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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#include "common/stream.h"
#include "common/substream.h"
#include "common/memstream.h"
#include "common/md5.h"
#include "adl/disk.h"
namespace Adl {
const uint trackLen = 256 * 26;
static bool detectDOS33_NIB(Common::SeekableReadStream &f) {
if (f.size() != 232960)
return false;
uint count = 0;
uint dos32 = 0, dos33 = 0;
uint32 window = 0;
while (count++ < trackLen) {
window &= 0xffff;
window <<= 8;
window |= f.readByte();
if (f.err() || f.eos())
return false;
if (window == 0xd5aa96)
++dos33;
else if (window == 0xd5aab5)
++dos32;
}
return dos33 > dos32;
}
static bool readSector_NIB(byte outBuf[], const byte inBuf[], uint size, uint &pos, const byte minNibble, const byte lookup[], const uint track, const uint sector) {
uint z = trackLen - (pos % trackLen);
if (z < size) {
memcpy(outBuf, inBuf + (pos % trackLen), z);
memcpy(outBuf + z, inBuf, size - z);
} else
memcpy(outBuf, inBuf + (pos % trackLen), size);
pos += size;
byte oldVal = 0;
for (uint n = 0; n < size; ++n) {
// expand
assert(outBuf[n] >= minNibble); // corrupt file (TODO: assert?)
if (outBuf[n] == 0xd5) {
// Early end of block.
pos -= (size - n);
warning("NIB: early end of block @ %x (%d, %d)", n, track, sector);
return false;
}
byte val = lookup[outBuf[n] - minNibble];
if (val == 0x40) {
// Badly-encoded nibbles, stop trying to decode here.
pos -= (size - n);
warning("NIB: bad nibble %02x @ %x (%d, %d)", outBuf[n], n, track, sector);
return false;
}
// undo checksum
oldVal = val ^ oldVal;
outBuf[n] = oldVal;
}
byte checksum = inBuf[pos++ % trackLen];
if (checksum < minNibble || oldVal != lookup[checksum - minNibble]) {
warning("NIB: checksum mismatch @ (%d, %d)", track, sector);
return false;
}
return true;
}
// 4-and-4 encoding (odd-even)
static uint8 read44(byte *buffer, uint &pos) {
// 1s in the other fields, so we can just AND
uint8 ret = buffer[pos++ % trackLen];
return ((ret << 1) | 1) & buffer[pos++ % trackLen];
}
static Common::SeekableReadStream *readImage_NIB(Common::File &f, bool dos33, uint tracks = 35) {
if (f.size() != 35 * trackLen) {
warning("NIB: image '%s' has invalid size of %d bytes", f.getName(), f.size());
return nullptr;
}
// starting at 0xaa, 64 is invalid (see below)
const byte c_5and3_lookup[] = { 64, 0, 64, 1, 2, 3, 64, 64, 64, 64, 64, 4, 5, 6, 64, 64, 7, 8, 64, 9, 10, 11, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 12, 13, 64, 64, 14, 15, 64, 16, 17, 18, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 19, 20, 64, 21, 22, 23, 64, 64, 64, 64, 64, 24, 25, 26, 64, 64, 27, 28, 64, 29, 30, 31 };
// starting at 0x96, 64 is invalid (see below)
const byte c_6and2_lookup[] = { 0, 1, 64, 64, 2, 3, 64, 4, 5, 6, 64, 64, 64, 64, 64, 64, 7, 8, 64, 64, 64, 9, 10, 11, 12, 13, 64, 64, 14, 15, 16, 17, 18, 19, 64, 20, 21, 22, 23, 24, 25, 26, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 27, 64, 28, 29, 30, 64, 64, 64, 31, 64, 64, 32, 33, 64, 34, 35, 36, 37, 38, 39, 40, 64, 64, 64, 64, 64, 41, 42, 43, 64, 44, 45, 46, 47, 48, 49, 50, 64, 64, 51, 52, 53, 54, 55, 56, 64, 57, 58, 59, 60, 61, 62, 63 };
const uint sectorsPerTrack = (dos33 ? 16 : 13);
const uint bytesPerSector = 256;
const uint imageSize = tracks * sectorsPerTrack * bytesPerSector;
byte *const diskImage = (byte *)calloc(imageSize, 1);
bool sawAddress = false;
uint8 volNo = 0, track = 0, sector = 0;
byte buffer[trackLen];
uint firstGoodTrackPos = 0;
uint pos = trackLen; // force read
while (true) {
if (pos >= trackLen+firstGoodTrackPos) {
if (f.pos() == (int)(tracks * trackLen))
break;
f.read(buffer, sizeof(buffer));
firstGoodTrackPos = 0;
pos = 0;
sawAddress = false;
}
// Read until we find two sync bytes.
