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zend_u_strtod is slow - possible fix

php.internals

Matt W

20 years ago

Hi all,

As I was working on upgrading the dec[bin|hex|oct] functions to convert
large doubles, I noticed how much slower things were when converting Unicode
strings to double.  I found that converting the whole thing to string and
using regular zend_strtod() was much faster.  Then I decided to try
modifying the u_strtod() function to do the same, but just on the relevant
numeric portion.

I don't know if I did everything right, but it seems to work fine with my
limited testing.  (I was working from zend_u_strtol() and
zval_unicode_to_string_ex(). :-))  The function is now about *8 times*
faster, and nearly 20 times faster on a non-numeric string!  (I'm on
Windows.)

diff: http://realplain.com/php/zend_u_strtod.diff

Is this something that can be used?


Thanks,
Matt

Andrei Zmievski

20 years ago

Yes. With your patch applied, the numeric unicode string to double
conversion is about 100% slower than from binary strings. If this is
acceptable we can commit the patch. Otherwise, we should port
zend_strtod() to deal with unicode strings directly.

-Andrei

On Jul 31, 2006, at 1:58 AM, Matt W wrote:

Matt W

20 years ago

Hi Andrei,

Thanks for your reply.  Yeah, obviously it'll still be slower than with an
already-binary string. :-)  But I figured it's better than before, until
something better comes along...

Unless there were other plans to rewrite it, is there a way to easily (for
me! :-)) have it do all the conversion?  I've been thinking about the
different string-to-number functions (will send a separate e-mail)...  Is
there a reason the regular zend_strtod() code is so complicated?
zend_string_to_double(), for example, is really simple (and works the same I
assume, except for not handling negatives or leading whitespace).  Can
zend_u_strtod() be implemented with the same methods zend_string_to_double()
uses?


Thanks,
Matt


----- Original Message -----
From: "Andrei Zmievski"
Sent: Tuesday, August 01, 2006

Andrei Zmievski

20 years ago

You'd have to ask Derick. He's the one who added it. :) Note that
zend_string_to_double() is not actually used anywhere.

-A

On Aug 2, 2006, at 2:12 AM, Matt W wrote:

Derick Rethans

20 years ago

On Wed, 2 Aug 2006, Andrei Zmievski wrote:

> You'd have to ask Derick. He's the one who added it. :) Note that
> zend_string_to_double() is not actually used anywhere.

I stole it from BSD, and yes... this is really needed because of all the
different architectures.

Derick

Andrei Zmievski

20 years ago

Want to port it to support UChar*?

-A

On Aug 3, 2006, at 12:24 AM, Derick Rethans wrote: