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/******************************************************************************
* $Id$
*
* Project: CPL
* Purpose: Floating point conversion functions. Convert 16- and 24-bit
* floating point numbers into the 32-bit IEEE 754 compliant ones.
* Author: Andrey Kiselev, dron@remotesensing.org
*
******************************************************************************
* Copyright (c) 2005, Andrey Kiselev <dron@remotesensing.org>
*
* This code is based on the code from OpenEXR project with the following
* copyright:
*
* 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.
*
****************************************************************************/
#include "cpl_float.h"
#include "cpl_error.h"
/************************************************************************/
/* HalfToFloat() */
/* */
/* 16-bit floating point number to 32-bit one. */
/************************************************************************/
GUInt32 CPLHalfToFloat(GUInt16 iHalf)
{
GUInt32 iSign = (iHalf >> 15) & 0x00000001;
int iExponent = (iHalf >> 10) & 0x0000001f;
GUInt32 iMantissa = iHalf & 0x000003ff;
if (iExponent == 0)
{
if (iMantissa == 0)
{
/* --------------------------------------------------------------------
*/
/* Plus or minus zero. */
/* --------------------------------------------------------------------
*/
return iSign << 31;
}
else
{
/* --------------------------------------------------------------------
*/
/* Denormalized number -- renormalize it. */
/* --------------------------------------------------------------------
*/
while (!(iMantissa & 0x00000400))
{
iMantissa <<= 1;
iExponent -= 1;
}
iExponent += 1;
iMantissa &= ~0x00000400U;
}
}
else if (iExponent == 31)
{
if (iMantissa == 0)
{
/* --------------------------------------------------------------------
*/
/* Positive or negative infinity. */
/* --------------------------------------------------------------------
*/
return (iSign << 31) | 0x7f800000;
}
else
{
/* --------------------------------------------------------------------
*/
/* NaN -- preserve sign and significand bits. */
/* --------------------------------------------------------------------
*/
return (iSign << 31) | 0x7f800000 | (iMantissa << 13);
}
}
/* -------------------------------------------------------------------- */
/* Normalized number. */
/* -------------------------------------------------------------------- */
iExponent = iExponent + (127 - 15);
iMantissa = iMantissa << 13;
/* -------------------------------------------------------------------- */
/* Assemble sign, exponent and mantissa. */
/* -------------------------------------------------------------------- */
/* coverity[overflow_sink] */
return (iSign << 31) | (static_cast<GUInt32>(iExponent) << 23) | iMantissa;
}
/************************************************************************/
/* TripleToFloat() */
/* */
/* 24-bit floating point number to 32-bit one. */
/************************************************************************/
GUInt32 CPLTripleToFloat(GUInt32 iTriple)
{
GUInt32 iSign = (iTriple >> 23) & 0x00000001;
int iExponent = (iTriple >> 16) & 0x0000007f;
GUInt32 iMantissa = iTriple & 0x0000ffff;
if (iExponent == 0)
{
if (iMantissa == 0)
{
/* --------------------------------------------------------------------
*/
/* Plus or minus zero. */
/* --------------------------------------------------------------------
*/
return iSign << 31;
}
else
{
/* --------------------------------------------------------------------
*/
/* Denormalized number -- renormalize it. */
/* --------------------------------------------------------------------
*/
while (!(iMantissa & 0x00010000))
{
iMantissa <<= 1;
iExponent -= 1;
}
iExponent += 1;
iMantissa &= ~0x00010000U;
}
}
else if (iExponent == 127)
{
if (iMantissa == 0)
{
/* --------------------------------------------------------------------
*/
/* Positive or negative infinity. */
/* --------------------------------------------------------------------
*/
return (iSign << 31) | 0x7f800000;
}
else
{
/* --------------------------------------------------------------------
*/
/* NaN -- preserve sign and significand bits. */
/* --------------------------------------------------------------------
*/
return (iSign << 31) | 0x7f800000 | (iMantissa << 7);
}
}
/* -------------------------------------------------------------------- */
/* Normalized number. */
/* -------------------------------------------------------------------- */
iExponent = iExponent + (127 - 63);
iMantissa = iMantissa << 7;
/* -------------------------------------------------------------------- */
/* Assemble sign, exponent and mantissa. */
/* -------------------------------------------------------------------- */
/* coverity[overflow_sink] */
return (iSign << 31) | (static_cast<GUInt32>(iExponent) << 23) | iMantissa;
}
/************************************************************************/
/* FloatToHalf() */
/************************************************************************/
GUInt16 CPLFloatToHalf(GUInt32 iFloat32, bool &bHasWarned)
{
GUInt32 iSign = (iFloat32 >> 31) & 0x00000001;
GUInt32 iExponent = (iFloat32 >> 23) & 0x000000ff;
GUInt32 iMantissa = iFloat32 & 0x007fffff;
if (iExponent == 255)
{
if (iMantissa == 0)
{
/* --------------------------------------------------------------------
*/
/* Positive or negative infinity. */
/* --------------------------------------------------------------------
*/
return static_cast<GUInt16>((iSign << 15) | 0x7C00);
}
else
{
/* --------------------------------------------------------------------
*/
/* NaN -- preserve sign and significand bits. */
/* --------------------------------------------------------------------
*/
if (iMantissa >> 13)
return static_cast<GUInt16>((iSign << 15) | 0x7C00 |
(iMantissa >> 13));
return static_cast<GUInt16>((iSign << 15) | 0x7E00);
}
}
if (iExponent <= 127 - 15)
{
// Zero, float32 denormalized number or float32 too small normalized
// number
if (13 + 1 + 127 - 15 - iExponent >= 32)
return static_cast<GUInt16>(iSign << 15);
// Return a denormalized number
return static_cast<GUInt16>(
(iSign << 15) |
((iMantissa | 0x00800000) >> (13 + 1 + 127 - 15 - iExponent)));
}
if (iExponent - (127 - 15) >= 31)
{
if (!bHasWarned)
{
bHasWarned = true;
float fVal = 0.0f;
memcpy(&fVal, &iFloat32, 4);
CPLError(
CE_Failure, CPLE_AppDefined,
"Value %.8g is beyond range of float16. Converted to %sinf",
fVal, (fVal > 0) ? "+" : "-");
}
return static_cast<GUInt16>((iSign << 15) | 0x7C00); // Infinity
}
/* -------------------------------------------------------------------- */
/* Normalized number. */
/* -------------------------------------------------------------------- */
iExponent = iExponent - (127 - 15);
iMantissa = iMantissa >> 13;
/* -------------------------------------------------------------------- */
/* Assemble sign, exponent and mantissa. */
/* -------------------------------------------------------------------- */
// coverity[overflow_sink]
return static_cast<GUInt16>((iSign << 15) | (iExponent << 10) | iMantissa);
}
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