Add endianness-aware BinaryReader/BinaryWriter extensions; bump PolyShim to 2.12.1

[Copilot]

Adds explicit big-endian and little-endian read/write extension methods for BinaryReader and BinaryWriter backed by System.Buffers.Binary.BinaryPrimitives. Also updates PolyShim to 2.12.2, which introduces the BinaryPrimitives polyfill for older target frameworks.

Changes

• Directory.Packages.props — PolyShim 2.11.0 → 2.12.1
• BinaryReaderExtensions — 16 new methods: ReadInt16/UInt16/Int32/UInt32/Int64/UInt64/Single/DoubleBigEndian|LittleEndian
• BinaryWriterExtensions — 16 matching WriteInt16/UInt16/Int32/UInt32/Int64/UInt64/Single/DoubleBigEndian|LittleEndian methods
• Float/double methods are gated on #if NET5_0_OR_GREATER || !FEATURE_MEMORY — BinaryPrimitives overloads for float/double were added in .NET 5 and aren't present in System.Memory 4.6.3 (used by net462/netstandard2.0); they are available natively on .NET 5+ and via PolyShim on net35

Usage

// Read a big-endian int from a stream regardless of host byte order
using var reader = new BinaryReader(stream);
int magic = reader.ReadInt32BigEndian();

// Write a little-endian ulong
using var writer = new BinaryWriter(stream);
writer.WriteUInt64LittleEndian(0xDEADBEEFCAFEBABEuL);

[codecov]

Codecov Report

❌ Patch coverage is 97.61905% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.13%. Comparing base (560c9ce) to head (a934c52).

Files with missing lines	Patch %	Lines
PowerKit/Extensions/BinaryReaderExtensions.cs	90.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##            prime      #91      +/-   ##
==========================================
+ Coverage   86.43%   87.13%   +0.69%     
==========================================
  Files          75       75              
  Lines        1268     1352      +84     
  Branches      235      236       +1     
==========================================
+ Hits         1096     1178      +82     
- Misses        121      122       +1     
- Partials       51       52       +1     

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[Copilot]

Pull request overview

This PR adds explicit endianness-aware read/write extension methods for BinaryReader/BinaryWriter using System.Buffers.Binary.BinaryPrimitives, and bumps PolyShim to support older target frameworks via a BinaryPrimitives polyfill.

Changes:

• Add Read*BigEndian/Read*LittleEndian methods for integers (and conditionally for float/double) on BinaryReader.
• Add matching Write*BigEndian/Write*LittleEndian methods on BinaryWriter.
• Add comprehensive unit tests for the new APIs and bump PolyShim from 2.11.0 to 2.12.1.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
PowerKit/Extensions/BinaryWriterExtensions.cs	Adds big-/little-endian primitive write helpers using BinaryPrimitives.
PowerKit/Extensions/BinaryReaderExtensions.cs	Adds big-/little-endian primitive read helpers using BinaryPrimitives.
PowerKit.Tests/Extensions/BinaryWriterExtensionsTests.cs	Adds byte-level assertions for all new writer methods.
PowerKit.Tests/Extensions/BinaryReaderExtensionsTests.cs	Adds value-level assertions for all new reader methods.
Directory.Packages.props	Updates PolyShim dependency to 2.12.1.

---

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[Tyrrrz]

@copilot if you update PolyShim to 2.12.2, you can drop the #if guards on the float/double overloads

[Copilot]

@copilot if you update PolyShim to 2.12.2, you can drop the #if guards on the float/double overloads

Done — bumped PolyShim to 2.12.2 and removed the #if guards from both BinaryReaderExtensions and BinaryWriterExtensions. The float/double overloads now compile unconditionally across all TFMs.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (4)

PowerKit/Extensions/BinaryReaderExtensions.cs:154

• These float read helpers call BinaryPrimitives.ReadSingle*Endian. This repo targets netstandard2.0/net462 (see PowerKit.csproj), and the PR description notes these float/double BinaryPrimitives overloads aren’t available on all target frameworks (e.g., when using System.Memory 4.6.3). Consider implementing float/double endianness via BitConverter + conditional Array.Reverse so the methods compile consistently across TFMs.

        /// <summary>
        /// Reads a 4-byte floating-point value from the stream using big-endian byte order.
        /// </summary>
        public float ReadSingleBigEndian() =>
            BinaryPrimitives.ReadSingleBigEndian(ReadExactBytes(reader, sizeof(float)));

PowerKit/Extensions/BinaryReaderExtensions.cs:166

• Same concern as ReadSingleEndian: BinaryPrimitives.ReadDoubleEndian isn’t uniformly available across all TFMs this library targets per the PR description. A BitConverter-based implementation avoids conditional compilation and keeps behavior consistent.

        /// <summary>
        /// Reads an 8-byte floating-point value from the stream using big-endian byte order.
        /// </summary>
        public double ReadDoubleBigEndian() =>
            BinaryPrimitives.ReadDoubleBigEndian(ReadExactBytes(reader, sizeof(double)));

PowerKit/Extensions/BinaryWriterExtensions.cs:165

• These float write helpers call BinaryPrimitives.WriteSingle*Endian, but the PR description indicates those overloads aren’t available on all target frameworks (netstandard2.0/net462 with System.Memory 4.6.3). Using BitConverter + conditional Array.Reverse avoids potential multi-target build failures and keeps the API available everywhere.

        /// <summary>
        /// Writes a 4-byte floating-point value to the stream using big-endian byte order.
        /// </summary>
        public void WriteSingleBigEndian(float value)
        {

PowerKit/Extensions/BinaryWriterExtensions.cs:185

• Same concern as WriteSingleEndian: BinaryPrimitives.WriteDoubleEndian may not exist for all targeted TFMs per the PR description. BitConverter-based conversion keeps these methods available across targets.

        /// <summary>
        /// Writes an 8-byte floating-point value to the stream using big-endian byte order.
        /// </summary>
        public void WriteDoubleBigEndian(double value)
        {

[Tyrrrz]

@copilot since BinaryWriter's intrinsic methods are all just Write(...) overloads, we should do the same for our extensions: WriteBigEndian()/WriteLittleEndian()

[Copilot]

@copilot since BinaryWriter's intrinsic methods are all just Write(...) overloads, we should do the same for our extensions: WriteBigEndian()/WriteLittleEndian()

Done — renamed all Write*BigEndian/Write*LittleEndian methods to WriteBigEndian/WriteLittleEndian overloads, matching the Write(...) pattern of BinaryWriter's intrinsic methods. Tests updated accordingly.

[Tyrrrz]

@copilot order the methods you added by name and make the tests match that order

[Copilot]

@copilot order the methods you added by name and make the tests match that order

Done — all WriteBigEndian overloads are now grouped together first, followed by all WriteLittleEndian overloads. Tests are reordered to match.