/src/FreeImage/Source/OpenEXR/IlmImf/ImfConvert.cpp

  1///////////////////////////////////////////////////////////////////////////
  2//
  3// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
  4// Digital Ltd. LLC
  5// 
  6// All rights reserved.
  7// 
  8// Redistribution and use in source and binary forms, with or without
  9// modification, are permitted provided that the following conditions are
 10// met:
 11// *       Redistributions of source code must retain the above copyright
 12// notice, this list of conditions and the following disclaimer.
 13// *       Redistributions in binary form must reproduce the above
 14// copyright notice, this list of conditions and the following disclaimer
 15// in the documentation and/or other materials provided with the
 16// distribution.
 17// *       Neither the name of Industrial Light & Magic nor the names of
 18// its contributors may be used to endorse or promote products derived
 19// from this software without specific prior written permission. 
 20// 
 21// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 22// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 23// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 24// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 25// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 32//
 33///////////////////////////////////////////////////////////////////////////
 34
 35
 36//-----------------------------------------------------------------------------
 37//
 38//	Routines for converting between pixel data types,
 39//	with well-defined behavior for exceptional cases.
 40//
 41//-----------------------------------------------------------------------------
 42
 43#include <ImfConvert.h>
 44#include <limits.h>
 45
 46namespace Imf {
 47namespace {
 48
 49inline bool
 50isNegative (float f)
 51{
 52    union {float f; int i;} u;
 53    u.f = f;
 54    return (u.i & 0x80000000) != 0;
 55}
 56
 57
 58inline bool
 59isNan (float f)
 60{
 61    union {float f; int i;} u;
 62    u.f = f;
 63    return (u.i & 0x7fffffff) > 0x7f800000;
 64}
 65
 66
 67inline bool
 68isInfinity (float f)
 69{
 70    union {float f; int i;} u;
 71    u.f = f;
 72    return (u.i & 0x7fffffff) == 0x7f800000;
 73}
 74
 75
 76inline bool
 77isFinite (float f)
 78{
 79    union {float f; int i;} u;
 80    u.f = f;
 81    return (u.i & 0x7f800000) != 0x7f800000;
 82}
 83
 84} // namespace
 85
 86
 87unsigned int
 88halfToUint (half h)
 89{
 90    if (h.isNegative() || h.isNan())
 91	return 0;
 92
 93    if (h.isInfinity())
 94	return UINT_MAX;
 95
 96    return (unsigned int) h;
 97}
 98
 99
100unsigned int
101floatToUint (float f)
102{
103    if (isNegative (f) || isNan (f))
104	return 0;
105
106    if (isInfinity (f) || f > UINT_MAX)
107	return UINT_MAX;
108
109    return (unsigned int) f;
110}
111
112
113half	
114uintToHalf (unsigned int ui)
115{
116    if (ui >  HALF_MAX)
117	return half::posInf();
118
119    return half (ui);
120}
121
122
123half	
124floatToHalf (float f)
125{
126    if (isFinite (f))
127    {
128	if (f >  HALF_MAX)
129	    return half::posInf();
130
131	if (f < -HALF_MAX)
132	    return half::negInf();
133    }
134
135    return half (f);
136}
137
138
139} // namespace Imf