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ADL: Refactor disk image handling
This commit is contained in:
Walter van Niftrik
parent
9f479c9b17
commit
23870196f5
@ -28,25 +28,9 @@
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namespace Adl {
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static Common::SeekableReadStream *readImage(const Common::String &filename) {
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Common::File *f = new Common::File;
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if (!f->open(filename)) {
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delete f;
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return nullptr;
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}
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return f;
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}
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static bool detectDOS33_NIB(const Common::String &filename) {
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Common::File f;
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if (!f.open(filename))
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error("Failed to open '%s'", filename.c_str());
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static bool detectDOS33_NIB(Common::SeekableReadStream &f) {
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if (f.size() != 232960)
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error("Unrecognized NIB image '%s' of size %d bytes", filename.c_str(), f.size());
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return false;
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uint count = 0;
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uint dos32 = 0, dos33 = 0;
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@ -58,7 +42,7 @@ static bool detectDOS33_NIB(const Common::String &filename) {
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window |= f.readByte();
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if (f.err() || f.eos())
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error("Failed to read '%s'", filename.c_str());
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return false;
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if (window == 0xd5aa96)
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++dos33;
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@ -66,13 +50,51 @@ static bool detectDOS33_NIB(const Common::String &filename) {
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++dos32;
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}
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f.close();
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return dos33 > dos32;
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}
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const uint trackLen = 256 * 26;
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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) {
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uint z = trackLen - (pos % trackLen);
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if (z < size) {
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memcpy(outBuf, inBuf + (pos % trackLen), z);
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memcpy(outBuf + z, inBuf, size - z);
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} else
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memcpy(outBuf, inBuf + (pos % trackLen), size);
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pos += size;
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byte oldVal = 0;
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for (uint n = 0; n < size; ++n) {
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// expand
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assert(outBuf[n] >= minNibble); // corrupt file (TODO: assert?)
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if (outBuf[n] == 0xd5) {
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// Early end of block.
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pos -= (size - n);
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warning("NIB: early end of block @ %x (%d, %d)", n, track, sector);
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return false;
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}
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byte val = lookup[outBuf[n] - minNibble];
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if (val == 0x40) {
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// Badly-encoded nibbles, stop trying to decode here.
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pos -= (size - n);
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warning("NIB: bad nibble %02x @ %x (%d, %d)", outBuf[n], n, track, sector);
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return false;
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}
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// undo checksum
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oldVal = val ^ oldVal;
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outBuf[n] = oldVal;
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}
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byte checksum = inBuf[pos++ % trackLen];
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if (checksum < minNibble || oldVal != lookup[checksum - minNibble]) {
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warning("NIB: checksum mismatch @ (%d, %d)", track, sector);
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return false;
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}
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return true;
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}
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// 4-and-4 encoding (odd-even)
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static uint8 read44(byte *buffer, uint &pos) {
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// 1s in the other fields, so we can just AND
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@ -80,17 +102,14 @@ static uint8 read44(byte *buffer, uint &pos) {
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return ((ret << 1) | 1) & buffer[pos++ % trackLen];
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}
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static Common::SeekableReadStream *readImage_NIB(const Common::String &filename, bool dos33) {
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Common::File f;
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if (!f.open(filename))
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static Common::SeekableReadStream *readImage_NIB(Common::File &f, bool dos33) {
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if (f.size() != 232960) {
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warning("NIB: image '%s' has invalid size of %d bytes", f.getName(), f.size());
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return nullptr;
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}
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if (f.size() != 232960)
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error("Unrecognized NIB image '%s' of size %d bytes", filename.c_str(), f.size());
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// starting at 0xaa, 32 is invalid (see below)
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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 };
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// starting at 0xaa, 64 is invalid (see below)
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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 };
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// starting at 0x96, 64 is invalid (see below)
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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 };
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@ -132,12 +151,10 @@ static Common::SeekableReadStream *readImage_NIB(const Common::String &filename,
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// We should always find the address field first.
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if (prologue != (dos33 ? 0x96 : 0xb5)) {
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// Accept a DOS 3.3(?) header at the start.
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if (prologue == (dos33 ? 0xb5 : 0x96) || prologue == 0xad || prologue == 0xfd) {
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sawAddress = false;
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continue;
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} else {
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error("unknown NIB field prologue %02x", prologue);
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}
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if (prologue != (dos33 ? 0xb5 : 0x96) && prologue != 0xad && prologue != 0xfd)
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warning("NIB: unknown field prologue %02x", prologue);
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sawAddress = false;
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continue;
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}
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volNo = read44(buffer, pos);
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@ -145,7 +162,7 @@ static Common::SeekableReadStream *readImage_NIB(const Common::String &filename,
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sector = read44(buffer, pos);
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uint8 checksum = read44(buffer, pos);
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if ((volNo ^ track ^ sector) != checksum) {
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warning("invalid NIB checksum (volNo %d, track %d, sector %d)", volNo, track, sector);
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warning("NIB: invalid checksum (volNo %d, track %d, sector %d)", volNo, track, sector);
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sawAddress = false;
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continue;
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}
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@ -175,34 +192,10 @@ static Common::SeekableReadStream *readImage_NIB(const Common::String &filename,
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sector = raw2dos[sector];
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output = diskImage + (track * sectorsPerTrack + sector) * bytesPerSector;
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// 6-and-2 uses 342 on-disk bytes
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byte inbuffer[342];
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uint z = trackLen - (pos % trackLen);
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if (z < 342) {
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memcpy(inbuffer, buffer + (pos % trackLen), z);
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memcpy(inbuffer + z, buffer, 342 - z);
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} else
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memcpy(inbuffer, buffer + (pos % trackLen), 342);
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pos += 342;
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byte oldVal = 0;
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for (uint n = 0; n < 342; ++n) {
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// expand
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assert(inbuffer[n] >= 0x96); // corrupt file (TODO: assert?)
