#!/usr/bin/env perl

use 5.014;
use warnings;
use Time::HiRes qw/time/;
use Benchmark qw/cmpthese timethese/;
use Inline 'C';

sub hash_pack($)   { join '', sort unpack '(A10)*', shift }
sub hash_re($)     { join '', sort $_[0] =~ /(\d{10})/g   }
sub hash_substr($) {
    my @nums; my $s = shift;
    while ($s) {
        push @nums, substr($s,0,10);
        $s = substr($s,10);
    }
    join '',sort @nums;
}
# Only considers first 3 numbers
sub hash_substr2($) {
    join '', sort substr($_[0],0,10),substr($_[0],10,10),substr($_[0],20,10);
}

my @funcs = map { "hash_$_" } qw/pack re substr substr2 c/;

my @strings = qw/512567000151256700025125670003
                 512567000251256700015125670003
                 512567000351256700015125670002/;

for my $s (@strings) {
    printf "%12s(%s) => %s\n", $_, $s, eval "$_(\$s)" for @funcs;
}

my $s = $strings[0];
cmpthese timethese(-5, { map { $_ => "$_('$s')" } @funcs });

__END__
__C__

/* Try our own splitter sort. This swaps the numbers in-place
 * as necessary to obtain a sorted order. */
#include <string.h>
#define SIZE    10
#define strswap(s1,s2,size) {           \
    int i;                              \
    for (i = 0; i < size; i++) {        \
        s1[i] = s1[i] ^ s2[i];          \
        s2[i] = s1[i] ^ s2[i];          \
        s1[i] = s1[i] ^ s2[i];          \
    }                                   \
}

char * hash_c(char *str) {
    char *n0 = str;
    char *n1 = str + SIZE;
    char *n2 = str + SIZE + SIZE;

    if (strncmp(n0, n1, SIZE) > 0)
        strswap(n0, n1, SIZE);

    if (strncmp(n1, n2, SIZE) > 0)
        strswap(n1, n2, SIZE);

    if (strncmp(n0, n1, SIZE) > 0)
        strswap(n0, n1, SIZE);

    return str;
}

##</code><code>##

   hash_pack(512567000151256700025125670003) => 512567000151256700025125670003
     hash_re(512567000151256700025125670003) => 512567000151256700025125670003
 hash_substr(512567000151256700025125670003) => 512567000151256700025125670003
hash_substr2(512567000151256700025125670003) => 512567000151256700025125670003
      hash_c(512567000151256700025125670003) => 512567000151256700025125670003
   hash_pack(512567000251256700015125670003) => 512567000151256700025125670003
     hash_re(512567000251256700015125670003) => 512567000151256700025125670003
 hash_substr(512567000251256700015125670003) => 512567000151256700025125670003
hash_substr2(512567000251256700015125670003) => 512567000151256700025125670003
      hash_c(512567000151256700025125670003) => 512567000151256700025125670003
   hash_pack(512567000351256700015125670002) => 512567000151256700025125670003
     hash_re(512567000351256700015125670002) => 512567000151256700025125670003
 hash_substr(512567000351256700015125670002) => 512567000151256700025125670003
hash_substr2(512567000351256700015125670002) => 512567000151256700025125670003
      hash_c(512567000151256700025125670003) => 512567000151256700025125670003
Benchmark: running hash_c, hash_pack, hash_re, hash_substr, hash_substr2 for at least 5 CPU seconds...
    hash_c:  6 wallclock secs ( 5.71 usr +  0.00 sys =  5.71 CPU) @ 4606276.36/s (n=26301838)
 hash_pack:  6 wallclock secs ( 5.07 usr +  0.00 sys =  5.07 CPU) @ 646938.07/s (n=3279976)
   hash_re:  6 wallclock secs ( 5.03 usr +  0.00 sys =  5.03 CPU) @ 422000.20/s (n=2122661)
hash_substr:  5 wallclock secs ( 5.04 usr +  0.00 sys =  5.04 CPU) @ 328204.96/s (n=1654153)
hash_substr2:  4 wallclock secs ( 5.14 usr +  0.00 sys =  5.14 CPU) @ 965458.95/s (n=4962459)
                  Rate hash_substr    hash_re  hash_pack hash_substr2     hash_c
hash_substr   328205/s          --       -22%       -49%         -66%       -93%
hash_re       422000/s         29%         --       -35%         -56%       -91%
hash_pack     646938/s         97%        53%         --         -33%       -86%
hash_substr2  965459/s        194%       129%        49%           --       -79%
hash_c       4606276/s       1303%       992%       612%         377%         --