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authorJosé Fonseca <[email protected]>2010-10-18 09:32:35 -0700
committerJosé Fonseca <[email protected]>2010-10-18 09:32:35 -0700
commitac17c62ecebf684eefcff65b9d58947a61ac361b (patch)
treefbba96d5ff680c9b9d643ad5b8dc59700f668899 /src/gallium
parent746b602fbdd6e7955e076c0c0d39e86b01bd3dfd (diff)
gallivm: Add a note about SSE4.1's nearest mode rounding.
Diffstat (limited to 'src/gallium')
-rw-r--r--src/gallium/auxiliary/gallivm/lp_bld_arit.c6
1 files changed, 6 insertions, 0 deletions
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,