Ahah!
I believe I might have a possible hacky workaround!
Instead of doing:
static void mul(int[] accum, int accumOffset, int[] src, int srcOffset, int
n) {
for (int ii = 0; ii < n; ++ii) {
accum[ii + accumOffset] *= src[ii + srcOffset];
}
}
do
static void mul(int[] accum, int accumOffset, int[] src, int srcOffset, int
n) {
var diff = srcOffset - accumOffset;
rotate(accum, diff);
for (int ii = 0; ii < n; ++ii) {
accum[ii + accumOffset] *= src[ii + srcOffset];
}
rotate(accum, -diff);
}
where rotate rotates the array in place and so avoids expensive allocations
(and does the same amounts of copies as allocating temporaries would.)
I can see how rotating once can be done in place (and using
System.arraycopy so it could be fast.)
static void shiftOnce(int[] array) {
var len = array.length;
var start = array[0];
System.arraycopy(array, 0, array, 1, len - 1);
array[0] = start;
}
But I can't really see a good way of rotating an array in place for higher
counts (I doubt repeated iteration would be good.)
I'll still need to benchmark but this might be good.
--
You received this message because you are subscribed to the Google Groups
"mechanical-sympathy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/d/optout.
