2 files changed, 59 insertions, 0 deletions
diff --git a/src/util/Makefile.sources b/src/util/Makefile.sources
index 560ea836aa1..3e0d02bad1e 100644
--- a/src/util/Makefile.sources
+++ b/src/util/Makefile.sources
@@ -14,6 +14,7 @@ MESA_UTIL_FILES :=	\
 	register_allocate.h \
 	rgtc.c \
 	rgtc.h \
+	rounding.h \
 	set.c \
 	set.h \
 	simple_list.h \
diff --git a/src/util/rounding.h b/src/util/rounding.h
new file mode 100644
index 00000000000..c8be45057b6
--- /dev/null
+++ b/src/util/rounding.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright © 2015 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <math.h>
+
+/* The C standard library has functions round()/rint()/nearbyint() that round
+ * their arguments according to the rounding mode set in the floating-point
+ * control register. While there are trunc()/ceil()/floor() functions that do
+ * a specific operation without modifying the rounding mode, there is no
+ * roundeven() in any version of C.
+ *
+ * Technical Specification 18661 (ISO/IEC TS 18661-1:2014) adds roundeven(),
+ * but it's unfortunately not implemented by glibc.
+ *
+ * This implementation differs in that it does not raise the inexact exception.
+ *
+ * We use rint() to implement these functions, with the assumption that the
+ * floating-point rounding mode has not been changed from the default Round
+ * to Nearest.
+ */
+
+/**
+ * \brief Rounds \c x to the nearest integer, with ties to the even integer.
+ */
+static inline float
+_mesa_roundevenf(float x)
+{
+   return rintf(x);
+}
+
+/**
+ * \brief Rounds \c x to the nearest integer, with ties to the even integer.
+ */
+static inline double
+_mesa_roundeven(double x)
+{
+   return rint(x);
+}