Ulf Zibis wrote:
Am 15.05.2009 00:03, Xueming Shen schrieb:
What is the "XOR approach"? I might have miss it. I'm happy to try it
out. OK, the "3 times computing" and "compare <0" are the good hint
to improve, the
latest one looks like
I'm afraid, you really missed it. See my post from 12.05.2009 20:25
CEST ;-)
I mean:
int cnsPlane = sa[sp +1] ^ 0xa0;
if (cnsPlane > 0xf || (cnsPlane = cnspToIndex[cnsPlane]) < 0)
return CoderResult.malformedForLength(2);
or maybe (to force LoadUB (Bug ID 6797305), which may be faster than
sign extension to int):
int cnsPlane = (sa[sp +1] ^ 0xa0) && 0xff;
or maybe use byte[] (to force LoadUB, which may be faster than sign
extension to int):
byte cnsPlane = (byte)(sa[sp +1] ^ 0xa0);
or
byte cnsPlane = (byte)((sa[sp +1] && 0xff) ^ (0xa0 &&
0xff)); // don't know if this make a difference
But anyway, I think,
static final byte[] cnspToIndex = new byte[0x100];
...
would be the fastest.
With the motivation of pushing you move on to the ibm charsets as quick
as possible:-) I've tried both xor and the
byte[256]. since we have to do "int cnsPlane = (sa[sp +1] ^ 0xa0) &&
0xff;", (without & 0xff, you got a negative
sign extension), it is not faster than the existing one, actually my
"not that accurate" benchmark shows it is slower...
The "static final byte[] cnspToIndex = new byte[0x100];" is slightly
faster, the measurement shows about 3-5%
improvement of the decoding. So the webrev has been updated to go with
this approach. Thanks!
Sherman
