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Date: Sun, 19 Mar 2006 19:53:30 -0500
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Subject: IntVal(float) Returns Different Values
From: bvanderw@gmail.com (Bruce)

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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 =3D -2181087916;
$AA =3D (int)$BB;
$AA =3D intval($BB);

On some systems, $AA will be int(-2147483648), however, on most systems, $A=
A
will be int(2113879380), which is the same value truncated at 32 bits. It i=
s
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 =3D
    (((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 :=3D Blocks[0];
  Left :=3D Blocks[1];

  for R :=3D 0 to 3 do begin
  {transform the right side}
    AA :=3D Right;
    BB :=3D Matrix[CKeyBox[Encrypt, R, 0]];
    CC :=3D Matrix[CKeyBox[Encrypt, R, 1]];
    DD :=3D Matrix[CKeyBox[Encrypt, R, 2]];

    AA :=3D AA + DD; DD :=3D DD + AA; AA :=3D AA xor (AA shr 7);
    BB :=3D BB + AA; AA :=3D AA + BB; BB :=3D BB xor (BB shl 13);
    CC :=3D CC + BB; BB :=3D BB + CC; CC :=3D CC xor (CC shr 17);
    DD :=3D DD + CC; CC :=3D CC + DD; DD :=3D DD xor (DD shl 9);

    AA :=3D AA + DD; DD :=3D DD + AA; AA :=3D AA xor (AA shr 3);
    BB :=3D BB + AA; BB :=3D BB xor (BB shl 7);
    CC :=3D CC + BB;
    CC :=3D CC xor (DD shr 15);
    DD :=3D DD + CC;
    DD :=3D DD xor (DD shl 11);

    Work :=3D Left xor DD;
    Left :=3D Right;
    Right :=3D Work;
  end;

  Blocks[0] :=3D Left;
  Blocks[1] :=3D Right;
end;

Here is my PHP port:

 <?php
function zeroFill($a, $b)
{
  $z =3D hexdec(80000000);
  if ($z & $a)
  {
    $a >>=3D 1;
    $a &=3D (~ $z);
    $a |=3D 0x40000000;
    $a >>=3D ($b-1);
  }
  else
  {
    $a >>=3D $b;
  }
  return $a;
}

function MixBlock($AKey, &$ACode, $Encrypt)
{
  $CKeyBox =3D array(array(3, 2, 0), array(1, 0, 2), array(2, 1, 3), array(=
0,
3, 1));

  $Right =3D $ACode[0];
  $Left =3D $ACode[1];

  for ($R=3D0; $R<=3D3; $R++)
  {
    $AA =3D $Right;
    if ($Encrypt)
    {
      $BB =3D $AKey[$CKeyBox[$R][0]];
      $CC =3D $AKey[$CKeyBox[$R][1]];
      $DD =3D $AKey[$CKeyBox[$R][2]];
    }
    else
    {
      $BB =3D $AKey[$CKeyBox[3-$R][0]];
      $CC =3D $AKey[$CKeyBox[3-$R][1]];
      $DD =3D $AKey[$CKeyBox[3-$R][2]];
    }

    $AA =3D (int)$AA + (int)$DD;
    $DD =3D (int)$DD + (int)$AA;
    $AA =3D (int)$AA ^ zeroFill($AA, 7);
    $BB =3D (int)$BB + (int)$AA;
    $AA =3D (int)$AA + (int)$BB;

    $BB =3D (int)$BB ^ ((int)$BB << 13);
    $CC =3D (int)$CC + (int)$BB; $BB =3D (int)$BB + (int)$CC;
    $CC =3D (int)$CC ^ zeroFill($CC, 17);
    $DD =3D (int)$DD + (int)$CC; $CC =3D (int)$CC + (int)$DD;
    $DD =3D (int)$DD ^ ((int)$DD << 9);

    $AA =3D (int)$AA + (int)$DD; $DD =3D (int)$DD + (int)$AA;
    $AA =3D (int)$AA ^ zeroFill($AA, 3);
    $BB =3D (int)$BB + (int)$AA;
    $BB =3D (int)$BB ^ (int)((int)$BB << 7);
    $CC =3D (int)$CC + (int)$BB;
    $CC =3D (int)$CC ^ zeroFill($DD, 15);
    $DD =3D (int)$DD + (int)$CC;
    $DD =3D (int)$DD ^ (int)((int)$DD << 11);

    $Work =3D $Left ^ $DD;
    $Left =3D $Right;
    $Right =3D $Work;
  }

  $ACode[0] =3D $Left;
  $ACode[1] =3D $Right;
}
?>

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