review request for 6798511/6860431: Include functionality of Surrogate in Character

[Ulf Zibis]

Very fast Sherman, much thanks.

Could you set the bug to accepted and evaluated, so my patch will have a 
chance to get into the code base?

-Ulf


Am 03.03.2010 20:11, schrieb Xueming Shen:
> #6931812
>
> Martin Buchholz wrote:
>> Sherman, would you like to file bugs for Ulf's improvements?
>>
>> On Wed, Mar 3, 2010 at 02:44, Ulf Zibis <Ulf.Zibis at gmx.de> wrote:
>>> Am 03.03.2010 09:00, schrieb Martin Buchholz:
>>
>>>> Keep in mind that supplementary characters are extremely rare.
>>>>
>>> Yes, but many API's in the JDK are used rarely.
>>> Why should they waste memory footprint / perform bad, particularly 
>>> if it
>>> doesn't cost anything.
>>
>> I admire your perfectionism.
>>
>>>> Therefore the existing implementation
>>>>
>>>>  return codePoint>= MIN_SUPPLEMENTARY_CODE_POINT
>>>> &&  codePoint<= MAX_CODE_POINT;
>>>>
>>>> will almost always perform just one comparison against a constant,
>>>> which is hard to beat.
>>>>
>>> 1. Wondering: I think there are TWO comparisons.
>>> 2. Those comparisons need to load 32 bit values from machine code, 
>>> against
>>> only 8 bit values in my case.
>>
>> It's a good point.  In the machine code, shifts are likely to use
>> immediate values, and so will be a small win.
>>
>> int x = codePoint >>> 16;
>> return x != 0 && x < 0x11;
>>
>> (On modern hardware, these optimizations
>> are less valuable than they used to be;
>> ordinary integer arithmetic is almost free)
>>
>> Martin
>
>