From 677f9aedbf78cf4acc3f4f26d8b48afd11590584 Mon Sep 17 00:00:00 2001
From: David M <davidmj@users.sourceforge.net>
Date: Thu, 9 Feb 2006 07:02:50 +0000
Subject: [PATCH] - It turns out that a very fast Adler-32 implementation
exists, this removes the bulk of my runtime fears and allows me to make the
script a little more readable. - Found a neat way to express the size of the
image computationally instead of counting the length - Removed pointless
iteration variables, they removed readability
git-svn-id: file:///svn/phpbb/trunk@5538 89ea8834-ac86-4346-8a33-228a782c2dd0
---
phpBB/includes/ucp/ucp_confirm.php | 65 ++++++++++++++++++------------
1 file changed, 40 insertions(+), 25 deletions(-)
diff --git a/phpBB/includes/ucp/ucp_confirm.php b/phpBB/includes/ucp/ucp_confirm.php
index 3bb1ff0a04..efbde293f0 100644
--- a/phpBB/includes/ucp/ucp_confirm.php
+++ b/phpBB/includes/ucp/ucp_confirm.php
@@ -40,18 +40,17 @@ class ucp_confirm
WHERE session_id = '" . $db->sql_escape($user->session_id) . "'
AND confirm_id = '" . $db->sql_escape($confirm_id) . "'";
$result = $db->sql_query($sql);
+ $row = $db->sql_fetchrow($result);
+ $db->sql_freeresult($result);
// If we have a row then grab data else create a new id
- if ($row = $db->sql_fetchrow($result))
- {
- $db->sql_freeresult($result);
- $code = $row['code'];
- }
- else
+ if (!$row)
{
exit;
}
+ $code = $row['code'];
+
// If we can we will generate a single filtered png, we avoid nastiness via emulation of some Zlib stuff
$_png = $this->define_filtered_pngs();
@@ -59,14 +58,13 @@ class ucp_confirm
$total_height = 50;
$img_height = 40;
$img_width = 0;
- $l = 0;
list($usec, $sec) = explode(' ', microtime());
mt_srand($sec * $usec);
$char_widths = array();
$code_len = strlen($code);
- for ($i = 0; $i < $code_len; ++$i)
+ for ($i = 0; $i < $code_len; $i++)
{
$char = $code{$i};
@@ -80,20 +78,18 @@ class ucp_confirm
$image = '';
$hold_chars = array();
- for ($i = 0; $i < $total_height; ++$i)
+ for ($i = 0; $i < $total_height; $i++)
{
$image .= chr(0);
if ($i > $offset_y && $i < $offset_y + $img_height)
{
- $j = 0;
-
- for ($k = 0; $k < $offset_x; ++$k)
+ for ($k = 0; $k < $offset_x; $k++)
{
$image .= chr(mt_rand(140, 255));
}
- for ($k = 0; $k < $code_len; ++$k)
+ for ($k = 0; $k < $code_len; $k++)
{
$char = $code{$k};
@@ -101,19 +97,17 @@ class ucp_confirm
{
$hold_chars[$char] = explode("\n", chunk_split(base64_decode($_png[$char]['data']), $_png[$char]['width'] + 1, "\n"));
}
- $image .= $this->randomise(substr($hold_chars[$char][$l], 1), $char_widths[$j++]);
+ $image .= $this->randomise(substr($hold_chars[$char][$i - $offset_y - 1], 1), $char_widths[$k]);
}
- for ($k = $offset_x + $img_width; $k < $total_width; ++$k)
+ for ($k = $offset_x + $img_width; $k < $total_width; $k++)
{
$image .= chr(mt_rand(140, 255));
}
-
- ++$l;
}
else
{
- for ($k = 0; $k < $total_width; ++$k)
+ for ($k = 0; $k < $total_width; $k++)
{
$image .= chr(mt_rand(140, 255));
}
@@ -142,7 +136,7 @@ class ucp_confirm
$new_line = '';
$end = strlen($scanline) - ceil($width/2);
- for ($i = floor($width/2); $i < $end; ++$i)
+ for ($i = floor($width/2); $i < $end; $i++)
{
$pixel = ord($scanline{$i});
@@ -196,18 +190,39 @@ class ucp_confirm
}
else
{
- $len = strlen($raw_image);
- // Adler-32 hash, lets go!
+ // The total length of this image, uncompressed, is just a calculation of pixels
+ $len = $temp_len = ($width + 1) * $height;
+
+ // Optimized Adler-32 loop ported from the GNU Classpath project
$s1 = 1;
$s2 = 0;
- for ($n = 0; $n < $len; ++$n) {
- $s1 = ($s1 + ord($raw_image[$n])) % 65521;
- $s2 = ($s2 + $s1) % 65521;
+ $i = 0;
+ while ($temp_len > 0)
+ {
+ // We can defer the modulo operation:
+ // s1 maximally grows from 65521 to 65521 + 255 * 3800
+ // s2 maximally grows by 3800 * median(s1) = 2090079800 < 2^31
+ $n = 3800;
+ if ($n > $temp_len)
+ {
+ $n = $temp_len;
+ }
+ $temp_len -= $n;
+ while (--$n >= 0)
+ {
+ $s1 += (ord($raw_image[$i++]) & 255);
+ $s2 += $s1;
+ }
+ $s1 %= 65521;
+ $s2 %= 65521;
}
$adler = ($s2 << 16) | $s1;
+
// This is the same thing as gzcompress($raw_image, 0)
- $raw_image = pack('C7', 0x78, 0x01, 1, $len & 255, ($len >> 8) & 255, 255 - ($len & 255), 255 - (($len >> 8) & 255)) . $raw_image;
+ $raw_image = pack('C7', 0x78, 0x01, 0x01, $len, ($len >> 8) & 255, ~$len & 255, ~($len >> 8)) . $raw_image;
$raw_image .= pack('C4', ($adler >> 24) & 255, ($adler >> 16) & 255, ($adler >> 8) & 255, $adler & 255);
+
+ // The Zlib header + Adler hash make us add on 11
$len += 11;
}
$image .= $this->png_chunk($len, 'IDAT', $raw_image);