ApplePartitionMapReader 1.0.1

ApplePartitionMapReader

ApplePartitionMapReader is a lightweight .NET library for reading Apple Partition Maps from classic Macintosh disk images. It provides a simple, zero-allocation API to detect partition maps, enumerate partitions, and access partition metadata.

Features

• Detect Apple Partition Maps in disk images
• Enumerate all partitions with detailed metadata
• Access partition properties: name, type, start block, block count, status flags
• Strongly-typed status flags with ApplePartitionMapStatus enum
• Zero-allocation API using struct enumerators and span-based operations
• High-performance parsing using stack-allocated buffers

Installation

Install from NuGet:

dotnet add package ApplePartitionMapReader

Or reference the project directly:

dotnet add reference ../src/ApplePartitionMapReader.csproj

Quick Start Example

using ApplePartitionMapReader;

// Open a disk image containing an Apple Partition Map
using var stream = File.OpenRead("disk.iso");

// Check if the stream contains an Apple Partition Map
if (ApplePartitionMap.IsApplePartitionMap(stream, 0))
{
    var map = new ApplePartitionMap(stream, 0);
    
    // Enumerate all partitions (zero allocation)
    foreach (var partition in map)
    {
        Console.WriteLine($"Name: {partition.Name}");
        Console.WriteLine($"Type: {partition.Type}");
        Console.WriteLine($"Start: {partition.PartitionStartBlock}");
        Console.WriteLine($"Size: {partition.PartitionBlockCount} blocks");
        Console.WriteLine($"Status: {partition.StatusFlags}");
        Console.WriteLine();
    }
    
    // Or access by index
    var firstPartition = map[0];
    Console.WriteLine($"First partition: {firstPartition.Name}");
}

Zero-Allocation API

The library is designed for high-performance scenarios with zero heap allocations on the hot path:

Zero-Allocation Enumeration

// The foreach loop uses a struct enumerator - no allocation!
foreach (var partition in map)
{
    // Process partition
}

// Get count without enumerating
int count = map.EntryCount;

Zero-Allocation String Formatting

String16 and String32 types support span-based formatting to avoid string allocations:

Span<char> buffer = stackalloc char[32];
if (partition.Name.TryFormat(buffer, out int charsWritten))
{
    ReadOnlySpan<char> name = buffer[..charsWritten];
    // Use name without allocation
}

// Get length without allocating
int length = partition.Name.Length;

Zero-Allocation String Comparison

Compare partition names/types directly without allocating strings:

// Compare with a string span - no allocation
if (partition.Type.Equals("Apple_HFS".AsSpan()))
{
    // Handle HFS partition
}

// Compare with ASCII bytes
if (partition.Type.Equals("Apple_HFS"u8))
{
    // Handle HFS partition
}

Zero-Allocation Driver Descriptor Map Access

// Use TryGet pattern to avoid nullable struct boxing
if (map.TryGetDriverDescriptorMap(out var ddm))
{
    Console.WriteLine($"Block size: {ddm.BlockSize}");
}

API Overview

ApplePartitionMap

ApplePartitionMapEntry

Represents a single partition in the map with the following properties:

String16 / String32

Fixed-size string types with zero-allocation APIs:

ApplePartitionMapStatus

Flags enum representing partition status:

Common Partition Types

License

MIT License - see LICENSE for details.

Related Projects

• AppleDiskImageReader - Reader for Apple II universal disk (.2mg) images
• AppleIIDiskReader - Reader for Apple II DOS 3.3 disk (.dsk) images
• ProDosVolumeReader - Reader for ProDOS (.po) volumes
• WozDiskImageReader - Reader for WOZ (.woz) disk images
• DiskCopyReader - Reader for Disk Copy 4.2 (.dc42) images
• MfsReader - Reader for MFS (Macintosh File System) volumes
• HfsReader - Reader for HFS (Hierarchical File System) volumes
• ResourceForkReader - Reader for Macintosh resource forks
• BinaryIIReader - Reader for Binary II (.bny, .bxy) archives
• StuffItReader - Reader for StuffIt (.sit) archives
• ShrinkItReader - Reader for ShrinkIt (.shk, .sdk) archives