if (buffer[pos++ % trackLen] != 0xd5 || buffer[pos++ % trackLen] != 0xaa)
continue;
byte prologue = buffer[pos++ % trackLen];
if (sawAddress && prologue == (dos33 ? 0x96 : 0xb5)) {
sawAddress = false;
}
if (!sawAddress) {
sawAddress = true;
// We should always find the address field first.
if (prologue != (dos33 ? 0x96 : 0xb5)) {
// Accept a DOS 3.3(?) header at the start.
if (prologue != (dos33 ? 0xb5 : 0x96) && prologue != 0xad && prologue != 0xfd)
warning("NIB: unknown field prologue %02x", prologue);
sawAddress = false;
continue;
}
volNo = read44(buffer, pos);
track = read44(buffer, pos);
sector = read44(buffer, pos);
uint8 checksum = read44(buffer, pos);
if ((volNo ^ track ^ sector) != checksum) {
warning("NIB: invalid checksum (volNo %d, track %d, sector %d)", volNo, track, sector);
sawAddress = false;
continue;
}
if (track >= tracks || sector >= sectorsPerTrack) {
warning("NIB: sector out of bounds @ (%x, %x)", track, sector);
sawAddress = false;
continue;
}
if (!firstGoodTrackPos)
firstGoodTrackPos = pos;
// Epilogue is de/aa plus a gap, but we don't care.
continue;
}
sawAddress = false;
// We should always find the data field after an address field.
// TODO: we ignore volNo?
byte *output = diskImage + (track * sectorsPerTrack + sector) * bytesPerSector;
if (dos33) {
// We hardcode the DOS 3.3 mapping here. TODO: Do we also need raw/prodos?
int raw2dos[16] = { 0, 7, 14, 6, 13, 5, 12, 4, 11, 3, 10, 2, 9, 1, 8, 15 };
sector = raw2dos[sector];
output = diskImage + (track * sectorsPerTrack + sector) * bytesPerSector;
byte inbuffer[342];
if (!readSector_NIB(inbuffer, buffer, sizeof(inbuffer), pos, 0x96, c_6and2_lookup, track, sector))
continue;
for (uint n = 0; n < 256; ++n) {
output[n] = inbuffer[86 + n] << 2;
if (n < 86) { // use first pair of bits
output[n] |= ((inbuffer[n] & 1) << 1);
output[n] |= ((inbuffer[n] & 2) >> 1);
} else if (n < 86*2) { // second pair
output[n] |= ((inbuffer[n-86] & 4) >> 1);
output[n] |= ((inbuffer[n-86] & 8) >> 3);
} else { // third pair
output[n] |= ((inbuffer[n-86*2] & 0x10) >> 3);
output[n] |= ((inbuffer[n-86*2] & 0x20) >> 5);
}
}
} else {
// 5-and-3 uses 410 on-disk bytes, decoding to just over 256 bytes
byte inbuffer[410];
if (!readSector_NIB(inbuffer, buffer, sizeof(inbuffer), pos, 0xaa, c_5and3_lookup, track, sector))
continue;
// 8 bytes of nibbles expand to 5 bytes
// so we have 51 of these batches (255 bytes), plus 2 bytes of 'leftover' nibbles for byte 256
for (uint n = 0; n < 51; ++n) {
// e.g. figure 3.18 of Beneath Apple DOS
byte lowbits1 = inbuffer[51*3 - n];
byte lowbits2 = inbuffer[51*2 - n];
byte lowbits3 = inbuffer[51*1 - n];
byte lowbits4 = (lowbits1 & 2) << 1 | (lowbits2 & 2) | (lowbits3 & 2) >> 1;
byte lowbits5 = (lowbits1 & 1) << 2 | (lowbits2 & 1) << 1 | (lowbits3 & 1);
output[250 - 5*n] = (inbuffer[n + 51*3 + 1] << 3) | ((lowbits1 >> 2) & 0x7);
output[251 - 5*n] = (inbuffer[n + 51*4 + 1] << 3) | ((lowbits2 >> 2) & 0x7);
output[252 - 5*n] = (inbuffer[n + 51*5 + 1] << 3) | ((lowbits3 >> 2) & 0x7);
output[253 - 5*n] = (inbuffer[n + 51*6 + 1] << 3) | lowbits4;
output[254 - 5*n] = (inbuffer[n + 51*7 + 1] << 3) | lowbits5;
}
output[255] = (inbuffer[409] << 3) | (inbuffer[0] & 0x7);
}
}
return new Common::MemoryReadStream(diskImage, imageSize, DisposeAfterUse::YES);
}
bool DiskImage::open(const Common::String &filename) {
Common::File *f = new Common::File;
if (!f->open(filename)) {
warning("Failed to open '%s'", filename.c_str());
delete f;
return false;
}
Common::String lcName(filename);
lcName.toLowercase();
if (lcName.hasSuffix(".dsk")) {
_tracks = 35;
_sectorsPerTrack = 16;
_bytesPerSector = 256;
_stream = f;
} else if (lcName.hasSuffix(".d13")) {
_tracks = 35;
_sectorsPerTrack = 13;
_bytesPerSector = 256;
_stream = f;
} else if (lcName.hasSuffix(".nib")) {
