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// license:BSD-3-Clause
// copyright-holders:Nigel Barnes
/***************************************************************************
BBC Micro 8271 protected disk image format
Disk image format
***************************************************************************/
#include "emu.h"
#include "fsd_dsk.h"
/*********************************************************************
BBC Micro 8271 protected disk image format
Header:
=======
Identifier: "FSD" string literal 3 bytes
Creator: 5 bytes; date of creation/author
Title: Character string (unlimited length; may contain any but null)
Title_End: 0x00 byte literal 1 byte
Num_Tr: xx 1 byte, number of tracks
For each track
==============
track_num: 1 byte
num_sec: 1 byte (00 == unformatted)
readable: 1 byte (00 == unreadable, ff ==readable)
If readable:
For each sector
===============
Track_ID: 1 byte
Head_number: 1 byte
Sector_ID: 1 byte
reported_size: 1 byte (2^{7+x}; 0 ==>128, 1 ==> 256, 2==>512, 3==>1024 etc)
real_size: 1 byte (2^{7+x})
error_code: 1 byte (0==No Error, &20==Deleted Data; &0E = Data CRC Error)
data: <real_size> bytes
Note that error_code matches the OSWORD &7F result byte
If unreadable:
Track_ID: 1 byte
Head_number: 1 byte
Sector_ID: 1 byte
reported_size: 1 byte
Decoding of the "creator" 5 byte field:
=======================================
(byte1 byte2 byte3 byte4 byte5)
Date_DD = (byte1 AND &F8)/8
Date_MM = (byte3 AND &0F)
Date_YYYY = (byte1 AND &07)*256+byte2
Creator_ID = (byte3 AND &F0)/16
Release_num = ((byte5 AND &C0)/64)*256 + byte4
*********************************************************************/
fsd_format::fsd_format()
{
}
const char *fsd_format::name() const
{
return "fsd";
}
const char *fsd_format::description() const
{
return "BBC Micro 8271 protected disk image";
}
const char *fsd_format::extensions() const
{
return "fsd";
}
bool fsd_format::supports_save() const
{
return false;
}
int fsd_format::identify(io_generic *io, UINT32 form_factor)
{
UINT8 h[3];
io_generic_read(io, h, 0, 3);
if (memcmp(h, "FSD", 3) == 0) {
return 100;
}
return 0;
}
bool fsd_format::load(io_generic *io, UINT32 form_factor, floppy_image *image)
{
UINT64 size = io_generic_size(io);
dynamic_buffer img(size);
io_generic_read(io, &img[0], 0, size);
UINT64 pos;
std::string title;
for(pos=8; pos < size && img[pos] != '\0'; pos++)
title += char(img[pos]);
pos++;
if(pos >= size)
return false;
//popmessage("Loading image of '%s'\n", title);
desc_pc_sector sects[10];
UINT8 total_tracks = img[pos++];
UINT8 tnum, hnum, snum, ssize, error;
hnum = 0;
//osd_printf_verbose("%d Tracks\n", total_tracks+1);
//osd_printf_verbose("Tr.# No.S Sec.# Tr.ID Head# SecID IDsiz REsiz Error\n");
for(int curr_track=0; curr_track <= total_tracks; curr_track++)
{
UINT8 track = img[pos++];
UINT8 spt = img[pos++];
//osd_printf_verbose("%x %x\n", track, spt);
if (spt > 0) // formatted
{
UINT8 readable = img[pos++];
for (int i = 0; i < spt; i++)
{
tnum = img[pos++]; // logical track
hnum = img[pos++]; // head number
snum = img[pos++]; // logical sector
ssize = img[pos++]; // reported size
sects[i].track = tnum;
sects[i].head = hnum;
sects[i].sector = snum;
sects[i].size = ssize;
if (readable == 0xff)
{
sects[i].actual_size = 1 << (img[pos++] + 7);
error = img[pos++];
sects[i].deleted = (error & 0x20) == 0x20;
sects[i].bad_crc = (error & 0x0e) == 0x0e;
sects[i].data = &img[pos];
pos += sects[i].actual_size;
//osd_printf_verbose("Read %x %x %x %x %x %x %x\n", i, sects[i].track, sects[i].head, sects[i].sector, sects[i].size, sects[i].actual_size, error);
}
else
{
throw emu_fatalerror("fsd_format: Unsupported unreadable sector on track %d sector %d head %d", track, i, hnum);
// Unreadable sectors not supported!!
//sects[i].track = track;
//sects[i].head = 0;
//sects[i].sector = i;
//sects[i].size = 0;
//sects[i].actual_size = 0;
//sects[i].deleted = false;
//sects[i].bad_crc = false;
//sects[i].data = nullptr;
//osd_printf_verbose("Unread %x %x %x %x %x %x %x\n", i, sects[i].track, sects[i].head, sects[i].sector, sects[i].size, sects[i].actual_size, 0);
}
}
}
else // unformatted
{
sects[0].track = curr_track;
sects[0].head = hnum;
sects[0].sector = 0;
sects[0].size = 0;
//osd_printf_verbose("Unform %x %x %x %x %x %x %x\n", 0, sects[0].track, sects[0].head, sects[0].sector, sects[0].size, sects[0].actual_size, 0);
}
build_wd_track_fm(curr_track, hnum, image, 50000, spt, sects, 10, 40, 10);
}
return true;
}
const floppy_format_type FLOPPY_FSD_FORMAT = &floppy_image_format_creator<fsd_format>;
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