logical tracks = %d\n", stepping);
		printf("Logical tracks = %d\n", tracks);
	}
}

int main(int argc, char **argv)
{
	int fd, fdout, i;
	int index=1;
	verbose = 0;
	
	if (argc < 3)
	{
		printf("Usage: readti [-v] device (=/dev/fd0) outfile\n");
		exit(1);
	}
	if (strcmp(argv[index],"-v")==0)
	{
		verbose = 1;
		index++;
		if (argc < 4)
		{
			printf("Usage: readti [-v] device (=/dev/fd0) outfile\n");
			exit(1);
		}
	}
	
	fd = open(argv[index++], O_ACCMODE | O_NDELAY);
	if ( fd < 0 ){
		perror("error opening floppy");
		exit(1);
	}

	fdout = open(argv[index++], O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
	if ( fdout < 0 ){
		perror("error opening output file");
		exit(1);
	}

	analyze_disk(fd);
	
	for (i=0; i < geometry.tracks; i++)
	{
		loadtrack(fd, fdout, i, 0);
	}		
	if (geometry.sides==2)
	{
		for (i=geometry.tracks-1; i >=0; i--)
		{
			loadtrack(fd, fdout, i, 1);
		}
	}		

	if (close(fd)) perror("close error for input file");
	if (close(fdout)) perror("close error for output file");
	return 0;
}