JsonWriterHelper.Transcoding.cs replacement

[kasperk81]

old discussion: dotnet/corefx#34425 (comment)

runtime/src/libraries/System.Text.Json/src/System/Text/Json/Writer/JsonWriterHelper.Transcoding.cs

Line 28 in eeef4b1

public static unsafe OperationStatus ToUtf8(ReadOnlySpan<byte> utf16Source, Span<byte> utf8Destination, out int bytesConsumed, out int bytesWritten)

the corelib implementation this ToUtf8 method was shadowing back in 2018-2019 is accelerated with hardware intrinsics since and code was heavily refactored, but JsonWriterHelper.Transcoding is stuck in time. should it be replaced by corelib version?

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Issue Details

---

old discussion: dotnet/corefx#34425 (comment)

runtime/src/libraries/System.Text.Json/src/System/Text/Json/Writer/JsonWriterHelper.Transcoding.cs

Line 28 in eeef4b1

public static unsafe OperationStatus ToUtf8(ReadOnlySpan<byte> utf16Source, Span<byte> utf8Destination, out int bytesConsumed, out int bytesWritten)

the corelib implementation this ToUtf8 method was shadowing back in 2018-2019 is accelerated with hardware intrinsics since and code was heavily refactored, but JsonWriterHelper.Transcoding is stuck in time. should it be replaced by corelib version?

Author:	kasperk81
Assignees:	-
Labels:	area-System.Text.Json
Milestone:	-

[stephentoub]

should it be replaced by corelib version?

Yes. At least in builds where it can be.

[eiriktsarpalis]

@kasperk81 would you be interested in contributing a prototype targeting the shared framework routine?

[kasperk81]

@kasperk81 would you be interested in contributing a prototype targeting the shared framework routine?

https://github.com/dotnet/runtime/pull/75834/files has the prototype. some tests which are relying on impl details of JsonWriterHelper.Transcoding.cs are failing.. idk how realistic those tests are. feel free to use it.