_tracks = 35;
if (detectDOS33_NIB(*f))
_sectorsPerTrack = 16;
else
_sectorsPerTrack = 13;
_bytesPerSector = 256;
f->seek(0);
_stream = readImage_NIB(*f, _sectorsPerTrack == 16);
delete f;
} else if (lcName.hasSuffix(".xfd")) {
_tracks = 40;
_sectorsPerTrack = 18;
_bytesPerSector = 128;
_stream = f;
}
int expectedSize = _tracks * _sectorsPerTrack * _bytesPerSector;
if (!_stream)
return false;
if (_stream->size() != expectedSize)
error("Unrecognized disk image '%s' of size %d bytes (expected %d bytes)", filename.c_str(), _stream->size(), expectedSize);
return true;
}
const DataBlockPtr DiskImage::getDataBlock(uint track, uint sector, uint offset, uint size) const {
return DataBlockPtr(new DiskImage::DataBlock(this, track, sector, offset, size, _sectorLimit));
}
Common::SeekableReadStream *DiskImage::createReadStream(uint track, uint sector, uint offset, uint size, uint sectorLimit) const {
const uint bytesToRead = size * _bytesPerSector + _bytesPerSector - offset;
byte *const data = (byte *)malloc(bytesToRead);
uint dataOffset = 0;
if (sectorLimit == 0)
sectorLimit = _sectorsPerTrack;
if (sector >= sectorLimit)
error("Sector %i is out of bounds for %i-sector reading", sector, sectorLimit);
while (dataOffset < bytesToRead) {
uint bytesRemInTrack = (sectorLimit - 1 - sector) * _bytesPerSector + _bytesPerSector - offset;
_stream->seek((track * _sectorsPerTrack + sector) * _bytesPerSector + offset);
if (bytesToRead - dataOffset < bytesRemInTrack)
bytesRemInTrack = bytesToRead - dataOffset;
if (_stream->read(data + dataOffset, bytesRemInTrack) < bytesRemInTrack)
error("Error reading disk image at track %d; sector %d", track, sector);
++track;
sector = 0;
offset = 0;
dataOffset += bytesRemInTrack;
}
return new Common::MemoryReadStream(data, bytesToRead, DisposeAfterUse::YES);
}
int32 computeMD5(const Common::FSNode &node, Common::String &md5, uint32 md5Bytes) {
Common::File f;
if (!f.open(node))
return -1;
if (node.getName().matchString("*.nib", true) && f.size() == 35 * trackLen) {
uint lastSector = md5Bytes / 256;
uint tracks;
bool isDOS33 = detectDOS33_NIB(f);
if (isDOS33)
tracks = (lastSector / 16) + 1;
else
tracks = (lastSector / 13) + 1;
// Tracks 1 and 2 are swapped in some copy protections, so we read three tracks when two tracks are needed
if (tracks == 2)
tracks = 3;
f.seek(0);
Common::SeekableReadStream *stream = readImage_NIB(f, isDOS33, tracks);
if (stream) {
md5 = Common::computeStreamMD5AsString(*stream, md5Bytes);
delete stream;
return 35 * (isDOS33 ? 16 : 13) * 256;
}
return -1;
} else {
md5 = Common::computeStreamMD5AsString(f, md5Bytes);
return f.size();
}
}
const DataBlockPtr Files_Plain::getDataBlock(const Common::String &filename, uint offset) const {
return Common::SharedPtr<Files::DataBlock>(new Files::DataBlock(this, filename, offset));
}
Common::SeekableReadStream *Files_Plain::createReadStream(const Common::String &filename, uint offset) const {
Common::File *f(new Common::File());
if (!f->open(filename))
error("Failed to open '%s'", filename.c_str());
if (offset == 0)
return f;
else
return new Common::SeekableSubReadStream(f, offset, f->size(), DisposeAfterUse::YES);
}
Files_DOS33::~Files_DOS33() {
delete _disk;
}
Files_DOS33::Files_DOS33() :
_disk(nullptr) {
}
void Files_DOS33::readSectorList(TrackSector start, Common::Array<TrackSector> &list) {
TrackSector index = start;
while (index.track != 0) {
Common::ScopedPtr<Common::SeekableReadStream> stream(_disk->createReadStream(index.track, index.sector));
stream->readByte();
index.track = stream->readByte();
index.sector = stream->readByte();
stream->seek(9, SEEK_CUR);
// This only handles sequential files
TrackSector ts;
ts.track = stream->readByte();
ts.sector = stream->readByte();
while (ts.track != 0) {
