Req #53213 [Fbk->Opn]: Adler32 algorithm is very slow
Edit report at http://bugs.php.net/bug.php?id=53213&edit=1
ID: 53213
Updated by: aharvey@php.net
Reported by: zavasek at yandex dot ru
Summary: Adler32 algorithm is very slow
-Status: Feedback
+Status: Open
Type: Feature/Change Request
Package: hash related
Operating System: Any
PHP Version: 5.3.3
Block user comment: N
Previous Comments:
------------------------------------------------------------------------
[2010-10-31 20:45:28] pajoye@php.net
svn diff > mypatch.txt
and upload mypatch.txt here using the Add Patch link.
------------------------------------------------------------------------
[2010-10-31 20:40:47] zavasek at yandex dot ru
I've never used SVN and do not know how to create patches.
------------------------------------------------------------------------
[2010-10-31 19:14:48] pajoye@php.net
Can you provide a patch and attach it to this bug please ("Add a
patch")?
------------------------------------------------------------------------
[2010-10-31 18:22:17] zavasek at yandex dot ru
Description:
------------
Now adler32 algorithm for each byte uses two operations " % 65521". It
is very slow.
I propose to change the function PHP_ADLER32Update in the file
hash_adler32.c
{
php_hash_uint32 i, s[2];
s[0] = context->state & 0xffff;
s[1] = (context->state >> 16) & 0xffff;
for (i = 0; i < len; ++i) {
s[0] += input[i];
s[1] += s[0];
if (s[1]>0x7fffffff)
{
s[0] = s[0] % 65521;
s[1] = s[1] % 65521;
}
}
s[0] = s[0] % 65521;
s[1] = s[1] % 65521;
context->state = s[0] + (s[1] << 16);
}
Test script:
---------------
<?php
$t = microtime(true);
echo hash_file('adler32','/home/user/testfile')."\n"; // I used
testfile
size 400 MB with random content
echo sprintf('%0.3d',(microtime(true)-$t)*1000)." ms\n\n";
?>
Actual result:
--------------
PHP 5.3.3 showed:
85ffb2c5
2174 ms
After modification the file:
85ffb2c5
664 ms
Speed was higher than about 3 times
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/bug.php?id=53213&edit=1
Thread (6 messages)