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157c6af18e
Avoid cases of filenames Update years in terms and other legal(ish) documents Don't update years in license headers, since change is not meaningful Will add linter rule in seperate commit Happy recompiling everyone! Original Patch By: Nescio Comment By: Gallaecio Differential Revision: D2620 This was SVN commit r27786.
48 lines
1.4 KiB
C++
48 lines
1.4 KiB
C++
/* Copyright (C) 2010 Wildfire Games.
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* This file is part of 0 A.D.
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*
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* 0 A.D. 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 2 of the License, or
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* (at your option) any later version.
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*
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* 0 A.D. 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 0 A.D. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "precompiled.h"
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#include "Sqrt.h"
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// Based on http://freaknet.org/martin/tape/gos/misc/personal/msc/sqrt/sqrt.html
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u32 isqrt64(u64 n)
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{
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u64 op = n;
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u64 res = 0;
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u64 one = (u64)1 << 62; // highest power of four <= than the argument
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while (one > op)
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one >>= 2;
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while (one != 0)
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{
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if (op >= res + one)
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{
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op -= (res + one);
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res += (one << 1);
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}
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res >>= 1;
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one >>= 2;
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}
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return (u32)res;
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}
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// TODO: This should be equivalent to (u32)sqrt((double)n), and in practice
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// that seems to be true for all input, so do we actually need this integer-only
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// implementation? i.e. are there any platforms / compiler settings where
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// sqrt(double) won't give the correct answer? and is sqrt(double) faster?
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