rounding.h revision 7ec681f3 
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(_M_IX86_FP) && (_M_IX86_FP >= 1)) || (defined(_M_X64) && !defined(_M_ARM64EC))
33#include <xmmintrin.h>
34#include <emmintrin.h>
35#endif
36
37#ifdef __SSE4_1__
38#include <smmintrin.h>
39#endif
40
41/* The C standard library has functions round()/rint()/nearbyint() that round
42 * their arguments according to the rounding mode set in the floating-point
43 * control register. While there are trunc()/ceil()/floor() functions that do
44 * a specific operation without modifying the rounding mode, there is no
45 * roundeven() in any version of C.
46 *
47 * Technical Specification 18661 (ISO/IEC TS 18661-1:2014) adds roundeven(),
48 * but it's unfortunately not implemented by glibc.
49 *
50 * This implementation differs in that it does not raise the inexact exception.
51 *
52 * We use rint() to implement these functions, with the assumption that the
53 * floating-point rounding mode has not been changed from the default Round
54 * to Nearest.
55 */
56
57/**
58 * \brief Rounds \c x to the nearest integer, with ties to the even integer.
59 */
60static inline float
61_mesa_roundevenf(float x)
62{
63#ifdef __SSE4_1__
64   float ret;
65   __m128 m = _mm_load_ss(&x);
66   m = _mm_round_ss(m, m, _MM_FROUND_CUR_DIRECTION | _MM_FROUND_NO_EXC);
67   _mm_store_ss(&ret, m);
68   return ret;
69#else
70   return rintf(x);
71#endif
72}
73
74/**
75 * \brief Rounds \c x to the nearest integer, with ties to the even integer.
76 */
77static inline double
78_mesa_roundeven(double x)
79{
80#ifdef __SSE4_1__
81   double ret;
82   __m128d m = _mm_load_sd(&x);
83   m = _mm_round_sd(m, m, _MM_FROUND_CUR_DIRECTION | _MM_FROUND_NO_EXC);
84   _mm_store_sd(&ret, m);
85   return ret;
86#else
87   return rint(x);
88#endif
89}
90
91/**
92 * \brief Rounds \c x to the nearest integer, with ties to the even integer,
93 * and returns the value as a long int.
94 */
95static inline long
96_mesa_lroundevenf(float x)
97{
98#if defined(__SSE__) || (defined(_M_IX86_FP) && (_M_IX86_FP >= 1)) || (defined(_M_X64) && !defined(_M_ARM64EC))
99#if LONG_MAX == INT64_MAX
100   return _mm_cvtss_si64(_mm_load_ss(&x));
101#elif LONG_MAX == INT32_MAX
102   return _mm_cvtss_si32(_mm_load_ss(&x));
103#else
104#error "Unsupported long size"
105#endif
106#else
107   return lrintf(x);
108#endif
109}
110
111/**
112 * \brief Rounds \c x to the nearest integer, with ties to the even integer,
113 * and returns the value as a long int.
114 */
115static inline long
116_mesa_lroundeven(double x)
117{
118#if defined(__SSE2__) || (defined(_M_IX86_FP) && (_M_IX86_FP >= 2)) || (defined(_M_X64) && !defined(_M_ARM64EC))
119#if LONG_MAX == INT64_MAX
120   return _mm_cvtsd_si64(_mm_load_sd(&x));
121#elif LONG_MAX == INT32_MAX
122   return _mm_cvtsd_si32(_mm_load_sd(&x));
123#else
124#error "Unsupported long size"
125#endif
126#else
127   return lrint(x);
128#endif
129}
130
131/**
132 * \brief Rounds \c x to the nearest integer, with ties to the even integer,
133 * and returns the value as an int64_t.
134 */
135static inline int64_t
136_mesa_i64roundevenf(float x)
137{
138#if LONG_MAX == INT64_MAX
139   return _mesa_lroundevenf(x);
140#elif LONG_MAX == INT32_MAX
141   return llrintf(x);
142#else
143#error "Unsupported long size"
144#endif
145}
146
147#endif
148