assimp/include/assimp/qnan.h

163 lines
5.5 KiB
C++

/*
---------------------------------------------------------------------------
Open Asset Import Library (assimp)
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All rights reserved.
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* Redistributions in binary form must reproduce the above
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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*/
/** @file qnan.h
* @brief Some utilities for our dealings with qnans.
*
* @note Some loaders use qnans to mark invalid values tempoarily, also
* Assimp explicitly enforces undefined normals to be set to qnan.
* qnan utilities are available in standard libraries (C99 for example)
* but last time I checked compiler coverage was so bad that I decided
* to reinvent the wheel.
*/
#pragma once
#ifndef AI_QNAN_H_INCLUDED
#define AI_QNAN_H_INCLUDED
#ifdef __GNUC__
# pragma GCC system_header
#endif
#include <assimp/defs.h>
#include <limits>
#include <stdint.h>
// ---------------------------------------------------------------------------
/** Data structure to represent the bit pattern of a 32 Bit
* IEEE 754 floating-point number. */
union _IEEESingle {
float Float;
struct
{
uint32_t Frac : 23;
uint32_t Exp : 8;
uint32_t Sign : 1;
} IEEE;
};
// ---------------------------------------------------------------------------
/** Data structure to represent the bit pattern of a 64 Bit
* IEEE 754 floating-point number. */
union _IEEEDouble {
double Double;
struct
{
uint64_t Frac : 52;
uint64_t Exp : 11;
uint64_t Sign : 1;
} IEEE;
};
// ---------------------------------------------------------------------------
/** Check whether a given float is qNaN.
* @param in Input value */
AI_FORCE_INLINE bool is_qnan(float in) {
// the straightforward solution does not work:
// return (in != in);
// compiler generates code like this
// load <in> to <register-with-different-width>
// compare <register-with-different-width> against <in>
// FIXME: Use <float> stuff instead? I think fpclassify needs C99
_IEEESingle temp;
memcpy(&temp, &in, sizeof(float));
return (temp.IEEE.Exp == (1u << 8)-1 &&
temp.IEEE.Frac);
}
// ---------------------------------------------------------------------------
/** Check whether a given double is qNaN.
* @param in Input value */
AI_FORCE_INLINE bool is_qnan(double in) {
// the straightforward solution does not work:
// return (in != in);
// compiler generates code like this
// load <in> to <register-with-different-width>
// compare <register-with-different-width> against <in>
// FIXME: Use <float> stuff instead? I think fpclassify needs C99
_IEEEDouble temp;
memcpy(&temp, &in, sizeof(in));
return (temp.IEEE.Exp == (1u << 11)-1 &&
temp.IEEE.Frac);
}
// ---------------------------------------------------------------------------
/** @brief check whether a float is either NaN or (+/-) INF.
*
* Denorms return false, they're treated like normal values.
* @param in Input value */
AI_FORCE_INLINE bool is_special_float(float in) {
_IEEESingle temp;
memcpy(&temp, &in, sizeof(float));
return (temp.IEEE.Exp == (1u << 8)-1);
}
// ---------------------------------------------------------------------------
/** @brief check whether a double is either NaN or (+/-) INF.
*
* Denorms return false, they're treated like normal values.
* @param in Input value */
AI_FORCE_INLINE bool is_special_float(double in) {
_IEEESingle temp;
memcpy(&temp, &in, sizeof(float));
return (temp.IEEE.Exp == (1u << 11)-1);
}
// ---------------------------------------------------------------------------
/** Check whether a float is NOT qNaN.
* @param in Input value */
template<class TReal>
AI_FORCE_INLINE bool is_not_qnan(TReal in) {
return !is_qnan(in);
}
// ---------------------------------------------------------------------------
/** @brief Get a fresh qnan. */
AI_FORCE_INLINE ai_real get_qnan() {
return std::numeric_limits<ai_real>::quiet_NaN();
}
#endif // !! AI_QNAN_H_INCLUDED