<?php
function microtime_float() {
 list($usec, $sec) = explode(' ', microtime());
 return ((float)$usec + (float)$sec);
}
function file_crc($file) {
 $file_string = file_get_contents($file);
 $crc = crc32($file_string);
 return sprintf("%u", $crc);
}
function sfv_checksum($file) {
 $sfv_checksum = dechex(crc32(file_get_contents($file)));
 return $sfv_checksum;
}
function read_dir() {
$dir = '';
$i = 0;
if ($handle = opendir($dir)) {
 while (false !== ($file = readdir($handle))) {
  if ($file != "." && $file != "..") {
   $files[] = $dir.'/'.$file;
   $i++;
   if ($i >= 10000) return $files;
  }
 }
 closedir($handle);
}
 return $files;
}
$files = read_dir();
foreach($files as $file) {
$a = microtime_float();
$crc = crc32(implode(file($file)));
$b = microtime_float();
$crc2 = file_crc($file);
$c = microtime_float();
$md5 = md5_file($file);
$d = microtime_float();
$sha1 = sha1_file($file);
$e = microtime_float();
$sfv = sfv_checksum($file);
$f = microtime_float();
$times[0][] = ($b-$a);
$times[1][] = ($c-$b);
$times[2][] = ($d-$c);
$times[3][] = ($e-$d);
$times[4][] = ($f-$e);
}
echo 'crc32 takes'."\t".array_sum($times[0])."\n";
echo 'file_crc takes'."\t".array_sum($times[1])."\n";
echo 'md5 takes'."\t".array_sum($times[2])."\n";
echo 'sha1 takes'."\t".array_sum($times[3])."\n";
echo 'sfv takes'."\t".array_sum($times[4])."\n";
/*
OUTPUT
crc32 takes     29.046131134033
file_crc takes  7.7869794368744
md5 takes       7.2286281585693
sha1 takes      7.4805948734283
sfv takes       7.0564570426941
*/
?>