cheers brothers and sisters,

I have this sub to calculate the 3 most significant bits based on an integer. The integer I get is the integer value of the TOS byte, a value which is retreived over SNMP. I have to find the TOS Precedence, and that is the sum of the 3 MSBs.

The sub I have works, but laziness seems to strike everyone eventually, I was wondering if there are easier or better ways to do it? I'm just always curious about how someone else would do it ;-)

the code: 
sub calc_tosprecedence {
    my $int_val  = shift;
    my $bit = 7;
    my @b = (0,0,0,0,0,0,0,0);
    while ($int_val > 0 ) {
        $rest = 1 if $int_val - 2**$bit >= 0 ;
        $rest = 0 if $int_val - 2**$bit < 0 ;
        $int_val = $int_val - 2**$bit if $rest;
        $b[$bit-- ] = $rest;
    }
    @b = reverse @b;
    my @prec = @b[0 .. 2];
    $sum = 0;
    @prec = reverse @prec;
    $sum += $prec[$_] * 2**$_ for (0 .. $#prec);
    return $sum
}

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The code basically:
  • gets an integer as argument
  • converts it to a binary
  • takes the 3 last (MSB) bits from it as a binary
  • calculates the integer value of that binary

    • Thanks..

    --
    to ask a question is a moment of shame
    to remain ignorant is a lifelong shame

    In reply to calculating the 3 MSBs from an integer by insaniac

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