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1 /*
2  * Copyright © 2015 Intel Corporation
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice (including the next
12  * paragraph) shall be included in all copies or substantial portions of the
13  * Software.
14  *
15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21  * IN THE SOFTWARE.
22  */
23 
24 #ifndef _ROUNDING_H
25 #define _ROUNDING_H
26 
27 #include "c99_math.h"
28 
29 #include <limits.h>
30 #include <stdint.h>
31 
32 #if defined(__SSE__) || defined(_MSC_VER)
33 /* MSVC always has SSE nowadays */
34 #include <xmmintrin.h>
35 #include <emmintrin.h>
36 #endif
37 
38 #ifdef __SSE4_1__
39 #include <smmintrin.h>
40 #endif
41 
42 /* The C standard library has functions round()/rint()/nearbyint() that round
43  * their arguments according to the rounding mode set in the floating-point
44  * control register. While there are trunc()/ceil()/floor() functions that do
45  * a specific operation without modifying the rounding mode, there is no
46  * roundeven() in any version of C.
47  *
48  * Technical Specification 18661 (ISO/IEC TS 18661-1:2014) adds roundeven(),
49  * but it's unfortunately not implemented by glibc.
50  *
51  * This implementation differs in that it does not raise the inexact exception.
52  *
53  * We use rint() to implement these functions, with the assumption that the
54  * floating-point rounding mode has not been changed from the default Round
55  * to Nearest.
56  */
57 
58 /**
59  * \brief Rounds \c x to the nearest integer, with ties to the even integer.
60  */
61 static inline float
_mesa_roundevenf(float x)62 _mesa_roundevenf(float x)
63 {
64 #ifdef __SSE4_1__
65    float ret;
66    __m128 m = _mm_load_ss(&x);
67    m = _mm_round_ss(m, m, _MM_FROUND_CUR_DIRECTION | _MM_FROUND_NO_EXC);
68    _mm_store_ss(&ret, m);
69    return ret;
70 #else
71    return rintf(x);
72 #endif
73 }
74 
75 /**
76  * \brief Rounds \c x to the nearest integer, with ties to the even integer.
77  */
78 static inline double
_mesa_roundeven(double x)79 _mesa_roundeven(double x)
80 {
81 #ifdef __SSE4_1__
82    double ret;
83    __m128d m = _mm_load_sd(&x);
84    m = _mm_round_sd(m, m, _MM_FROUND_CUR_DIRECTION | _MM_FROUND_NO_EXC);
85    _mm_store_sd(&ret, m);
86    return ret;
87 #else
88    return rint(x);
89 #endif
90 }
91 
92 /**
93  * \brief Rounds \c x to the nearest integer, with ties to the even integer,
94  * and returns the value as a long int.
95  */
96 static inline long
_mesa_lroundevenf(float x)97 _mesa_lroundevenf(float x)
98 {
99 #if defined(__SSE__) || defined(_MSC_VER)
100 #if LONG_MAX == INT64_MAX
101    return _mm_cvtss_si64(_mm_load_ss(&x));
102 #elif LONG_MAX == INT32_MAX
103    return _mm_cvtss_si32(_mm_load_ss(&x));
104 #else
105 #error "Unsupported long size"
106 #endif
107 #else
108    return lrintf(x);
109 #endif
110 }
111 
112 /**
113  * \brief Rounds \c x to the nearest integer, with ties to the even integer,
114  * and returns the value as a long int.
115  */
116 static inline long
_mesa_lroundeven(double x)117 _mesa_lroundeven(double x)
118 {
119 #if defined(__SSE__) || defined(_MSC_VER)
120 #if LONG_MAX == INT64_MAX
121    return _mm_cvtsd_si64(_mm_load_sd(&x));
122 #elif LONG_MAX == INT32_MAX
123    return _mm_cvtsd_si32(_mm_load_sd(&x));
124 #else
125 #error "Unsupported long size"
126 #endif
127 #else
128    return lrint(x);
129 #endif
130 }
131 
132 #endif
133