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https://github.com/libretro/scummvm.git
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68 lines
2.5 KiB
C++
68 lines
2.5 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "common/lua/double_serialization.h"
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#include "common/scummsys.h"
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namespace Util {
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SerializedDouble encodeDouble(double value) {
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// Split the value into its significand and exponent
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int exponent;
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double significand = frexp(value, &exponent);
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// Shift the first part of the significand into the integer range
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double shiftedsignificandPart = ldexp(fabs(significand), 32);
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uint32 significandOne = uint32(floor(shiftedsignificandPart));
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// Shift the remainder of the significand into the integer range
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shiftedsignificandPart -= significandOne;
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uint32 significandTwo = (uint32)(ldexp(shiftedsignificandPart, 31));
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SerializedDouble returnValue;
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returnValue.significandOne = significandOne; // SignificandOne
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returnValue.signAndSignificandTwo = ((uint32)(value < 0 ? 1 : 0) << 31) | // Sign
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significandTwo; // SignificandTwo
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returnValue.exponent = (int16)exponent;
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return returnValue;
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}
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double decodeDouble(SerializedDouble value) {
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// Expand the exponent and the parts of the significand
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int exponent = (int)value.exponent;
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double expandedsignificandOne = (double)value.significandOne;
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double expandedsignificandTwo = (double)(value.signAndSignificandTwo & 0x7FFFFFFF);
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// Deflate the significand
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double shiftedsignificand = ldexp(expandedsignificandTwo, -21);
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double significand = ldexp(expandedsignificandOne + shiftedsignificand, -32);
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// Re-calculate the actual double
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double returnValue = ldexp(significand, exponent);
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// Check the sign bit and return
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return ((value.signAndSignificandTwo & 0x80000000) == 0x80000000) ? -returnValue : returnValue;
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}
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} // End of namespace Util
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