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To: internals@lists.php.net
References: <431C2738.2040602@wp.pl>
Date: Mon, 5 Sep 2005 16:02:21 +0200
Lines: 117
Subject: Re: crc32
From: r.korving@xit.nl ("Ron Korving")

Wouldn't it be more practical to implement these as stream filters?

Ron


"Wojtek Meler" <wmeler@wp.pl> schreef in bericht
news:431C2738.2040602@wp.pl...
> I've patched original crc32 PHP function to allow incremental crc32
> counting.
> It touches only a few lines of original code.
> New crc32 function signature is
>
>     int crc32(string str [,int prev_sum])
>
> With this patch you can generate crc32 checksum for even large files
> without reading it contents to single variable.
> Fe. instead of doing
>
> |   $file_string = file_get_contents($file);
>    $crc = crc32($file_string);
> |
> you can do
>
>     $crc=0;
>     $f =fopen($file,'r');
>     while ( $data=fread($f,1024)) $crc = crc32($data,$crc);
>     fclose($f);
>
> Icremental processing has less memory requirements.
> I'd like also change base64_* functions to allow incremental processing.
>
> Any chances apply such changes ?
>
> Regards,
> Wojtek
>


----------------------------------------------------------------------------
----


> Index: crc32.c
> ===================================================================
> RCS file: /repository/php-src/ext/standard/crc32.c,v
> retrieving revision 1.16
> diff -u -r1.16 crc32.c
> --- crc32.c 3 Aug 2005 14:07:57 -0000 1.16
> +++ crc32.c 5 Sep 2005 11:02:00 -0000
> @@ -1,13 +1,13 @@
>  /*
>
+----------------------------------------------------------------------+
> -   | PHP Version 5
|
> +   | PHP Version 4
|
>
+----------------------------------------------------------------------+
> -   | Copyright (c) 1997-2005 The PHP Group
|
> +   | Copyright (c) 1997-2003 The PHP Group
|
>
+----------------------------------------------------------------------+
> -   | This source file is subject to version 3.0 of the PHP license,
|
> +   | This source file is subject to version 2.02 of the PHP license,
|
>     | that is bundled with this package in the file LICENSE, and is
|
> -   | available through the world-wide-web at the following url:
|
> -   | http://www.php.net/license/3_0.txt.
|
> +   | available at through the world-wide-web at
|
> +   | http://www.php.net/license/2_02.txt.
|
>     | If you did not receive a copy of the PHP license and are unable to
|
>     | obtain it through the world-wide-web, please send a note to
|
>     | license@php.net so we can mail you a copy immediately.
|
> @@ -22,20 +22,19 @@
>  #include "basic_functions.h"
>  #include "crc32.h"
>
> -/* {{{ proto string crc32(string str)
> +/* {{{ proto int crc32(string str[,int prev_crc])
>     Calculate the crc32 polynomial of a string */
>  PHP_NAMED_FUNCTION(php_if_crc32)
>  {
> - unsigned int crc = ~0;
> + unsigned int crc = 0;
>   char *p;
> - int len, nr;
> + int len;
>
> - if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", &p, &nr) ==
FAILURE) {
> + if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s|l", &p, &len,
&crc) == FAILURE) {
>   return;
>   }
> -
> - len = 0 ;
> - for (len += nr; nr--; ++p) {
> + crc = ~crc;
> + for (; len--; ++p) {
>       CRC32(crc, *p);
>   }
>   RETVAL_LONG(~crc);
>