Add pattern for Disk Copy 4.2 disk images.

disk/DC42.hexpat

@@ -0,0 +1,106 @@
+// /***************************************************************************
+// Aaru Data Preservation Suite
+// ----------------------------------------------------------------------------
+//
+// Filename       : DC42.hexpat
+// Author(s)      : Natalia Portillo <claunia@claunia.com>
+//
+// Component      : ImHex pattern for parsing DiskCopy 4.2 disk images.
+// Version        : 1.00
+//
+// --[ Description ] ----------------------------------------------------------
+//
+//     Parses Disk Copy 4.2 disk images.
+//
+// --[ History ] --------------------------------------------------------------
+//     
+//     1.00: Initial release.
+//
+// --[ License ] --------------------------------------------------------------
+//
+//     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 3 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, see <http://www.gnu.org/licenses/>.
+//
+// ----------------------------------------------------------------------------
+// Copyright © 2011-2025 Natalia Portillo
+// ****************************************************************************/
+
+#pragma author Nat Portillo <claunia@claunia.com>
+#pragma description Disk Copy 4.2 disk images parser (*.dc42)
+#pragma endian big
+
+enum format_t : u8
+{
+    // 3.5", single side, double density, GCR
+    kSonyFormat400K = 0x00,
+    // 3.5", double side, double density, GCR
+    kSonyFormat800K = 0x01,
+    // 3.5", double side, double density, MFM
+    kSonyFormat720K = 0x02,
+    // 3.5", double side, high density, MFM
+    kSonyFormat1440K = 0x03,
+    // 3.5", double side, high density, MFM, 21 sectors/track (aka, Microsoft DMF)
+    kSonyFormat1680K = 0x04,
+    // Defined by Sigma Seven's BLU
+    kSigmaFormatTwiggy = 0x54,
+    // Defined by LisaEm
+    kNotStandardFormat = 0x5D
+};
+
+enum fmt_t : u8
+{
+    // Based on GCR nibble
+    // Always 0x02 for MFM disks
+    // Unknown for Apple HD20
+    
+    // Defined by Sigma Seven's BLU</summary>
+    kSigmaFmtByteTwiggy = 0x01,
+    // 3.5" single side double density GCR and MFM all use same code
+    kSonyFmtByte400K = 0x02,
+    // 3.5" double side double density GCR, 512 bytes/sector, interleave 2:1
+    kSonyFmtByte800K = 0x22,
+    // 3.5" double side double density GCR, 512 bytes/sector, interleave 2:1, incorrect value (but appears on official documentation)
+    kSonyFmtByte800KIncorrect = 0x12,
+    // 3.5" double side double density GCR, ProDOS format, interleave 4:1
+    kSonyFmtByteProDos = 0x24,
+    // Defined by LisaEm
+    kFmtNotStandard = 0x93,
+    // Unformatted sectors
+    kInvalidFmtByte = 0x96,
+    // Used incorrectly by Mac OS X with certaing disk images
+    kMacOSXFmtByte = 0x00
+};
+
+struct dc42_header_t
+{
+    // Pascal string, disk name or "-not a Macintosh disk-", filled with garbage
+    char DiskName[64];
+    // Size of data in bytes (usually sectors*512)
+    u32 DataSize;
+    // Size of tags in bytes (usually sectors*12)
+    u32 TagSize;
+    // Checksum of data bytes
+    u32 DataChecksum;
+    // Checksum of tag bytes
+    u32 TagChecksum;
+    // Format of disk, see constants
+    format_t Format;
+    // Format of sectors, see constants
+    fmt_t FmtByte;
+    // Is disk image valid? always 0x01
+    u8 Valid;
+    // Reserved, always 0x00
+    padding[1];
+};
+
+dc42_header_t header @ 0x00;