Hmm, thanks for that. I am using the tests out of the C module and unfortunately they got the order wrong so you need to reverse got/expected. Before the patch it was failing like this:

t/1......# Test 3 got: "0.814723691903055" (t/1.t at line 13)
#   Expected: "873847195.017769552"
#  t/1.t line 13 is: ok(0.814723691903055, $gen->rand());
# Test 4 got: "0.135477004107088" (t/1.t at line 14)
#   Expected: "2307073947.03889426"
[snip]
[download]

In the first test it expects 0.814xxxxx and was getting a large float becuase the final stage on output is to multiply the "uint32" by (1.0/4294967296.0). If the uint32 is actually a uint64 you get a big float. Obviously the patch is now appropriately constraining the int to 32 bits but there is still an issue.

I would not ask you to debug it but if you were going to look the algorithm consists of a setup phase mt_init_seed() and an extraction phase mt_genrand(). Only failures in 5.t relate to mt_setup_array() so that code is not relevant.

Adding a debugging printf to the C here:

void mt_init_seed( struct mt *m, uint32_t seed )
{
    int i;
    uint32_t *mt;

    mt = m->mt;
    mt[0] = seed & 0xffffffff;
    for ( i = 1; i < N; i++ ) {
        mt[i] = 1812433253 * (mt[i-1]^(mt[i-1]>>30)) + i;
        printf("init %d: %u\n", i, mt[i]);  // what we want
    }
    m->mti = N;
}

and running

$ perl -MMath::Random::MT -e "Math::Random::MT->new(1)" > out
[download]

Gives the setup for a seed of value 1 (included after readmore) If you add that line to the equivilent place in the Perl version (around line 48):

sub mt_init_seed {
    my ($self, $seed) = @_;
    my @mt;
    $mt[0] = $seed & 0xffffffff;
    for ( my $i = 1; $i < $N; $i++ ) {
        my $xor = $mt[$i-1]^($mt[$i-1]>>30);
        { use integer;  $mt[$i] = 1812433253 * $xor + $i; $mt[$i] >>= 
+32 if $mt[$i] > 0xffffffff }
        printf("init %d: %u\n", $i, $mt[$i]);
    }
    $self->{mt} = \@mt;
    $self->{mti} = $N;
}

and running

perl -MMath::Random::MT::Perl -e "Math::Random::MT::Perl->new(1)" > ou
+tp
[download]

Would let me see if the setup is working as expected. Here is the expected output for a seed value 1 from the C.

perl -MMath::Random::MT::Perl -e "Math::Random::MT::Perl->new(1)" > ou
+tp
[download]

Would let me see if the setup is working as expected...

I get a more 'sawtooth'-like pattern like this:

init 1: 1812433254
init 2: 764828710
init 3: 322750068
init 4: 136197301
init 5: 57473899
init 6: 24253410
init 7: 10234696
init 8: 4318939
init 9: 1822549
init 10: 769097
init 11: 324551
init 12: 136957
init 13: 57794
init 14: 24388
init 15: 10291
init 16: 4342
init 17: 1832
init 18: 773
init 19: 326
init 20: 137
init 21: 57
init 22: 24
init 23: 10
init 24: 4
init 25: 1
init 26: 1812433279
init 27: 764828720
init 28: 322750072
init 29: 136197303
init 30: 57473900
init 31: 24253411
init 32: 10234696
init 33: 4318939
init 34: 1822549
init 35: 769097
init 36: 324551
init 37: 136957
init 38: 57794
init 39: 24388
init 40: 10291
init 41: 4342
init 42: 1832
init 43: 773
init 44: 326
init 45: 137
init 46: 57
init 47: 24
init 48: 10
init 49: 4
init 50: 1
...
[download]

(of course, I could also send you the whole output if it helps...)

BTW, here's the respective line from the perl -V output

    use64bitint=define use64bitall=define uselongdouble=undef
[download]

which looks to me like 64-bit ints have in fact been configured...