Fix ReadOnlySpanGetReferenceAndReadInteger on BigEndian #2

[EgorBo]

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Issue Details

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Author:	EgorBo
Assignees:	EgorBo
Labels:	area-System.Memory
Milestone:	-

[EgorBo]

/azp run runtime-community

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Azure Pipelines successfully started running 1 pipeline(s).

[EgorBo]

@stephentoub @akoeplinger PTAL, I was too overconfident in my Big Endian skills in #85969 (comment)

runtime-community (Build linux-s390x Release AllSubsets_Mono) is green in this PR

[stephentoub]

I'm not clear on why this is the right answer. Can you explain?

[EgorBo]

My understanding is this:

// "hello world 2"
// LE: 68_00_65_00_6C_00_6C_00_6F_00_20_00_77_00_6F_00_72_00_6C_00_64_00_20_00_32_00
//        6F_00_6C_00_6C_00_65_00 (we read 8 bytes with offset = 1 bytes)
// 
//
// BE: 00_68_00_65_00_6C_00_6C_00_6F_00_20_00_77_00_6F_00_72_00_6C_00_64_00_20_00_32
//        68_00_65_00_6C_00_6C_00 (we read 8 bytes with offset = 1 bytes)
//

Console.WriteLine(
    BitConverter.ToString(
        Encoding.Unicode.GetBytes("hello world 2")).Replace("-", "_"));

[EgorBo]

Same picture for the int case (that worked):

// "hello world 1"
// LE: 68_00_65_00_6C_00_6C_00_6F_00_20_00_77_00_6F_00_72_00_6C_00_64_00_20_00_31_00
//     00_65_00_68 (read 4 bytes)
// 
//
// BE: 00_68_00_65_00_6C_00_6C_00_6F_00_20_00_77_00_6F_00_72_00_6C_00_64_00_20_00_31
//     00_68_00_65 (read 4 bytes)

so chars here have swapped order ('h' is 68_00 on LE and 00_68 on BE)

[stephentoub]

I see. Thanks.

[EgorBo]

@stephentoub can you approve then? 🙂

[stephentoub]

GitHub wasn't letting me. Now it is. Done.