mirror of
https://github.com/libretro/scummvm.git
synced 2025-01-07 10:21:31 +00:00
69 lines
2.6 KiB
C++
69 lines
2.6 KiB
C++
/* 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
|