Fastest way to test quadword equality on SPU?

[kroe]

I may be overlooking something really obvios, but I can't find a good way to test equality of two quadwords.

I have two vector unsigned chars and I need to stop iterating when they are equal. The "==" comparator doesn't work with quadwords, and the spu_cmpeq intrinsic would require other subsequent operations to check the result of the equality test.

What is the best way to compare two quadwords for equality?

Thanks,
-Ken

[Mihawk]

If you're looking for a method without "other subsequent operations", then I believe there is none.

But this should be the shortest way I think:

Code: Select all

ceq	$5, $3, $4	# compare words
gb	$6, $5		# gather bits from words
ceqi	$7, $6, 15
# then branch or selb

or something like that (didn't test).

[emoon]

Maybe something like this (untested)

Code: Select all

inline bool spu_all_eq(vector unsigned int a, vector unsigned int b)
{
    return((spu_extract(spu_gather(spu_cmpeq(a, b)), 0) == 0xf));
}

[pheon]

or maybe

xor r1, r2, r3
orx r1, r1
brz / brnz

[Warren]

Maybe something like this (untested)

Code: Select all

inline bool spu_all_eq(vector unsigned int a, vector unsigned int b)
{
    return((spu_extract(spu_gather(spu_cmpeq(a, b)), 0) == 0xf));
}

spu_extract et al are somewhat slow routines and should be avoided if possible.

[unsolo]

result=spu_gather(spu_cmpeq(A,B)))

if any B is equal to A then you will have a value in the element 0 of result