1/*
2---------------------------------------------------------------------------
3Open Asset Import Library (assimp)
4---------------------------------------------------------------------------
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6Copyright (c) 2006-2017, assimp team
7
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17 following disclaimer.
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41*/
42
43/** @file qnan.h
44 * @brief Some utilities for our dealings with qnans.
45 *
46 * @note Some loaders use qnans to mark invalid values tempoarily, also
47 * Assimp explicitly enforces undefined normals to be set to qnan.
48 * qnan utilities are available in standard libraries (C99 for example)
49 * but last time I checked compiler coverage was so bad that I decided
50 * to reinvent the wheel.
51 */
52
53#ifndef AI_QNAN_H_INCLUDED
54#define AI_QNAN_H_INCLUDED
55
56#include <assimp/defs.h>
57#include <limits>
58#include <stdint.h>
59
60// ---------------------------------------------------------------------------
61/** Data structure to represent the bit pattern of a 32 Bit
62 * IEEE 754 floating-point number. */
63union _IEEESingle
64{
65 float Float;
66 struct
67 {
68 uint32_t Frac : 23;
69 uint32_t Exp : 8;
70 uint32_t Sign : 1;
71 } IEEE;
72};
73
74// ---------------------------------------------------------------------------
75/** Data structure to represent the bit pattern of a 64 Bit
76 * IEEE 754 floating-point number. */
77union _IEEEDouble
78{
79 double Double;
80 struct
81 {
82 uint64_t Frac : 52;
83 uint64_t Exp : 11;
84 uint64_t Sign : 1;
85 } IEEE;
86};
87
88// ---------------------------------------------------------------------------
89/** Check whether a given float is qNaN.
90 * @param in Input value */
91AI_FORCE_INLINE bool is_qnan(float in)
92{
93 // the straightforward solution does not work:
94 // return (in != in);
95 // compiler generates code like this
96 // load <in> to <register-with-different-width>
97 // compare <register-with-different-width> against <in>
98
99 // FIXME: Use <float> stuff instead? I think fpclassify needs C99
100 return (reinterpret_cast<_IEEESingle*>(&in)->IEEE.Exp == (1u << 8)-1 &&
101 reinterpret_cast<_IEEESingle*>(&in)->IEEE.Frac);
102}
103
104// ---------------------------------------------------------------------------
105/** Check whether a given double is qNaN.
106 * @param in Input value */
107AI_FORCE_INLINE bool is_qnan(double in)
108{
109 // the straightforward solution does not work:
110 // return (in != in);
111 // compiler generates code like this
112 // load <in> to <register-with-different-width>
113 // compare <register-with-different-width> against <in>
114
115 // FIXME: Use <float> stuff instead? I think fpclassify needs C99
116 return (reinterpret_cast<_IEEEDouble*>(&in)->IEEE.Exp == (1u << 11)-1 &&
117 reinterpret_cast<_IEEEDouble*>(&in)->IEEE.Frac);
118}
119
120// ---------------------------------------------------------------------------
121/** @brief check whether a float is either NaN or (+/-) INF.
122 *
123 * Denorms return false, they're treated like normal values.
124 * @param in Input value */
125AI_FORCE_INLINE bool is_special_float(float in)
126{
127 return (reinterpret_cast<_IEEESingle*>(&in)->IEEE.Exp == (1u << 8)-1);
128}
129
130// ---------------------------------------------------------------------------
131/** @brief check whether a double is either NaN or (+/-) INF.
132 *
133 * Denorms return false, they're treated like normal values.
134 * @param in Input value */
135AI_FORCE_INLINE bool is_special_float(double in)
136{
137 return (reinterpret_cast<_IEEEDouble*>(&in)->IEEE.Exp == (1u << 11)-1);
138}
139
140// ---------------------------------------------------------------------------
141/** Check whether a float is NOT qNaN.
142 * @param in Input value */
143template<class TReal>
144AI_FORCE_INLINE bool is_not_qnan(TReal in)
145{
146 return !is_qnan(in);
147}
148
149// ---------------------------------------------------------------------------
150/** @brief Get a fresh qnan. */
151AI_FORCE_INLINE ai_real get_qnan()
152{
153 return std::numeric_limits<ai_real>::quiet_NaN();
154}
155
156#endif // !! AI_QNAN_H_INCLUDED
157