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30 lines
807 B
C++
30 lines
807 B
C++
#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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