After downloading and building Parrot to experiment with this weekend, I decided to set about writing something with the Parrot assembler. The result, a new signature for myself, written to run in Parrot - This signature is based upon my existing signature, which converts a 32 bit binary number, representing the post number, into a decimal number.

However, given the lower level of operations within the Parrot engine, a different algorithm to solve this problem was employed, than that used in my signature previously. The equivalent perl code for the algorithm employed follows the Parrot code.


        set     S0, "00000000000000000000001001000010"
        length  I0, S0
        set     I1, 1
        set     I2, 0
LOOP:   dec     I0
        substr  S1, S0, I0, 1
        if      S1, INC
RETURN: mul     I1, I1, 2
        ge      I0, 0, LOOP
        print   I2
        print   "\n"
        end
INC:    add     I2, I1
        branch  RETURN

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And then compiling the Parrot assembler to bytecode and executing this:


rob@kathmandu:~/parrot-0.0.10$ perl assemble.pl count.pasm >count.pbc
rob@kathmandu:~/parrot-0.0.10$ ./parrot count.pbc
578
rob@kathmandu:~/parrot-0.0.10$

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For those unfamiliar with Parrot assembly, the Parrot code above is roughly equivalent to the following Perl code:


$s0 = "00000000000000000000001001000010";
$i0 = length $s0;
$i1 = 1;
$i2 = 0;
while ( $i0 >= 0 )
{
    --$i0;
    $s1 = substr( $s0, $i0, 1 );
    if ( $s1 eq '1' )
    {
        $i2 += $i1;
    }
    $i1 *= 2;
};
print $i2, "\n";

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From my foray into Parrot assembler this weekend, I must say that I am quite impressed with its development and documentation to date. For those interesting in following my lead and investigating Parrot, I would recommend the following pages and resources:

 

rob@kathmandu:~/parrot-0.0.10$ perl assemble.pl count.pasm >count.pbc ; ./parrot count.pbc

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