60 lines
1.3 KiB
C++
60 lines
1.3 KiB
C++
/*
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* