after-after.pm6

# always fails first time after `rm -rf lib/.precomp` with a segfault
# but always passes all subsequent runs

# removed --> Seq and return an array

multi sub decode-base64(Str $str, :$pad, :@alpha, |c) {
    my $encodings = chars64with(@alpha);
    my @values = $str.comb(/@$encodings/).rotor(4, :partial).map: -> $chunk {
        state %lookup = $encodings.kv.hash.antipairs;
        my $n   = [+] $chunk.map: { (%lookup{$_} || 0) +< ((state $m = 24) -= 6) }
        my $res = (16, 8, 0).map: { $n +> $_ +& 255 }
        #slip($res.grep(* > 0));
        slip($res.head( 3 - ( 4 - $chunk.elems ) ) );
    }
    return @values;
}

after.pm6

# gives correct results, but segfaults randomly (also Internal error: invalid thread ID 65 in GC work pass)

multi sub decode-base64(Str $str, :$pad, :@alpha, |c --> Seq) {
    my $encodings = chars64with(@alpha);
    my @result = $str.comb(/@$encodings/).rotor(4, :partial).map: -> $chunk {
        state %lookup = $encodings.kv.hash.antipairs;
        my $n   = [+] $chunk.map: { (%lookup{$_} || 0) +< ((state $m = 24) -= 6) }
        my $res = (16, 8, 0).map: { $n +> $_ +& 255 }
        #slip($res.grep(* > 0));
        slip($res.head( 3 - ( 4 - $chunk.elems ) ) );
    }
    @result.Seq;
}

before.pm6

# always fails, losing items at index 1 and 2

multi sub decode-base64(Str $str, :$pad, :@alpha, |c --> Seq) {
    my $encodings = chars64with(@alpha);
    $str.comb(/@$encodings/).rotor(4, :partial).map: -> $chunk {
        state %lookup = $encodings.kv.hash.antipairs;
        my $n   = [+] $chunk.map: { (%lookup{$_} || 0) +< ((state $m = 24) -= 6) }
        my $res = (16, 8, 0).map: { $n +> $_ +& 255 }
        #slip($res.grep(* > 0));
        slip($res.head( 3 - ( 4 - $chunk.elems ) ) );
    }
}