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byte val = c_6and2_lookup[inbuffer[n] - 0x96];
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if (val == 0x40) {
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error("NIB: invalid nibble value %02x", inbuffer[n]);
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}
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// undo checksum
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oldVal = val ^ oldVal;
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inbuffer[n] = oldVal;
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}
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byte checksum = buffer[pos++ % trackLen];
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if (checksum < 0x96 || oldVal != c_6and2_lookup[checksum - 0x96]) {
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warning("NIB: checksum mismatch @ (%x, %x)", track, sector);
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if (!readSector_NIB(inbuffer, buffer, sizeof(inbuffer), pos, 0x96, c_6and2_lookup, track, sector))
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continue;
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}
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for (uint n = 0; n < 256; ++n) {
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output[n] = inbuffer[86 + n] << 2;
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@ -220,48 +213,10 @@ static Common::SeekableReadStream *readImage_NIB(const Common::String &filename,
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} else {
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// 5-and-3 uses 410 on-disk bytes, decoding to just over 256 bytes
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byte inbuffer[410];
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uint z = trackLen - (pos % trackLen);
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if (z < 410) {
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memcpy(inbuffer, buffer + (pos % trackLen), z);
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memcpy(inbuffer + z, buffer, 410 - z);
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} else
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memcpy(inbuffer, buffer + (pos % trackLen), 410);
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pos += 410;
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bool truncated = false;
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byte oldVal = 0;
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for (uint n = 0; n < 410; ++n) {
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// expand
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assert(inbuffer[n] >= 0xaa); // corrupt file (TODO: assert?)
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if (inbuffer[n] == 0xd5) {
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// Early end of block.
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truncated = true;
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pos -= (410 - n);
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warning("NIB: early end of block @ 0x%x (%x, %x)", f.pos(), track, sector);
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break;
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}
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byte val = c_5and3_lookup[inbuffer[n] - 0xaa];
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if (val == 0x20) {
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// Badly-encoded nibbles, stop trying to decode here.
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truncated = true;
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warning("NIB: bad nibble %02x @ 0x%x (%x, %x)", inbuffer[n], f.pos(), track, sector);
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pos -= (410 - n);
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break;
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}
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// undo checksum
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oldVal = val ^ oldVal;
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inbuffer[n] = oldVal;
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}
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if (truncated)
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if (!readSector_NIB(inbuffer, buffer, sizeof(inbuffer), pos, 0xaa, c_5and3_lookup, track, sector))
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continue;
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byte checksum = buffer[pos++ % trackLen];
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if (checksum < 0xaa || oldVal != c_5and3_lookup[checksum - 0xaa]) {
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warning("NIB: checksum mismatch @ (%x, %x)", track, sector);
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continue;
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}
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// 8 bytes of nibbles expand to 5 bytes
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// so we have 51 of these batches (255 bytes), plus 2 bytes of 'leftover' nibbles for byte 256
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for (uint n = 0; n < 51; ++n) {
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@ -285,6 +240,14 @@ static Common::SeekableReadStream *readImage_NIB(const Common::String &filename,
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}
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bool DiskImage::open(const Common::String &filename) {
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Common::File *f = new Common::File;
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if (!f->open(filename)) {
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warning("Failed to open '%s'", filename.c_str());
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delete f;
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return false;
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}
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Common::String lcName(filename);
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lcName.toLowercase();
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@ -292,27 +255,29 @@ bool DiskImage::open(const Common::String &filename) {
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_tracks = 35;
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_sectorsPerTrack = 16;
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_bytesPerSector = 256;
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_stream = readImage(filename);
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_stream = f;
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} else if (lcName.hasSuffix(".d13")) {
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_tracks = 35;
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_sectorsPerTrack = 13;
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_bytesPerSector = 256;
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_stream = readImage(filename);
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_stream = f;
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} else if (lcName.hasSuffix(".nib")) {
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_tracks = 35;
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if (detectDOS33_NIB(filename))
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if (detectDOS33_NIB(*f))
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_sectorsPerTrack = 16;
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else
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_sectorsPerTrack = 13;
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_bytesPerSector = 256;
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_stream = readImage_NIB(filename, _sectorsPerTrack == 16);
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f->seek(0);
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_stream = readImage_NIB(*f, _sectorsPerTrack == 16);
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delete f;
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} else if (lcName.hasSuffix(".xfd")) {
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_tracks = 40;
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_sectorsPerTrack = 18;
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_bytesPerSector = 128;
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_stream = readImage(filename);
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_stream = f;
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}
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int expectedSize = _tracks * _sectorsPerTrack * _bytesPerSector;
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