PC Engine CD-ROM Header Support

SabreTools.Data.Models/PCEngineCDROM/BootSector.cs

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+namespace SabreTools.Data.Models.PCEngineCDROM
+{
+    /// <summary>
+    /// Standard format for the first sector of the CD-ROM header
+    /// This is likely read by the system to verify the disc's authenticity
+    /// </summary>
+    public sealed class BootSector
+    {
+        /// <summary>
+        /// Copyright notice and credits
+        /// </summary>
+        /// <remarks>Shift-JIS format, lines separated by NULL character, ends in NULL</remarks>
+        public byte[] CopyrightString { get; set; } = new byte[806];
+
+        /// <summary>
+        /// HuC6280 machine code, presumably for initialization
+        /// Note that the actual Boot ROM is on the System Card
+        /// </summary>
+        public byte[] BootROM { get; set; } = new byte[432];
+
+        /// <summary>
+        /// Reserved zeroed padding bytes to fill remainder of sector
+        /// </summary>
+        public byte[] Padding { get; set; } = new byte[810];
+    }
+}

SabreTools.Data.Models/PCEngineCDROM/Constants.cs

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+namespace SabreTools.Data.Models.PCEngineCDROM
+{
+    /// <summary>
+    /// PC Engine CDROM constant values and arrays
+    /// </summary>
+    public static class Constants
+    {
+        /// <summary>
+        /// Standard block size for PC Engine CDROM disc images
+        /// </summary>
+        public static readonly int SectorSize = 2048;
+
+        /// <summary>
+        /// Start of a PC Engine CDROM Header
+        /// </summary>
+        public static readonly byte[] MagicBytes = [0x82, 0xB1, 0x82, 0xCC, 0x83, 0x76, 0x83, 0x8D, 0x83, 0x4F, 0x83, 0x89, 0x83, 0x80, 0x82, 0xCC];
+
+        /// <summary>
+        /// Start of an empty CD-ROM pregap sector
+        /// </summary>
+        public static readonly byte[] PregapBytes = [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00];
+    }
+}

SabreTools.Data.Models/PCEngineCDROM/Enums.cs

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+using System;
+
+namespace SabreTools.Data.Models.PCEngineCDROM
+{
+    /// <summary>
+    /// Opening Mode flags
+    /// </summary>
+    [Flags]
+    public enum OpenMode : byte
+    {
+        /// <summary>
+        /// "Data Read to VRAM"
+        /// Bit set if data is to be read to VRAM
+        /// </summary>
+        READ_TO_VRAM = 0x01,
+
+        /// <summary>
+        /// "Data Read to ADPCM Buffer"
+        /// Bit set if data is to be read to the ADPCM buffer
+        /// </summary>
+        READ_TO_ADPCM = 0x02,
+
+        /// <summary>
+        /// "BG Display"
+        /// Bit set if background display is off
+        /// Unset if it should be on
+        /// </summary>
+        DISPLAY_OFF = 0x20,
+
+        /// <summary>
+        /// "ADPCM Play"
+        /// Bit set if ADPCM should not play
+        /// Unset if it should play
+        /// </summary>
+        ADCPM_DISABLED = 0x40,
+
+        /// <summary>
+        /// "ADPCM Play Mode"
+        /// Bit set if ADPCM should play on repeat
+        /// Unset if it should play only once
+        /// </summary>
+        ADPCM_REPEAT = 0x80,
+
+        /// <summary>
+        /// Mask for bits that are reserved
+        /// </summary>
+        RESERVED_MASK = 0x1C,
+    }
+}

SabreTools.Data.Models/PCEngineCDROM/Header.cs

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+namespace SabreTools.Data.Models.PCEngineCDROM
+{
+    /// <summary>
+    /// This is the standard header of PC Engine CD-ROM
+    /// Located at the first non-zero user data sector of the first data track
+    /// </summary>
+    public sealed class Header
+    {
+        /// <summary>
+        /// Standard sector of data to verify the disc
+        /// </summary>
+        public BootSector BootSector { get; set; } = new();
+
+        /// <summary>
+        /// Initial Program Loader for the PC Engine
+        /// </summary>
+        public IPL IPL { get; set; } = new();
+    }
+}

