From ac17c62ecebf684eefcff65b9d58947a61ac361b Mon Sep 17 00:00:00 2001 From: José Fonseca Date: Mon, 18 Oct 2010 09:32:35 -0700 Subject: gallivm: Add a note about SSE4.1's nearest mode rounding. --- src/gallium/auxiliary/gallivm/lp_bld_arit.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'src/gallium') diff --git a/src/gallium/auxiliary/gallivm/lp_bld_arit.c b/src/gallium/auxiliary/gallivm/lp_bld_arit.c index 00f419a486d..f9a12a41a1b 100644 --- a/src/gallium/auxiliary/gallivm/lp_bld_arit.c +++ b/src/gallium/auxiliary/gallivm/lp_bld_arit.c @@ -983,6 +983,12 @@ enum lp_build_round_sse41_mode }; +/** + * Helper for SSE4.1's ROUNDxx instructions. + * + * NOTE: In the SSE4.1's nearest mode, if two values are equally close, the + * result is the even value. That is, rounding 2.5 will be 2.0, and not 3.0. + */ static INLINE LLVMValueRef lp_build_round_sse41(struct lp_build_context *bld, LLVMValueRef a, -- cgit v1.2.3