IntVal(float) Returns Different Values (Porting Delphi code to mix a block of data)

[Bruce <bvanderw@xxxxxxxxx>]

I am having trouble porting some code originally written in Borland Delphi
to PHP. The Delphi code expects certain behavior on integer overflows that I
can only duplicate on some PHP systems. For example:

$BB = -2181087916;
$AA = (int)$BB;
$AA = intval($BB);

On some systems, $AA will be (int)-2147483648, however, on most systems, $AA
will be (int)2113879380, which is the same value truncated at 32 bits. It is
this latter behavior that I need to properly port the Delphi code.

Can someone suggest a way to do this that is consistent on all platforms?
For reference, I am attaching the Delphi code and my PHP port.

Thanks...

--Bruce

{quick (block) mixer routine}
procedure MixBlock(const Matrix : T128bit; var Block; Encrypt : Boolean);

const
  CKeyBox : array [False..True, 0..3, 0..2] of LongInt =

    (((0, 3, 1), (2, 1, 3), (1, 0, 2), (3, 2, 0)),
    ((3, 2, 0), (1, 0, 2), (2, 1, 3), (0, 3, 1)));

var
  Blocks : array [0..1] of LongInt absolute Block;
  Work : LongInt;
  Right : LongInt;
  Left : LongInt;

  R : LongInt;
  AA, BB : LongInt;
  CC, DD : LongInt;

begin
  Right := Blocks[0];
  Left := Blocks[1];

  for R := 0 to 3 do begin
  {transform the right side}
    AA := Right;
    BB := Matrix[CKeyBox[Encrypt, R, 0]];

    CC := Matrix[CKeyBox[Encrypt, R, 1]];
    DD := Matrix[CKeyBox[Encrypt, R, 2]];

    AA := AA + DD; DD := DD + AA; AA := AA xor (AA shr 7);
    BB := BB + AA; AA := AA + BB; BB := BB xor (BB shl 13);

    CC := CC + BB; BB := BB + CC; CC := CC xor (CC shr 17);
    DD := DD + CC; CC := CC + DD; DD := DD xor (DD shl 9);

    AA := AA + DD; DD := DD + AA; AA := AA xor (AA shr 3);
    BB := BB + AA; BB := BB xor (BB shl 7);

    CC := CC + BB;
    CC := CC xor (DD shr 15);
    DD := DD + CC;
    DD := DD xor (DD shl 11);

    Work := Left xor DD;
    Left := Right;
    Right := Work;
  end;

  Blocks[0] := Left;

  Blocks[1] := Right;
end;

Here is my PHP port:

 <?php
function zeroFill($a, $b)
{
  $z = hexdec(80000000);
  if ($z & $a)
  {
    $a >>= 1;
    $a &= (~ $z);
    $a |= 0x40000000;
    $a >>= ($b-1);
  }
  else
  {
    $a >>= $b;
  }
  return $a;
}

function MixBlock($AKey, &$ACode, $Encrypt)
{
  $CKeyBox = array(array(3, 2, 0), array(1, 0, 2), array( 2, 1, 3), array(0 ,
3, 1));

  $Right = $ACode[0];
  $Left = $ACode[1];

  for ($R=0; $R<= 3; $R++)
  {
    $AA = $Right;
    if ($Encrypt)
    {
      $BB = $AKey[$CKeyBox[ $R][0]];
      $CC = $AKey[$CKeyBox[ $R][1]];
      $DD = $AKey[$CKeyBox[ $R][2]];
    }
    else
    {
      $BB = $AKey[$CKeyBox[ 3-$R][0]];
      $CC = $AKey[$CKeyBox[ 3-$R][1]];
      $DD = $AKey[$CKeyBox[ 3-$R][2]];
    }

    $AA = (int)$AA + (int)$DD;
    $DD = (int)$DD + (int)$AA;
    $AA = (int)$AA ^ zeroFill( $AA, 7);
    $BB = (int)$BB + (int)$AA;
    $AA = (int)$AA + (int)$BB;

    $BB = (int)$BB ^ ((int)$BB << 13);
    $CC = (int)$CC + (int)$BB; $BB = (int)$BB + (int)$CC;
    $CC = (int)$CC ^ zeroFill( $CC, 17);
    $DD = (int)$DD + (int)$CC; $CC = (int)$CC + (int)$DD;
    $DD = (int)$DD ^ ((int)$DD << 9);

    $AA = (int)$AA + (int)$DD; $DD = (int)$DD + (int)$AA;
    $AA = (int)$AA ^ zeroFill( $AA, 3);
    $BB = (int)$BB + (int)$AA;
    $BB = (int)$BB ^ (int)((int)$BB << 7);
    $CC = (int)$CC + (int)$BB;
    $CC = (int)$CC ^ zeroFill( $DD, 15);
    $DD = (int)$DD + (int)$CC;
    $DD = (int)$DD ^ (int)((int)$DD << 11);

    $Work = $Left ^ $DD;
    $Left = $Right;
    $Right = $Work;
  }

  $ACode[0] = $Left;
  $ACode[1] = $Right;
}
?>