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in reply to emulate 32-bit on perl 64

My recommendation is to use 32-bit bitwise operations instead of using unrestricted bitwise operations, or to operate on 64 bits worth of data instead of 32 bits at a time.

As you don't show any code, it is hard to give any more concrete advice. Please post a Short, Self Contained, Correct (Compilable), Example so we can see what the cause for your problem might be and suggest appropriate remedies or workarounds.

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Re^2: emulate 32-bit on perl 64
by loofort (Initiate) on Jan 11, 2012 at 15:17 UTC
    I'm not sure that example brings any clearence. I'm not the author and I use it as black box. here is little part:: 
    for ($h = 16; $h < 80; $h++) {
    $i[$h] = a2 ($i[$h - 3] ^ $i[$h - 8] ^ $i[$h - 14] ^ $i[$h - 16], 
+1);
}

sub a2 {
    my ($b, $a) = @_;
    
    my $c = $b >> 32 - $a;
    my $e = (1 << 32 - $a) - 1;
    my $d = $b & $e;
    
    return tos($d << $a | $c);
}

sub tos {
    my ($num) = @_;
    $num = $num - 4294967296 if $num > 4294967295;
    $num = $num + 4294967296 if $num < -2147483648;
            
    if ($num >= 0) {
        $num = $num - 2 ** 32 if ($num >> 31);
    }
    return $num;
}

    [download]
[reply]
[d/l]

      There is no magic to sprinkle over an algorithm that relies on 32-bit integers to make it behave with other integer sizes. The hardcoded numbers here are magic for 32-bit numbers:

          $num = $num - 4294967296 if $num > 4294967295;
    $num = $num + 4294967296 if $num < -2147483648;

      [download]

      You will have to understand the algorithm involved to be able to make the required changes. Alternatively, you can run the program under a Perl compiled with 32-bit integers.

[reply]
[d/l]

      Try this -- 'scuse the formatting, but there's no good way to format it. It produces the same results on 32-bit and 64-bit Perls for one randomly generated set of input data: 

      for( my $h = 16; $h < 80; $h++ ) {
    $i[$h] = a2(
        (
            (
                (
                    (
                        ( $i[$h - 3] ^ $i[$h - 8] ) & 0xffffffff
                    ) ^ $i[$h - 14]
                ) & 0xffffffff
            ) ^ $i[$h - 16]
        ) & 0xffffffff
    , 1
    );
}

print "@i";

sub a2 {
    my ($b, $a) = @_;

    my $c = $b >> 32 - $a;
    my $e = (1 << 32 - $a) - 1;
    my $d = $b & $e;

    return tos($d << $a | $c);
}

sub tos {
    my ($num) = @_;
    $num = $num - 4294967296 if $num > 4294967295;
    $num = $num + 4294967296 if $num < -2147483648;

    if ($num >= 0) {
        $num = $num - 2 ** 32 if ($num >> 31);
    }
    return $num;
}

      [download]
      With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.

      The start of some sanity?
[reply]
[d/l]

      This is slightly more readable:

      sub fix32{ $_[0] & 0xffffffff }

for( my $h = 16; $h < 80; $h++ ) {
    $i[$h] = a2(
        fix32( fix32( fix32( $i[$h - 3] ^ $i[$h - 8] ) ^ $i[$h - 14] )
+ ^ $i[$h - 16] )
        , 1
    );
}

      [download]
      With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.

      The start of some sanity?
[reply]
[d/l]

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