Swapping order of bytes in Delphi

Question

I'm not very familiar with arrays of bite and big/little endians but I need to write an integer value into byte array in reverse and I don't know how to do it in Delphi code. C# has BitConverter.Reverse methong which is so much easier, is there any equivalent for it in Delphi? This is my code so far:

x := 1500977838953;
setLength(byteArray, 8);
Move(x, byteArray[2], SizeOf(x));
showMessage(ByteToHex(byteArray));

ByteToHex is a method that returns me hex string so I can read the bytes if they are in correct order. The result that I am getting is : 0000693B40795D01 but I need it to be: 00-00-01-5D-79-40-3B-69

Any ideas how I can achieve this?

Edit:

function ByteToHex(b: array of byte): String;
const HexSymbols = '0123456789ABCDEF';
var i: integer;
begin
  SetLength(Result, 2*Length(b));
  for i :=  0 to Length(b)-1 do begin
    Result[1 + 2*i + 0] := HexSymbols[1 + b[i] shr 4];
    Result[1 + 2*i + 1] := HexSymbols[1 + b[i] and $0F];
  end;
end;

Answer 1

Here is an example how to use the ReverseBytes() procedure:

program Project20;
{$APPTYPE CONSOLE}
uses
  System.SysUtils;

procedure ReverseBytes(Source, Dest: Pointer; Size: Integer);
begin
  Dest := PByte(NativeUInt(Dest) + Size - 1);
  while (Size > 0) do
  begin
    PByte(Dest)^ := PByte(Source)^;
    Inc(PByte(Source));
    Dec(PByte(Dest));
    Dec(Size);
  end;
end;

var x,y : Int64;

begin
  x := 1500977838953;
  WriteLn(x);
  ReverseBytes(Addr(x),Addr(y),SizeOf(x)); // Or ReverseBytes(@x,@y,SizeOf(x));
  WriteLn(IntToHex(x));
  WriteLn(IntToHex(y));
  ReadLn;
end.

Output:

1500977838953
0000015D79403B69
693B40795D010000

To get the address of a variable, use the Addr() function or the @ operator. The result is a 64-bit integer with all bytes in reversed order, as shown by the output.

There are other ways to swap the byte order of a variable. Search for bswap for example.