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Separate CRC16 IBM and CRC16 CCITT contexts, use cached tables.

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This commit is contained in:
Natalia Portillo
2020-01-04 18:18:20 +00:00
parent 951aa79cce
commit c55d6f8ebb
9 changed files with 923 additions and 437 deletions
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43
DiscImageChef.DiscImages/WCDiskImage/Read.cs
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@@ -55,6 +55,7 @@ namespace DiscImageChef.DiscImages
stream.Read(header, 0, 32);
WCDiskImageFileHeader fheader = Marshal.ByteArrayToStructureLittleEndian<WCDiskImageFileHeader>(header);
DicConsole.DebugWriteLine("d2f plugin",
"Detected WC DISK IMAGE with {0} heads, {1} tracks and {2} sectors per track.",
fheader.heads, fheader.cylinders, fheader.sectorsPerTrack);
@@ -71,6 +72,7 @@ namespace DiscImageChef.DiscImages
imageInfo.CreationTime = imageFilter.GetCreationTime();
imageInfo.LastModificationTime = imageFilter.GetLastWriteTime();
imageInfo.MediaTitle = Path.GetFileNameWithoutExtension(imageFilter.GetFilename());
imageInfo.MediaType = Geometry.GetMediaType(((ushort)imageInfo.Cylinders, (byte)imageInfo.Heads,
(ushort)imageInfo.SectorsPerTrack, 512, MediaEncoding.MFM,
false));
@@ -78,7 +80,8 @@ namespace DiscImageChef.DiscImages
/* buffer the entire disk in memory */
for(int cyl = 0; cyl < imageInfo.Cylinders; cyl++)
{
for(int head = 0; head < imageInfo.Heads; head++) ReadTrack(stream, cyl, head);
for(int head = 0; head < imageInfo.Heads; head++)
ReadTrack(stream, cyl, head);
}
/* if there are extra tracks, read them as well */
@@ -107,8 +110,13 @@ namespace DiscImageChef.DiscImages
}
/* adjust number of cylinders */
if(fheader.extraTracks[0] == 1 || fheader.extraTracks[1] == 1) imageInfo.Cylinders++;
if(fheader.extraTracks[2] == 1 || fheader.extraTracks[3] == 1) imageInfo.Cylinders++;
if(fheader.extraTracks[0] == 1 ||
fheader.extraTracks[1] == 1)
imageInfo.Cylinders++;
if(fheader.extraTracks[2] == 1 ||
fheader.extraTracks[3] == 1)
imageInfo.Cylinders++;
/* read the comment and directory data if present */
if(fheader.extraFlags.HasFlag(ExtraFlag.Comment))
@@ -116,6 +124,7 @@ namespace DiscImageChef.DiscImages
DicConsole.DebugWriteLine("d2f plugin", "Comment present, reading");
byte[] sheaderBuffer = new byte[6];
stream.Read(sheaderBuffer, 0, 6);
WCDiskImageSectorHeader sheader =
Marshal.ByteArrayToStructureLittleEndian<WCDiskImageSectorHeader>(sheaderBuffer);
@@ -133,6 +142,7 @@ namespace DiscImageChef.DiscImages
DicConsole.DebugWriteLine("d2f plugin", "Directory listing present, reading");
byte[] sheaderBuffer = new byte[6];
stream.Read(sheaderBuffer, 0, 6);
WCDiskImageSectorHeader sheader =
Marshal.ByteArrayToStructureLittleEndian<WCDiskImageSectorHeader>(sheaderBuffer);
@@ -145,11 +155,13 @@ namespace DiscImageChef.DiscImages
comments += Encoding.ASCII.GetString(dir);
}
if(comments.Length > 0) imageInfo.Comments = comments;
if(comments.Length > 0)
imageInfo.Comments = comments;
// save some variables for later use
fileHeader = fheader;
wcImageFilter = imageFilter;
return true;
}
@@ -189,9 +201,7 @@ namespace DiscImageChef.DiscImages
return result;
}
/// <summary>
/// Read a whole track and cache it
/// </summary>
/// <summary>Read a whole track and cache it</summary>
/// <param name="stream">The stream to read from</param>
/// <param name="cyl">The cylinder number of the track being read.</param>
/// <param name="head">The head number of the track being read.</param>
@@ -206,30 +216,36 @@ namespace DiscImageChef.DiscImages
/* read the sector header */
byte[] sheaderBuffer = new byte[6];
stream.Read(sheaderBuffer, 0, 6);
WCDiskImageSectorHeader sheader =
Marshal.ByteArrayToStructureLittleEndian<WCDiskImageSectorHeader>(sheaderBuffer);
/* validate the sector header */
if(sheader.cylinder != cyl || sheader.head != head || sheader.sector != sect)
if(sheader.cylinder != cyl ||
sheader.head != head ||
sheader.sector != sect)
throw new
InvalidDataException(string.Format("Unexpected sector encountered. Found CHS {0},{1},{2} but expected {3},{4},{5}",
sheader.cylinder, sheader.head, sheader.sector, cyl, head,
sect));
InvalidDataException(string.
Format("Unexpected sector encountered. Found CHS {0},{1},{2} but expected {3},{4},{5}",
sheader.cylinder, sheader.head, sheader.sector, cyl, head,
sect));
sectorData = new byte[512];
/* read the sector data */
switch(sheader.flag)
{
case SectorFlag.Normal: /* read a normal sector and store it in cache */
stream.Read(sectorData, 0, 512);
sectorCache[(cyl, head, sect)] = sectorData;
Crc16Context.Data(sectorData, 512, out crc);
CRC16IBMContext.Data(sectorData, 512, out crc);
calculatedCRC = (short)((256 * crc[0]) | crc[1]);
/*
DicConsole.DebugWriteLine("d2f plugin", "CHS {0},{1},{2}: Regular sector, stored CRC=0x{3:x4}, calculated CRC=0x{4:x4}",
cyl, head, sect, sheader.crc, 256 * crc[0] + crc[1]);
*/
badSectors[(cyl, head, sect)] = sheader.crc != calculatedCRC;
if(calculatedCRC != sheader.crc)
DicConsole.DebugWriteLine("d2f plugin",
"CHS {0},{1},{2}: CRC mismatch: stored CRC=0x{3:x4}, calculated CRC=0x{4:x4}",
@@ -249,7 +265,8 @@ namespace DiscImageChef.DiscImages
DicConsole.DebugWriteLine("d2f plugin", "CHS {0},{1},{2}: RepeatByte sector, fill byte 0x{0:x2}",
cyl, head, sect, sheader.crc & 0xff);
*/
for(int i = 0; i < 512; i++) sectorData[i] = (byte)(sheader.crc & 0xff);
for(int i = 0; i < 512; i++)
sectorData[i] = (byte)(sheader.crc & 0xff);
sectorCache[(cyl, head, sect)] = sectorData;
badSectors[(cyl, head, sect)] = false;