nuclear@0: /*
nuclear@0: ---------------------------------------------------------------------------
nuclear@0: Open Asset Import Library (assimp)
nuclear@0: ---------------------------------------------------------------------------
nuclear@0: 
nuclear@0: Copyright (c) 2006-2012, assimp team
nuclear@0: 
nuclear@0: All rights reserved.
nuclear@0: 
nuclear@0: Redistribution and use of this software in source and binary forms, 
nuclear@0: with or without modification, are permitted provided that the following 
nuclear@0: conditions are met:
nuclear@0: 
nuclear@0: * Redistributions of source code must retain the above
nuclear@0:   copyright notice, this list of conditions and the
nuclear@0:   following disclaimer.
nuclear@0: 
nuclear@0: * Redistributions in binary form must reproduce the above
nuclear@0:   copyright notice, this list of conditions and the
nuclear@0:   following disclaimer in the documentation and/or other
nuclear@0:   materials provided with the distribution.
nuclear@0: 
nuclear@0: * Neither the name of the assimp team, nor the names of its
nuclear@0:   contributors may be used to endorse or promote products
nuclear@0:   derived from this software without specific prior
nuclear@0:   written permission of the assimp team.
nuclear@0: 
nuclear@0: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
nuclear@0: "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
nuclear@0: LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
nuclear@0: A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
nuclear@0: OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
nuclear@0: SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
nuclear@0: LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
nuclear@0: DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 
nuclear@0: THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
nuclear@0: (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
nuclear@0: OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
nuclear@0: ---------------------------------------------------------------------------
nuclear@0: */
nuclear@0: 
nuclear@0: /**  @file  qnan.h
nuclear@0:  *   @brief Some utilities for our dealings with qnans.
nuclear@0:  *
nuclear@0:  *   @note Some loaders use qnans to mark invalid values tempoarily, also
nuclear@0:  *     Assimp explicitly enforces undefined normals to be set to qnan.
nuclear@0:  *     qnan utilities are available in standard libraries (C99 for example)
nuclear@0:  *     but last time I checked compiler coverage was so bad that I decided
nuclear@0:  *     to reinvent the wheel.
nuclear@0:  */
nuclear@0: 
nuclear@0: #ifndef AI_QNAN_H_INCLUDED
nuclear@0: #define AI_QNAN_H_INCLUDED
nuclear@0: 
nuclear@0: // ---------------------------------------------------------------------------
nuclear@0: /** Data structure to represent the bit pattern of a 32 Bit 
nuclear@0:  *         IEEE 754 floating-point number. */
nuclear@0: union _IEEESingle
nuclear@0: {
nuclear@0: 	float Float;
nuclear@0: 	struct
nuclear@0: 	{
nuclear@0: 		uint32_t Frac : 23;
nuclear@0: 		uint32_t Exp  : 8;
nuclear@0: 		uint32_t Sign : 1;
nuclear@0: 	} IEEE;
nuclear@0: } ;
nuclear@0: 
nuclear@0: // ---------------------------------------------------------------------------
nuclear@0: /** Check whether a given float is qNaN. 
nuclear@0:  *  @param in Input value */
nuclear@0: AI_FORCE_INLINE bool is_qnan(float in)	
nuclear@0: {
nuclear@0: 	// the straightforward solution does not work:
nuclear@0: 	//   return (in != in);
nuclear@0: 	// compiler generates code like this
nuclear@0: 	//   load <in> to <register-with-different-width>
nuclear@0: 	//   compare <register-with-different-width> against <in>
nuclear@0: 
nuclear@0: 	// FIXME: Use <float> stuff instead? I think fpclassify needs C99
nuclear@0: 	return (reinterpret_cast<_IEEESingle*>(&in)->IEEE.Exp == (1u << 8)-1 &&
nuclear@0: 		reinterpret_cast<_IEEESingle*>(&in)->IEEE.Frac);
nuclear@0: }
nuclear@0: 
nuclear@0: // ---------------------------------------------------------------------------
nuclear@0: /** Check whether a float is NOT qNaN. 
nuclear@0:  *  @param in Input value */
nuclear@0: AI_FORCE_INLINE bool is_not_qnan(float in)	
nuclear@0: {
nuclear@0: 	return !is_qnan(in);
nuclear@0: }
nuclear@0: 
nuclear@0: // ---------------------------------------------------------------------------
nuclear@0: /** @brief check whether a float is either NaN or (+/-) INF. 
nuclear@0:  *
nuclear@0:  *  Denorms return false, they're treated like normal values.
nuclear@0:  *  @param in Input value */
nuclear@0: AI_FORCE_INLINE bool is_special_float(float in)
nuclear@0: {
nuclear@0: 	return (reinterpret_cast<_IEEESingle*>(&in)->IEEE.Exp == (1u << 8)-1);
nuclear@0: }
nuclear@0: 
nuclear@0: // ---------------------------------------------------------------------------
nuclear@0: /** @brief Get a fresh qnan.  */
nuclear@0: AI_FORCE_INLINE float get_qnan()
nuclear@0: {
nuclear@0: 	return std::numeric_limits<float>::quiet_NaN();
nuclear@0: }
nuclear@0: 
nuclear@0: #endif // !! AI_QNAN_H_INCLUDED