use warnings;
use Benchmark;

use Inline C => Config =>
  BUILD_NOISY => 1;

use Inline C => <<'EOC';

int uv_fits_double3(SV * x, ...) {
  dXSARGS;
  int i, count = 0;
  UV arg;

  for(i = 0; i < items; i++) {
    arg = SvUV(ST(i));
    if(arg) {
      while(!(arg & 1)) arg >>= 1;
      if(arg < 9007199254740993) count++;
    }
  }
  return count;
}

int uv_fits_double_bitfiddle(SV * t, ...) {
  dXSARGS;
  int i, count = 0;
  UV arg;

  for(i = 0; i < items; i++) {
    arg = SvUV(ST(i));
    IV smallest_invalid = (arg & -arg) << 53;
    UV valid_bits = smallest_invalid - 1;
    UV invalid_bits = ~valid_bits;
    if ( !(arg & invalid_bits)) count++;
  }
  return count;
}

int uv_fits_double3x(SV* the_min, SV* the_max) {
  dXSARGS;
  UV i_min = SvUV(the_min);
  UV i_max = SvUV(the_max);
  UV i;
  int count = 0;
  UV arg;

  for(i = i_min; i < i_max; i++) {
    arg = i;
    if(arg) {
      while(!(arg & 1)) arg >>= 1;
      if(arg < 9007199254740993) count++;
    }
  }
  return count;
}

int uv_fits_double_bitfiddle2(SV* the_min, SV* the_max) {
  dXSARGS;
  UV i_min = SvUV(the_min);
  UV i_max = SvUV(the_max);
  UV i;
  int count = 0;

  for(i = i_min; i < i_max; i++) {
      UV arg = i;
      IV neg = -arg;
      IV smallest_invalid = (arg & -arg)<<53;
      UV valid_bits = smallest_invalid-1;
      UV invalid_bits = ~valid_bits;
      if (! (arg & invalid_bits)) count++;
  }
  return count;
}

int uv_empty_func(SV* the_min, SV* the_max) {
    dXSARGS;
    UV i_min = SvUV(the_min);
    UV i_max = SvUV(the_max);
    return i_max - i_min;
}

int uv_empty_loop(SV* the_min, SV* the_max) {
    dXSARGS;
    UV i_min = SvUV(the_min);
    UV i_max = SvUV(the_max);
    UV i;
    int count = 0;
    for(i = i_min; i < i_max; i++) {
        UV arg = i;
        // boring
        count++;
    }
    return count * i_max - i_min;
}

EOC

@in2 = (
    [ 1844674407366955161, 1844674407378955161 ],
    [    9007199248740992,    9007199260740992 ],
    [     184467436737095,     184467448737095 ],
    [        184463440737,        184475440737 ],
);

push @in, $_->[0] .. $_->[1] for @in2;

print "=== Test 1: roughly equivalent speed\n";
our ($count1, $count2);

($count1, $count2) = (0, 0);

timethese (5, {
    'uv_fits_double3'    =>       '$count1 = uv_fits_double3(@in);',
    'uv_fits_double_bitfiddle' => '$count2 = uv_fits_double_bitfiddle(@in);',
});
print "$count1 $count2 (", scalar(@in), ")\n";
print "!!!! MISMATCH !!!!\n"
  if $count1 != $count2;


print "\n=== TEST 2: twiddle has an advantage if we don't use SvUV()\n";

($count1, $count2, $count3) = (0, 0, 0, 0);

timethese (10000, {
    'double3x' => '$count1 = uv_fits_double3x(@{$in2[0]})'
                 .'        + uv_fits_double3x(@{$in2[1]})'
                 .'        + uv_fits_double3x(@{$in2[2]})'
                 .'        + uv_fits_double3x(@{$in2[3]})'
                 ,
    'bitfiddle_3x'=>'$count2 = uv_fits_double_bitfiddle2(@{$in2[0]})'
                   .'        + uv_fits_double_bitfiddle2(@{$in2[1]})'
                   .'        + uv_fits_double_bitfiddle2(@{$in2[2]})'
                   .'        + uv_fits_double_bitfiddle2(@{$in2[3]})'
                   ,
    'empty_func'=>'$count3 = uv_empty_func(@{$in2[0]})'
                 .'       + uv_empty_func(@{$in2[1]})'
                 .'       + uv_empty_func(@{$in2[2]})'
                 .'       + uv_empty_func(@{$in2[3]})'
                 ,
    'empty_loop'=>'$count4 = uv_empty_loop(@{$in2[0]})'
                 .'       + uv_empty_loop(@{$in2[1]})'
                 .'       + uv_empty_loop(@{$in2[2]})'
                 .'       + uv_empty_loop(@{$in2[3]})'
                 ,
});
print "$count1 $count2 $count3 $count4\n";
print "!!!! MISMATCH !!!!\n" if $count1 != $count2;