DelphiBasics
Shr
Keyword
Shift an integer value right by a number of bits
  Number Shr bits
Description
The Shr keyword performs a bitwise shift right of an Integer. The number is shifted Bits to the right.
 
If Bits is greater than the size of the number type, the Bits value is Mod'ed by the number type size (minimum 32) before the shift.
Notes
Warning Only use Shr when a bit operation is required - do not use instead of a multiplication or division. First because it is unclear as to what is happening. Secondly, bits may be lost in the operation.

Warning The compiler will reject hardcoded shift right values that exceed 32, unless the data type is Int64. The same is not true for Shl.
Related commands
Hi Returns the hi-order byte of a (2 byte) Integer
Lo Returns the low-order byte of a (2 byte) Integer
Shl Shift an integer value left by a number of bits
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Example code : Shifting left and losing high bits before shifting right
var
  before, after : Word;
begin
  // Set up out starting number
  before := $3C;      // Hex 3C = 003C in the Word

  // Shift left by 12 will lose the top 12 bits of the Word
  after := before Shl 12;

  ShowMessageFmt('Before : %x',[before]);
  ShowMessageFmt('After shift left  : %x',[after]);

  // Shifting right by 12 will not recover the lost data
  after := after Shr 12;

  ShowMessageFmt('After shift right : %x',[after]);
end;
Show full unit code
   Before : 3C
   After shift left  : C000
   After shift right : C
 
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