Calculating Most and Least Significant Byte

Numbers are stored internally as bytes. An Int32 value, for example, uses four bytes. Sometimes it is required to split up the number into its byte parts, for example, to calculate checksums with the least significant byte.

Guide to Handling Numbers in Bytes

We have created a quick walk-through that you can also use as a basic number handling tutorial. It illustrates how numbers correspond to bits, how to split numbers to bytes, how to calculate least significant byte (LSB) and most significant byte (MSB), and more:

function Show-Header([Parameter(ValueFromRemainingArguments)][string]$Text)
{
  $Width=80
  $padLeft = [int]($width / 2) + ($text.Length / 2)
  ''
  $text.PadLeft($padLeft, "=").PadRight($Width, "=")
  ''
}


Show-Header Starting with this number:
$number = 26443007
$number

Show-Header Display the bits for this number:
$bits = [Convert]::ToString($number,2)
$bits 

Show-Header Add missing leading zeroes:
# pad the string to its full bit range (32 bits)
$bitsAligned = $bits.PadLeft(32, '0') 
$bitsAligned

Show-Header Display the four byte groups
$bitsAligned -split '(?<=\G.{8})(?=.)' -join '-'

Show-Header Get the bytes by conversion to IPAddress object:
$bytes = ([Net.IPAddress]$number).GetAddressBytes()
$bytes

Show-Header Display the bits for the IPAddress bytes:
$bitbytes = $bytes | ForEach-Object { [Convert]::ToString($_, 2).PadLeft(8,'0')}
$bitbytes -join '-'

Show-Header Show the Least Significant Byte LSB:
$bytes[0]

Show-Header Show LSB by turning the 8 bits to the right into a number to verify:
$bits = [Convert]::ToString($number, 2)
# take least significant bits
[Convert]::toByte($bits.Substring($bits.Length-8),2)

Show-Header Show the Most Significant Byte MSB:
$bytes[3]

As you can see, there are many ways to get there. One especially clever way is converting a number to an IPAddress. IPAddress objects have a handy GetAddressBytes() method that splits the number easily into its bytes for you.

The result looks like this:

 
===========================Starting with this number:===========================

26443007

=======================Display the bits for this number:========================

1100100110111110011111111

===========================Add missing leading Zeroes:==========================

00000001100100110111110011111111

==========================Display the four byte groups==========================

00000001-10010011-01111100-11111111

================Get the bytes by conversion to IPAddress object:================

255
124
147
1

===================Display the bits for the IPAddress bytes:====================

11111111-01111100-10010011-00000001

======================Show the Least Significant Byte LSB:======================

255

======Show LSB by turning the 8 bits to the right into a number to verify:======

255

=======================Show the Most Significant Byte MSB:======================

1

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