/* The Computer Language Shootout
http://shootout.alioth.debian.org/
contributed by Peter Baltruschat
*/
function primes($size)
{
$flags = array_fill(0, ($size >> 5) + 1, ~0);
$count = 0;
for ($i = 2; $i < $size; ++$i) {
$offset = $i >> 5;
$mask = 1 << $i - ($offset << 5);
if ($flags[$offset] & $mask) {
++$count;
for ($j = $i << 1; $j <= $size; $j += $i) {
$offset = $j >> 5;
$mask = 1 << $j - ($offset << 5);
if ($flags[$offset] & $mask) {
$flags[$offset] ^= $mask;
}
}
}
}
unset($flags);
printf("Primes up to %8d %8d\n", $size, $count);
}
$n = $argv[1] != '' ? $argv[1] : $_GET['n'];
$size = 10000 * (1 << $n);
primes($size);
primes($size >> 1);
primes($size >> 2);
/**
* @depends testPrimeLoader
* @expectedException \InvalidArgumentException
*/
public function testPrimesException()
{
primes('str');
}
/**
* Returns $nth prime number.
*
* @author Jitendra Adhikari <*****@*****.**>
*
* @uses self.primes()
* @param int The position in prime number series
*
* @return int The generated prime number
*
* @throws InvalidArgumentException If input is not positive integer
*/
function prime($n)
{
$primes = primes($n);
return end($primes);
}
*/
define(BPC, 32);
define(FLAG_MAX, 0xffffffff);
function primes($n)
{
$size = 10000 * pow(2, $n);
$flags = array();
$count = 0;
for ($i = 0; $i < $size / BPC + 1; $i++) {
$flags[$i] = FLAG_MAX;
}
for ($prime = 2; $prime < $size; $prime++) {
$offset = $prime / BPC;
$mask = pow(2, $prime % BPC);
if (($flags[$offset] & $mask) != 0) {
$count++;
for ($i = $prime * 2; $i <= $size; $i += $prime) {
$offset = $i / BPC;
$mask = pow(2, $i % BPC);
if (($flags[$offset] & $mask) != 0) {
$flags[$offset] ^= $mask;
}
}
}
}
printf("Primes up to %8d %8d\n", $size, $count);
}
$n = $argv[1] != '' ? $argv[1] : 1;
for ($i = 0; $i < 3; $i++) {
primes($n - $i);
}
