in reply to Re: pack auto-chomps/chops?
in thread pack auto-chomps/chops?

Ah, that's tricky. I suppose you're right, though. Do you know if there's a web-browsable version of the Perl source code anywhere I could check into that?

By the way, your solution works but is slower than just appending a "\n" to the end during the final map.

print pack("A25",pack("V*",map{1919242272+$_}(34481450,-49737472,6228,0,-285028276,6979,-1380265972)))

Replies are listed 'Best First'.
Re^3: pack auto-chomps/chops?
by ikegami (Patriarch) on Oct 07, 2009 at 19:18 UTC

    your solution works but is slower than just appending a "\n" to the end during the final map

    If pack is faster — seems odd — you could use Z instead of A.

    Ah, that's tricky. I suppose you're right, though. Do you know if there's a web-browsable version of the Perl source code anywhere I could check into that?

    http://perl5.git.perl.org/perl.git Look for pp_unpack in pp*.c (probably pp.c specifically pp_pack.c).

    The relevant code: 

    1458                     for (ptr = s+len-1; ptr >= s; ptr--)
1459                         if (*ptr != 0 && !isSPACE(*ptr)) break;
1460                     ptr++;

    [download]

    and 

    #define isSPACE(c) \
        ((c) == ' ' || (c) == '\t' || (c) == '\n' || (c) =='\r' || (c)
+ == '\f')

    [download]
    aka \s

    Update: Added relevant code.

[reply]
[d/l]
[select]

      Thanks, that really helps clear it up. As far as speed goes, I increased my data set and the 3 solutions (pack-and-append, pack-with-Z, and substr) are very tightly tied. I'll go with the Z approach for my final code.

      print pack("A25",pack("V*",map{1919242272+$_}(34481450,-49737472,6228,0,-285028276,6979,-1380265972)))
[reply]
[d/l]

In Section Seekers of Perl Wisdom