}
function bigint_powmod($x, $y, $m)
{
return gmp_powm($x, $y, $m);
}
} else {
if (extension_loaded('big_int')) {
function bigint_dec2num($dec)
/**
* Generates random number wich bit length $bits_cnt,
* using $random_generator as random generator function.
* If is_set_higher_bit != false, then higer bit of result
* will be set to 1.
*
* @param int $bits_cnt
* @param string $rnd_generator
* @return big_int resource
* @access public
*/
function getRand($bits_cnt, $random_generator, $is_set_higher_bit = false)
{
$tmp = bi_rand($bits_cnt, $random_generator);
return $is_set_higher_bit ? bi_set_bit($tmp, $bits_cnt - 1) : $tmp;
}
public static function random($n, $s)
{
switch (BigInt::support()) {
case 'gmp':
$result = gmp_init(0);
for ($i = 0; $i < $n; $i++) {
if (mt_rand(0, 1)) {
gmp_setbit($result, $i);
}
}
if ($s) {
gmp_setbit($result, $n - 1);
}
return $result;
case 'big_int':
$result = bi_rand($n);
if ($s) {
$result = bi_set_bit($result, $n - 1);
}
return $result;
case 'bcmath':
bcscale(0);
$t = BigInt::bcpow(2, $n);
if ($s == 1) {
$m = bcdiv($t, 2);
$t = bcsub($m, 1);
} else {
$m = 0;
$t = bcsub($t, 1);
}
$l = strlen($t);
$n = (int) ($l / 9) + 1;
$r = '';
while ($n) {
$r .= substr('000000000' . mt_rand(0, 999999999), -9);
--$n;
}
$r = substr($r, 0, $l);
while (bccomp($r, $t) == 1) {
$r = substr($r, 1, $l) . mt_rand(0, 9);
}
return bcadd($r, $m);
case '':
default:
return BigInt::_random($n, $s);
}
}
/*
bitset functions
*/
echo '<h3>bitset functions</h3>' . "\n";
echo '<div style="text-align:right">';
echo '$a = [', bi_to_str($a, 2), "]<br/>\n";
echo '$b = [', bi_to_str($b, 2), "]<br/>\n";
$c = bi_or($a, $b);
echo '$a or $b = [', bi_to_str($c, 2), "]<br/>\n";
$c = bi_xor($a, $b);
echo '$a xor $b = [', bi_to_str($c, 2), "]<br/>\n";
$c = bi_and($a, $b);
echo '$a and $b = [', bi_to_str($c, 2), "]<br/>\n";
$c = bi_andnot($a, $b);
echo '$a andnot $b = [', bi_to_str($c, 2), "]<br/>\n";
$c = bi_set_bit($a, 0);
echo 'set_bit($a, 0) = [', bi_to_str($c, 2), "]<br/>\n";
$c = bi_clr_bit($a, 0);
echo 'clr_bit($a, 0) = [', bi_to_str($c, 2), "]<br/>\n";
$c = bi_inv_bit($a, 0);
echo 'inv_bit($a, 0) = [', bi_to_str($c, 2), "]<br/>\n";
$c = bi_subint($a, 10, 20);
echo 'subint($a, 10, 20) = [', bi_to_str($c, 2), "]<br/>\n";
$c = bi_rshift($a, 10);
echo '$a >> 10 = [', bi_to_str($c, 2), "]<br/>\n";
$c = bi_lshift($a, 10);
echo '$a << 10 = [', bi_to_str($c, 2), "]<br/>\n";
echo '</div>', "<br/>\n";
echo 'Hamming distance($a, $b) = ', bi_hamming_distance($a, $b), "<br/>\n";
echo 'bit_len($a) = ', bi_bit_len($a), "<br/>\n";
echo 'bit1_cnt($a) = ', bi_bit1_cnt($a), "<br/>\n";
/**
returns a "good" prime $a with length $bit_len with
resrtiction:
$a - 1 != 0 (mod $e)
*/
function get_prime($bit_len)
{
return bi_next_prime(bi_set_bit(bi_rand($bit_len, 'microtime_generator'), $bit_len - 1));
}