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49 lines
1.6 KiB
C++
49 lines
1.6 KiB
C++
/*
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Copyright 2012 Wolfgang Thaller.
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This file is part of Retro68.
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Retro68 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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Retro68 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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You should have received a copy of the GNU General Public License
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along with Retro68. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "fixed.h"
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long fixed::nMul = 0, fixed::nIMul = 0, fixed::nDiv = 0, fixed::nSqrt = 0;
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fixed sqrt(fixed f)
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{
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COUNT_OP(fixed::nSqrt);
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const int FRACBITS = 16; /* Must be even! */
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const int ITERS = 15 + (FRACBITS >> 1);
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unsigned long root, remHi, remLo, testDiv, count;
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root = 0; /* Clear root */
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remHi = 0; /* Clear high part of partial remainder */
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remLo = f.val; /* Get argument into low part of partial remainder */
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count = ITERS; /* Load loop counter */
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do {
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remHi = (remHi << 2) | (remLo >> 30); remLo <<= 2; /* get 2 bits of arg */
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root <<= 1; /* Get ready for the next bit in the root */
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testDiv = (root << 1) + 1; /* Test radical */
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if (remHi >= testDiv) {
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remHi -= testDiv;
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root += 1;
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}
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} while (count-- != 0);
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return fixed(root, fixed::raw());
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}
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