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#44: Detect sector order, ignore extension (lots of invalid PO images that are not prodos-ordered!)

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Brendan Robert 2024-07-10 12:42:07 -05:00
parent 4c6a8f976c
commit 9769f3282a
1 changed files with 44 additions and 5 deletions
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49
src/main/java/jace/hardware/FloppyDisk.java
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@ -103,6 +103,14 @@ public class FloppyDisk {
// This constructor is only used for disk conversion...
}
public static enum SectorOrder {
DOS(DOS_33_SECTOR_ORDER), PRODOS(PRODOS_SECTOR_ORDER), UNKNOWN(DOS_33_SECTOR_ORDER);
public final int[] sectors;
SectorOrder(int[] sectors) {
this.sectors = sectors;
}
}
/**
*
* @param diskFile
@ -110,17 +118,17 @@ public class FloppyDisk {
*/
public FloppyDisk(File diskFile) throws IOException {
FileInputStream input = new FileInputStream(diskFile);
String name = diskFile.getName().toUpperCase();
readDisk(input, name.endsWith(".PO"));
readDisk(input);
writeProtected = !diskFile.canWrite();
diskPath = diskFile;
}
// brendanr: refactored to use input stream
public void readDisk(InputStream diskFile, boolean prodosOrder) throws IOException {
public void readDisk(InputStream diskFile) throws IOException {
isNibblizedImage = true;
volumeNumber = CardDiskII.DEFAULT_VOLUME_NUMBER;
headerLength = 0;
SectorOrder sectorOrder = SectorOrder.UNKNOWN;
try {
int bytesRead = diskFile.read(nibbles);
if (bytesRead == DISK_2MG_NIB_LENGTH) {
@ -134,13 +142,22 @@ public class FloppyDisk {
if (bytesRead == DISK_2MG_NON_NIB_LENGTH) {
bytesRead -= 0x040;
// Try to pick up correct sector ordering and volume from 2MG header.
prodosOrder = (nibbles[12] == 01);
if (nibbles[12] == 01) {
sectorOrder = SectorOrder.PRODOS;
} else {
sectorOrder = SectorOrder.DOS;
}
volumeNumber = ((nibbles[17] & 1) == 1) ? nibbles[16] : 254;
nibbles = Arrays.copyOfRange(nibbles, 0x040, nibbles.length);
headerLength = 0x040;
}
currentSectorOrder = prodosOrder ? PRODOS_SECTOR_ORDER : DOS_33_SECTOR_ORDER;
if (sectorOrder == SectorOrder.UNKNOWN) {
sectorOrder = detectSectorOrder(nibbles, SectorOrder.DOS);
}
System.out.println(null == sectorOrder ? "Sector order is null" : "Sector order is " + sectorOrder.name());
currentSectorOrder = sectorOrder.sectors;
if (bytesRead == DISK_PLAIN_LENGTH) {
isNibblizedImage = false;
nibbles = nibblize(nibbles);
@ -157,6 +174,28 @@ public class FloppyDisk {
StateManager.markDirtyValue(currentSectorOrder);
}
private SectorOrder detectSectorOrder(byte[] nibbles, SectorOrder defaultOrder) {
// Easiest way to tell sector order is see if we can parse a prodos volume at block 2
int offset = 0x0400;
SectorOrder result = defaultOrder;
// First two bytes are zero (no previous block)
if (nibbles[offset] != 0 || nibbles[offset+1] != 0) {
return result;
}
// Next two bytes are either both zero or at least in the range of 3...280
int nextBlock = (nibbles[offset+2] & 0x0ff) | (nibbles[offset+3] << 8);
if (nextBlock == 1 || nextBlock == 2 || nextBlock > 280) {
return result;
}
// Now check total blocks at offset 0x29
int totalBlocks = (nibbles[offset+0x29] & 0x0ff) | (nibbles[offset+0x2a] << 8);
if (totalBlocks != 280) {
System.out.println("Prodos detection failed: total blocks is not 280: " + totalBlocks);
return result;
}
System.out.println("This disk appears to be Prodos-ordered.");
return SectorOrder.PRODOS;
}
/*
* Convert a block-format disk to a 6-by-2 nibblized encoding scheme (raw NIB disk format)
*/