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src/util/rounding.h

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+/*
+ * 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.
+ */
+
+#ifndef _ROUNDING_H
+#define _ROUNDING_H
+
+#include <limits.h>
+#include <stdint.h>
+#include <math.h>
+
+#include "util/detect_arch.h"
+
+#if defined(__SSE__) || (defined(_M_IX86_FP) && (_M_IX86_FP >= 1)) || DETECT_ARCH_X86_64
+#include <xmmintrin.h>
+#include <emmintrin.h>
+#endif
+
+#ifdef __SSE4_1__
+#include <smmintrin.h>
+#endif
+
+/* 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)
+{
+#ifdef __SSE4_1__
+   float ret;
+   __m128 m = _mm_load_ss(&x);
+   m = _mm_round_ss(m, m, _MM_FROUND_CUR_DIRECTION | _MM_FROUND_NO_EXC);
+   _mm_store_ss(&ret, m);
+   return ret;
+#else
+   return rintf(x);
+#endif
+}
+
+/**
+ * \brief Rounds \c x to the nearest integer, with ties to the even integer.
+ */
+static inline double
+_mesa_roundeven(double x)
+{
+#ifdef __SSE4_1__
+   double ret;
+   __m128d m = _mm_load_sd(&x);
+   m = _mm_round_sd(m, m, _MM_FROUND_CUR_DIRECTION | _MM_FROUND_NO_EXC);
+   _mm_store_sd(&ret, m);
+   return ret;
+#else
+   return rint(x);
+#endif
+}
+
+/**
+ * \brief Rounds \c x to the nearest integer, with ties to the even integer,
+ * and returns the value as a long int.
+ */
+static inline long
+_mesa_lroundevenf(float x)
+{
+#if defined(__SSE__) || (defined(_M_IX86_FP) && (_M_IX86_FP >= 1)) || DETECT_ARCH_X86_64
+#if LONG_MAX == INT64_MAX
+   return _mm_cvtss_si64(_mm_load_ss(&x));
+#elif LONG_MAX == INT32_MAX
+   return _mm_cvtss_si32(_mm_load_ss(&x));
+#else
+#error "Unsupported long size"
+#endif
+#else
+   return lrintf(x);
+#endif
+}
+
+/**
+ * \brief Rounds \c x to the nearest integer, with ties to the even integer,
+ * and returns the value as a long int.
+ */
+static inline long
+_mesa_lroundeven(double x)
+{
+#if defined(__SSE2__) || (defined(_M_IX86_FP) && (_M_IX86_FP >= 2)) || DETECT_ARCH_X86_64
+#if LONG_MAX == INT64_MAX
+   return _mm_cvtsd_si64(_mm_load_sd(&x));
+#elif LONG_MAX == INT32_MAX
+   return _mm_cvtsd_si32(_mm_load_sd(&x));
+#else
+#error "Unsupported long size"
+#endif
+#else
+   return lrint(x);
+#endif
+}
+
+/**
+ * \brief Rounds \c x to the nearest integer, with ties to the even integer,
+ * and returns the value as an int64_t.
+ */
+static inline int64_t
+_mesa_i64roundevenf(float x)
+{
+#if LONG_MAX == INT64_MAX
+   return _mesa_lroundevenf(x);
+#elif LONG_MAX == INT32_MAX
+   return llrintf(x);
+#else
+#error "Unsupported long size"
+#endif
+}
+
+#endif