CODEWITHSUNDEEP
powershellendianness
Ingmar
Ingmar

Reputation: 2648

Powershell: how to ensure endianess when storing int value

The task is how to store the bytes of an int value with the correct endianess.

Basically, this works fine when on x86 systems, and the value shall be little-endian, using the .NET function GetBytes():

[byte[]]$as_little_endian = [System.BitConverter]::GetBytes($value)

# e.g.:
$value = 0x12345678
[byte[]]$as_little_endian = [System.BitConverter]::GetBytes($value)
$as_little_endian | Format-Hex

# -> ...    78 56 34 12

For example, the result can now be appended to a file when $value is a checksum.

However, the result depends on the system architecture and may be different on other systems. There is no way to enforce a certain endianess, to keep the script independent.

As a workaround, I do this:

$as_little_endian = [System.BitConverter]::GetBytes($value)

if( -Not [System.BitConverter]::IsLittleEndian )
{
    [array]::Reverse($as_little_endian )
}

Is there a more elegant way to enforce endianess here?

Upvotes: 0

Views: 648

Answers (1)

js2010
js2010

Reputation: 27473

It looks like getbytes() returns the right order automatically. Note that tcp always uses bigendian. It seems unlikely that you would encounter a bigendian system.

The order of bytes in the array returned by the GetBytes method depends on whether the computer architecture is little-endian or big-endian.

BitConverter.GetBytes Method (System-int64) | Microsoft Learn

Upvotes: 0

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