Req #53213 [Opn->Fbk]: Adler32 algorithm is very slow

Edit report at http://bugs.php.net/bug.php?id=53213&edit=1 ID: 53213 Updated by: pajoye@php.net Reported by: zavasek at yandex dot ru Summary: Adler32 algorithm is very slow -Status: Open +Status: Feedback Type: Feature/Change Request Package: hash related Operating System: Any PHP Version: 5.3.3 Block user comment: N New Comment: Can you provide a patch and attach it to this bug please ("Add a patch")? Previous Comments: ------------------------------------------------------------------------ [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