On 10/17/2014 08:58 PM, Staffan Friberg wrote:
Here is a new webrev with the updates from Alan's and Peter's
suggestions.
http://cr.openjdk.java.net/~sfriberg/JDK-6321472/webrev.01
Hi Staffan,
A few more comments...
217 if (Unsafe.ADDRESS_SIZE == 4) {
218 // On 32 bit platforms read two ints instead of a
single 64bit long
When you're reading from byte[] using Unsafe (updateBytes), you have the
option of reading 64bit values on 64bit platforms. When you're reading
from DirectByteBuffer memory (updateDirectByteBuffer), you're only using
32bit reads.
Also, in updateBytes, the usage of
Unsafe.ARRAY_INT_INDEX_SCALE/ARRAY_LONG_INDEX_SCALE to index a byte
array sounds a little scary. To be ultra portable you could check that
ARRAY_BYTE_INDEX_SCALE == 1 first and refuse to use Unsafe for byte
arrays if it is not 1. Then use Integer.BYTES/Long.BYTES to manipulate
'offsets' instead. In updateDirectByteBuffer it would be more
appropriate to use Integer.BYTES/Long.BYTES too.
225 firstHalf = (int) (value & 0xFFFFFFFF);
226 secondHalf = (int) (value >>> 32);
227 } else { // ByteOrder.BIG_ENDIAN
228 firstHalf = (int) (value >>> 32);
229 secondHalf = (int) (value & 0xFFFFFFFF);
firstHalf = (int) value; // this is equivalent for line 225
secondHalf = (int) value; // this is equivalent for line 229
Regards, Peter
