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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#include "common/lua/double_serialization.h"
#include "common/scummsys.h"
namespace Util {
SerializedDouble encodeDouble(double value) {
// Split the value into its significand and exponent
int exponent;
double significand = frexp(value, &exponent);
// Shift the the first part of the significand into the integer range
double shiftedsignificandPart = ldexp(fabs(significand), 32);
uint32 significandOne = uint32(floor(shiftedsignificandPart));
// Shift the remainder of the significand into the integer range
shiftedsignificandPart -= significandOne;
uint32 significandTwo = (uint32)(ldexp(shiftedsignificandPart, 31));
SerializedDouble returnValue;
returnValue.significandOne = significandOne; // SignificandOne
returnValue.signAndSignificandTwo = ((uint32)(value < 0 ? 1 : 0) << 31) | // Sign
significandTwo; // SignificandTwo
returnValue.exponent = (int16)exponent;
return returnValue;
}
double decodeDouble(SerializedDouble value) {
// Expand the exponent and the parts of the significand
int exponent = (int)value.exponent;
double expandedsignificandOne = (double)value.significandOne;
double expandedsignificandTwo = (double)(value.signAndSignificandTwo & 0x7FFFFFFF);
// Deflate the significand
double shiftedsignificand = ldexp(expandedsignificandTwo, -21);
double significand = ldexp(expandedsignificandOne + shiftedsignificand, -32);
// Re-calculate the actual double
double returnValue = ldexp(significand, exponent);
// Check the sign bit and return
return ((value.signAndSignificandTwo & 0x80000000) == 0x80000000) ? -returnValue : returnValue;
}
} // End of namespace Util
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