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-rw-r--r--engines/adl/disk.cpp153
-rw-r--r--engines/adl/disk.h16
2 files changed, 169 insertions, 0 deletions
diff --git a/engines/adl/disk.cpp b/engines/adl/disk.cpp
index 22a7d7a431..1ec121831c 100644
--- a/engines/adl/disk.cpp
+++ b/engines/adl/disk.cpp
@@ -63,6 +63,159 @@ bool DiskImage_DSK::open(const Common::String &filename) {
return true;
}
+const DataBlockPtr DiskImage_NIB::getDataBlock(uint track, uint sector, uint offset, uint size) const {
+ return Common::SharedPtr<DiskImage::DataBlock>(new DiskImage::DataBlock(this, track, sector, offset, size));
+}
+
+Common::SeekableReadStream *DiskImage_NIB::createReadStream(uint track, uint sector, uint offset, uint size) const {
+ _memStream->seek((track * _sectorsPerTrack + sector) * _bytesPerSector + offset);
+ Common::SeekableReadStream *stream = _memStream->readStream(size * _bytesPerSector + _bytesPerSector - offset);
+
+ if (_memStream->eos() || _memStream->err())
+ error("Error reading NIB image");
+
+ return stream;
+}
+
+// 4-and-4 encoding (odd-even)
+static uint8 read44(Common::SeekableReadStream *f) {
+ // 1s in the other fields, so we can just AND
+ uint8 ret = f->readByte();
+ return ((ret << 1) | 1) & f->readByte();
+}
+
+bool DiskImage_NIB::open(const Common::String &filename) {
+ assert(!_f->isOpen());
+
+ if (!_f->open(filename))
+ return false;
+
+ uint filesize = _f->size();
+ switch (filesize) {
+ case 232960:
+ _tracks = 35;
+ _sectorsPerTrack = 13;
+ _bytesPerSector = 256;
+ break;
+ default:
+ error("Unrecognized NIB image '%s' of size %d bytes", filename.c_str(), filesize);
+ }
+
+ // starting at 0xaa, 32 is invalid (see below)
+ const byte c_5and3_lookup[] = { 32, 0, 32, 1, 2, 3, 32, 32, 32, 32, 32, 4, 5, 6, 32, 32, 7, 8, 32, 9, 10, 11, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 12, 13, 32, 32, 14, 15, 32, 16, 17, 18, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 19, 20, 32, 21, 22, 23, 32, 32, 32, 32, 32, 24, 25, 26, 32, 32, 27, 28, 32, 29, 30, 31 };
+
+ uint32 diskSize = _tracks * _sectorsPerTrack * _bytesPerSector;
+ byte *diskImage = (byte *)calloc(diskSize, 1);
+ _memStream = new Common::MemoryReadStream(diskImage, diskSize, DisposeAfterUse::YES);
+
+ bool sawAddress = false;
+ uint8 volNo, track, sector;
+
+ while (_f->pos() < _f->size()) {
+ // Read until we find two sync bytes.
+ if (_f->readByte() != 0xd5 || _f->readByte() != 0xaa)
+ continue;
+
+ byte prologue = _f->readByte();
+
+ if (sawAddress && prologue == 0xb5) {
+ warning("NIB: data for %02x/%02x/%02x missing", volNo, track, sector);
+ sawAddress = false;
+ }
+
+ if (!sawAddress) {
+ sawAddress = true;
+
+ // We should always find the address field first.
+ if (prologue != 0xb5) {
+ // Accept a DOS 3.3(?) header at the start.
+ if (_f->pos() == 3 || prologue == 0x96) {
+ // But skip it.
+ _f->skip(20);
+ sawAddress = false;
+ continue;
+ } else {
+ error("unknown NIB field prologue %02x", prologue);
+ }
+ }
+
+ volNo = read44(_f);
+ track = read44(_f);
+ sector = read44(_f);
+ uint8 checksum = read44(_f);
+ if ((volNo ^ track ^ sector) != checksum)
+ error("invalid NIB checksum");
+
+ // FIXME: This is a hires0/hires2-specific hack.
+ if (sector == 1)
+ sector = 2;
+ else if (sector == 2)
+ sector = 1;
+
+ // Epilogue is de/aa plus a gap, but we don't care.
+ } else {
+ sawAddress = false;
+
+ // We should always find the data field after an address field.
+ // TODO: we ignore volNo?
+ byte *output = diskImage + (track * _sectorsPerTrack + sector) * _bytesPerSector;
+
+ // 5-and-3 uses 410 on-disk bytes, decoding to just over 256 bytes
+ byte inbuffer[410];
+ _f->read(inbuffer, 410);
+
+ bool truncated = false;
+ byte oldVal = 0;
+ for (uint n = 0; n < 410; ++n) {
+ // expand
+ assert(inbuffer[n] >= 0xaa); // corrupt file (TODO: assert?)
+ if (inbuffer[n] == 0xd5) {
+ // Early end of block.
+ truncated = true;
+ _f->seek(-(410 - n), SEEK_CUR);
+ warning("NIB: early end of block @ 0x%x (%x, %x)", _f->pos(), track, sector);
+ break;
+ }
+ byte val = c_5and3_lookup[inbuffer[n] - 0xaa];
+ if (val == 0x20) {
+ // Badly-encoded nibbles, stop trying to decode here.
+ truncated = true;
+ warning("NIB: bad nibble %02x @ 0x%x (%x, %x)", inbuffer[n], _f->pos(), track, sector);
+ _f->seek(-(410 - n), SEEK_CUR);
+ break;
+ }
+ // undo checksum
+ oldVal = val ^ oldVal;
+ inbuffer[n] = oldVal;
+ }
+ if (!truncated) {
+ byte checksum = _f->readByte();
+ if (checksum < 0xaa || oldVal != c_5and3_lookup[checksum - 0xaa])
+ warning("NIB: checksum mismatch @ (%x, %x)", track, sector);
+ }
+
+ // 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 true;
+}
+
const DataBlockPtr Files_Plain::getDataBlock(const Common::String &filename, uint offset) const {
return Common::SharedPtr<Files::DataBlock>(new Files::DataBlock(this, filename, offset));
}
diff --git a/engines/adl/disk.h b/engines/adl/disk.h
index 4cab81d720..43b9e387ba 100644
--- a/engines/adl/disk.h
+++ b/engines/adl/disk.h
@@ -125,6 +125,22 @@ public:
Common::SeekableReadStream *createReadStream(uint track, uint sector, uint offset = 0, uint size = 0) const;
};
+// .NIB disk image
+class DiskImage_NIB : public DiskImage {
+public:
+ DiskImage_NIB() : _memStream(nullptr) { }
+ virtual ~DiskImage_NIB() {
+ delete _memStream;
+ }
+
+ bool open(const Common::String &filename);
+ const DataBlockPtr getDataBlock(uint track, uint sector, uint offset = 0, uint size = 0) const;
+ Common::SeekableReadStream *createReadStream(uint track, uint sector, uint offset = 0, uint size = 0) const;
+
+private:
+ Common::SeekableReadStream *_memStream;
+};
+
// Data in files contained in Apple DOS 3.3 disk image
class Files_DOS33 : public Files {
public:
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-27 05:09:56 +0000