SabreTools.Data.Models/PCEngineCDROM/IPL.cs

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+using SabreTools.Numerics;
+
+namespace SabreTools.Data.Models.PCEngineCDROM
+{
+    /// <summary>
+    /// IPL (Initial Program Loader) Block Data Format
+    /// Format information from the Hu7 CD System BIOS Manual "CD-ROM BIOS Ver1.00"
+    /// </summary>
+    public sealed class IPL
+    {
+        /// <summary>
+        /// "Load Start Record Number of CD"
+        /// "Top record no. where the program is contained"
+        /// The offset (entry point) of the initial start up program machine code
+        /// </summary>
+        /// <remarks>Big-Endian</remarks>
+        public UInt24 IPLBLK { get; set; } = new();
+
+        /// <summary>
+        /// "Load Block Length of CD"
+        /// "No. of records for program to read"
+        /// Number of sectors to read for the start up program, from the entry point
+        /// </summary>
+        public byte IPLBLN { get; set; }
+
+        /// <summary>
+        /// "Program Load Address"
+        /// "Main memory address for program read"
+        /// Address for where the program code should be placed into memory
+        /// </summary>
+        /// <remarks>Little-Endian</remarks>
+        public ushort IPLSTA { get; set; }
+
+        /// <summary>
+        /// "Program Execute Address"
+        /// "Starting address of execution after program read"
+        /// Address for where the program code should be executed from memory, after reading
+        /// </summary>
+        /// <remarks>Little-Endian</remarks>
+        public ushort IPLJMP { get; set; }
+
+        /// <summary>
+        /// "IPL Set MPR2-6 (+ max_mapping)"
+        /// "Bank no. to set to MPR before program read"
+        /// "When calling BIOS or using interrupt routine from BIOS, MPR0,1,7 cannot be changed"
+        /// Memory Page Register
+        /// MPR0 (I/O, $0000 to $1FFF)
+        /// MPR1 (WORK RAM, $2000 to $3FFF)
+        /// MPR2-6 (USER AREA, $4000 to $5FFF, ..., $C000 to $DFFF)
+        /// MPR7 (BIOS ROM, $E000 to $FFFF)
+        /// </summary>
+        public byte[] IPLMPR { get; set; } = new byte[5];
+
+        /// <summary>
+        /// "Opening mode"
+        /// </summary>
+        public OpenMode OpenMode { get; set; }
+
+        /// <summary>
+        /// "Opening Graphic Data Record Number"
+        /// "Specifies the top record of data to load"
+        /// </summary>
+        /// <remarks>Big-Endian</remarks>
+        public UInt24 GRPBLK { get; set; } = new();
+
+        /// <summary>
+        /// "Opening Graphic Data Length"
+        /// "Specifies the total record that contains color palette data, BAT data, and BG font data"
+        /// </summary>
+        public byte GRPBLN { get; set; }
+
+        /// <summary>
+        /// "Opening Graphic Data Read Address"
+        /// "Specifies the top VRAM address into which BG font data is read"
+        /// </summary>
+        /// <remarks>Little-Endian</remarks>
+        public ushort GRPADR { get; set; }
+
+        /// <summary>
+        /// "Opening ADPCM Data Record Number"
+        /// "Specifies the top record of data to load"
+        /// </summary>
+        /// <remarks>Big-Endian</remarks>
+        public UInt24 ADPBLK { get; set; } = new();
+
+        /// <summary>
+        /// "Opening ADPCM Data Length"
+        /// "Specifies the number of ADPCM data record"
+        /// </summary>
+        public byte ADPBLN { get; set; }
+
+        /// <summary>
+        /// "Opening ADPCM Sampling Rate"
+        /// "Specifies the ADPCM sampling rate"
+        /// </summary>
+        public byte ADPRATE { get; set; }
+
+        /// <summary>
+        /// Reserved bytes, zeroed
+        /// </summary>
+        /// <remarks>7 bytes</remarks>
+        public byte[] Reserved { get; set; } = new byte[7];
+
+        /// <summary>
+        /// "ID String"
+        /// Null-terminated ASCII string
+        /// "PC Engine CD-ROM SYSTEM\0"
+        /// </summary>
+        /// <remarks>24 bytes, NULL terminated</remarks>
+        public byte[] SystemString { get; set; } = new byte[24];
+
+        /// <summary>
+        /// Null-terminated ASCII string
+        /// "Copyright HUDSON SOFT / NEC Home Electronics,Ltd.\0"
+        /// </summary>
+        /// <remarks>50 bytes, NULL terminated</remarks>
+        public byte[] CopyrightString { get; set; } = new byte[50];
+
+        /// <summary>
+        /// "Program Name"
+        /// ASCII string, not null-terminated
+        /// </summary>
+        /// <remarks>16 bytes, padding with trailing SPACE \x20</remarks>
+        public byte[] ProgramName { get; set; } = new byte[16];
+
+        /// <summary>
+        /// Additional optional string
+        /// ASCII string, not null-terminated
+        /// </summary>
+        /// <remarks>6 bytes, padding with trailing SPACE \x20</remarks>
+        public byte[] AdditionalString { get; set; } = new byte[16];
+    }
+}

SabreTools.Serialization.Readers.Test/PCEngineCDROMTests.cs

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+using System.IO;
+using System.Linq;
+using Xunit;
+
+namespace SabreTools.Serialization.Readers.Test
+{
+    public class PCEngineCDROMTests
+    {
+        [Fact]
+        public void NullArray_Null()
+        {
+            byte[]? data = null;
+            int offset = 0;
+            var deserializer = new PCEngineCDROM();
+
+            var actual = deserializer.Deserialize(data, offset);
+            Assert.Null(actual);
+        }
+
+        [Fact]
+        public void EmptyArray_Null()
+        {
+            byte[]? data = [];
+            int offset = 0;
+            var deserializer = new PCEngineCDROM();
+
+            var actual = deserializer.Deserialize(data, offset);
+            Assert.Null(actual);
+        }
+
+        [Fact]
+        public void InvalidArray_Null()
+        {
+            byte[]? data = [.. Enumerable.Repeat<byte>(0xFF, 1024)];
+            int offset = 0;
+            var deserializer = new PCEngineCDROM();
+
+            var actual = deserializer.Deserialize(data, offset);
+            Assert.Null(actual);
+        }
+
+        [Fact]
+        public void NullStream_Null()
+        {
+            Stream? data = null;
+            var deserializer = new PCEngineCDROM();
+
+            var actual = deserializer.Deserialize(data);
+            Assert.Null(actual);
+        }
+
+        [Fact]
+        public void EmptyStream_Null()
+        {
+            Stream? data = new MemoryStream([]);
+            var deserializer = new PCEngineCDROM();
+
+            var actual = deserializer.Deserialize(data);
+            Assert.Null(actual);
+        }
+
+        [Fact]
+        public void InvalidStream_Null()
+        {
+            Stream? data = new MemoryStream([.. Enumerable.Repeat<byte>(0xFF, 1024)]);
+            var deserializer = new PCEngineCDROM();
+
+            var actual = deserializer.Deserialize(data);
+            Assert.Null(actual);
+        }
+    }
+}