> On Tue, May 22, 2012 at 3:27 PM, Tatsuo Ishii <is...@postgresql.org> wrote:
> 
>> > Thanks for your comments. They clarify a lot.
>> > But I still don't realize how can we distinguish IS_LCPRV2 and IS_LC2?
>> > Isn't it possible for them to produce same pg_wchar?
>>
>> If LB is in 0x90 - 0x99 range, then they are LC2.
>> If LB is in 0xf0 - 0xff range, then they are LCPRV2.
>>
> 
> Thanks. I rewrote inverse conversion from pg_wchar to mule. New version of
> patch is attached.

[forgot to cc: to the list]

I looked into your patch, especially: pg_wchar2euc_with_len(const
pg_wchar *from, unsigned char *to, int len)

I think there's a small room to enhance the function.

                if (*from >> 24)
                {
                        *to++ = *from >> 24;
                        *to++ = (*from >> 16) & 0xFF;
                        *to++ = (*from >> 8) & 0xFF;
                        *to++ = *from & 0xFF;
                        cnt += 4;
                }

Since the function walk through this every single wchar, something like:

                if ((c = *from >> 24))
                {
                        *to++ = c;
                        *to++ = (*from >> 16) & 0xFF;
                        *to++ = (*from >> 8) & 0xFF;
                        *to++ = *from & 0xFF;
                        cnt += 4;
                }

will save few cycles(I'm not sure the optimizer produces similar code
above anyway though).
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

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