list.push_back(ts);
ts.track = stream->readByte();
ts.sector = stream->readByte();
if (stream->err())
error("Error reading sector list");
if (stream->eos())
break;
}
}
}
void Files_DOS33::readVTOC() {
Common::ScopedPtr<Common::SeekableReadStream> stream(_disk->createReadStream(0x11, 0x00));
stream->readByte();
byte track = stream->readByte();
byte sector = stream->readByte();
while (track != 0) {
char name[kFilenameLen + 1] = { };
stream.reset(_disk->createReadStream(track, sector));
stream->readByte();
track = stream->readByte();
sector = stream->readByte();
stream->seek(8, SEEK_CUR);
for (uint i = 0; i < 7; ++i) {
TOCEntry entry;
TrackSector sectorList;
sectorList.track = stream->readByte();
sectorList.sector = stream->readByte();
entry.type = stream->readByte();
stream->read(name, kFilenameLen);
// Convert to ASCII
for (uint j = 0; j < kFilenameLen; j++)
name[j] &= 0x7f;
// Strip trailing spaces
for (int j = kFilenameLen - 1; j >= 0; --j) {
if (name[j] == ' ')
name[j] = 0;
else
break;
}
entry.totalSectors = stream->readUint16BE();
// 0 is empty slot, 255 is deleted file
if (sectorList.track != 0 && sectorList.track != 255) {
readSectorList(sectorList, entry.sectors);
_toc[name] = entry;
}
}
}
}
const DataBlockPtr Files_DOS33::getDataBlock(const Common::String &filename, uint offset) const {
return Common::SharedPtr<Files::DataBlock>(new Files::DataBlock(this, filename, offset));
}
Common::SeekableReadStream *Files_DOS33::createReadStreamText(const TOCEntry &entry) const {
byte *buf = (byte *)malloc(entry.sectors.size() * kSectorSize);
byte *p = buf;
for (uint i = 0; i < entry.sectors.size(); ++i) {
Common::ScopedPtr<Common::SeekableReadStream> stream(_disk->createReadStream(entry.sectors[i].track, entry.sectors[i].sector));
assert(stream->size() == kSectorSize);
while (true) {
byte textChar = stream->readByte();
if (stream->eos() || textChar == 0)
break;
if (stream->err())
error("Error reading text file");
*p++ = textChar;
}
}
return new Common::MemoryReadStream(buf, p - buf, DisposeAfterUse::YES);
}
Common::SeekableReadStream *Files_DOS33::createReadStreamBinary(const TOCEntry &entry) const {
byte *buf = (byte *)malloc(entry.sectors.size() * kSectorSize);
Common::ScopedPtr<Common::SeekableReadStream> stream(_disk->createReadStream(entry.sectors[0].track, entry.sectors[0].sector));
if (entry.type == kFileTypeBinary)
stream->readUint16LE(); // Skip start address
uint16 size = stream->readUint16LE();
uint16 offset = 0;
uint16 sectorIdx = 1;
while (true) {
offset += stream->read(buf + offset, size - offset);
if (offset == size)
break;
if (stream->err())
error("Error reading binary file");
assert(stream->eos());
if (sectorIdx == entry.sectors.size())
error("Not enough sectors for binary file size");
stream.reset(_disk->createReadStream(entry.sectors[sectorIdx].track, entry.sectors[sectorIdx].sector));
++sectorIdx;
}
return new Common::MemoryReadStream(buf, size, DisposeAfterUse::YES);
}
Common::SeekableReadStream *Files_DOS33::createReadStream(const Common::String &filename, uint offset) const {
if (!_toc.contains(filename))
error("Failed to locate '%s'", filename.c_str());
const TOCEntry &entry = _toc[filename];
Common::SeekableReadStream *stream;
switch(entry.type) {
case kFileTypeText:
stream = createReadStreamText(entry);
break;
case kFileTypeAppleSoft:
case kFileTypeBinary:
stream = createReadStreamBinary(entry);
break;
default:
error("Unsupported file type %i", entry.type);
}
return new Common::SeekableSubReadStream(stream, offset, stream->size(), DisposeAfterUse::YES);
}
bool Files_DOS33::open(const Common::String &filename) {
_disk = new DiskImage();
if (!_disk->open(filename))
return false;
readVTOC();
return true;
}
} // End of namespace Adl
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