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cs440-acg/ext/openexr/IlmBase/Half/halfFunction.h

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+///////////////////////////////////////////////////////////////////////////
+//
+// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
+// Digital Ltd. LLC
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+// *       Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// *       Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+// *       Neither the name of Industrial Light & Magic nor the names of
+// its contributors may be used to endorse or promote products derived
+// from this software without specific prior written permission. 
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+///////////////////////////////////////////////////////////////////////////
+
+// Primary authors:
+//     Florian Kainz <kainz@ilm.com>
+//     Rod Bogart <rgb@ilm.com>
+
+
+//---------------------------------------------------------------------------
+//
+//	halfFunction<T> -- a class for fast evaluation
+//			   of half --> T functions
+//
+//	The constructor for a halfFunction object,
+//
+//	    halfFunction (function,
+//			  domainMin, domainMax,
+//			  defaultValue,
+//			  posInfValue, negInfValue,
+//			  nanValue);
+//
+//	evaluates the function for all finite half values in the interval
+//	[domainMin, domainMax], and stores the results in a lookup table.
+//	For finite half values that are not in [domainMin, domainMax], the
+//	constructor stores defaultValue in the table.  For positive infinity,
+//	negative infinity and NANs, posInfValue, negInfValue and nanValue
+//	are stored in the table.
+//
+//	The tabulated function can then be evaluated quickly for arbitrary
+//	half values by calling the the halfFunction object's operator()
+//	method.
+//
+//	Example:
+//
+//	    #include <math.h>
+//	    #include <halfFunction.h>
+//
+//	    halfFunction<half> hsin (sin);
+//
+//	    halfFunction<half> hsqrt (sqrt,		// function
+//				      0, HALF_MAX,	// domain
+//				      half::qNan(),	// sqrt(x) for x < 0
+//				      half::posInf(),	// sqrt(+inf)
+//				      half::qNan(),	// sqrt(-inf)
+//				      half::qNan());	// sqrt(nan)
+//
+//	    half x = hsin (1);
+//	    half y = hsqrt (3.5);
+//
+//---------------------------------------------------------------------------
+
+#ifndef _HALF_FUNCTION_H_
+#define _HALF_FUNCTION_H_
+
+#include "half.h"
+
+#include "IlmBaseConfig.h"
+#ifndef ILMBASE_HAVE_LARGE_STACK  
+#include <string.h>     // need this for memset
+#else 
+#endif
+
+#include <float.h>
+
+
+template <class T>
+class halfFunction
+{
+  public:
+
+    //------------
+    // Constructor
+    //------------
+
+    template <class Function>
+    halfFunction (Function f,
+		  half domainMin = -HALF_MAX,
+		  half domainMax =  HALF_MAX,
+		  T defaultValue = 0,
+		  T posInfValue  = 0,
+		  T negInfValue  = 0,
+		  T nanValue     = 0);
+
+#ifndef ILMBASE_HAVE_LARGE_STACK
+    ~halfFunction () { delete [] _lut; }    
+#endif
+    
+    //-----------
+    // Evaluation
+    //-----------
+
+    T		operator () (half x) const;
+
+  private:
+
+#ifdef ILMBASE_HAVE_LARGE_STACK
+    T		_lut[1 << 16];
+#else
+    T *         _lut;
+#endif
+};
+
+
+//---------------
+// Implementation
+//---------------
+
+template <class T>
+template <class Function>
+halfFunction<T>::halfFunction (Function f,
+			       half domainMin,
+			       half domainMax,
+			       T defaultValue,
+			       T posInfValue,
+			       T negInfValue,
+			       T nanValue)
+{
+#ifndef ILMBASE_HAVE_LARGE_STACK
+    _lut = new T[1<<16];
+    memset (_lut, 0 , (1<<16) * sizeof(T));
+#endif
+    
+    for (int i = 0; i < (1 << 16); i++)
+    {
+	half x;
+	x.setBits (i);
+
+	if (x.isNan())
+	    _lut[i] = nanValue;
+	else if (x.isInfinity())
+	    _lut[i] = x.isNegative()? negInfValue: posInfValue;
+	else if (x < domainMin || x > domainMax)
+	    _lut[i] = defaultValue;
+	else
+	    _lut[i] = f (x);
+    }
+}
+
+
+template <class T>
+inline T
+halfFunction<T>::operator () (half x) const
+{
+    return _lut[x.bits()];
+}
+
+
+#endif