Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:93275
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 209.85.213.180 as permitted sender)
MIME-Version: 1.0
Date: Thu, 12 May 2016 21:31:59 +0800
Message-ID: <CAHYcu1m=XGUp0LZscHcuVUHZGuW+XVs-XGTmDoebBO9wH8nvqQ@mail.gmail.com>
To: internals@lists.php.net
Content-Type: text/plain; charset=UTF-8
Subject: Request for RFC karma
From: sskaje@gmail.com (sskaje)

Hi,

I'm writing to request for RFC karma.

Here is what I am doing and why doing this.

The pack/unpack's parameter 'd' and 'f' are machine order in PHP.

The number 236.0 packed to 'd' is: 0000000000806d40.

I was reversing a game save file, which uses 406D800000000000.
Here is how I decode that in PHP.

        public function readDouble()
        {
                $data = substr($this->stream, $this->ptr, 8);
                $this->ptr += 8;

                $data = implode('', array_reverse(str_split($data, 1)));

                $int = unpack('d', $data);
                return (double) ($int[1]);
        }

Since integers are allowed to pack/unpack in both little endian and
big endian, I think double/float also need.

In this PR, I choose:
e: little endian double
E: big endian double
g: little endian float
G: big endian float.

BTW, these formats, 'e', 'E', 'g', and 'G' are not taken in Perl.


I've created a PR: https://github.com/php/php-src/pull/1905



sskaje
sskaje@gmail.com
https://sskaje.me/