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Date: Mon, 20 Mar 2006 20:22:21 +1200
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To: Bruce <bvanderw@gmail.com>
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References: <33a75ab80603191653tca7f454i8baa71015b5b0373@mail.gmail.com>
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Subject: Re: [PHP-DEV] IntVal(float) Returns Different Values
From: jasper@album.co.nz (Jasper Bryant-Greene)

You want the php-general mailing list. This list is for discussing 
development of the PHP language and runtime...

Jasper

Bruce wrote:
> 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;
> }
> ?>
>