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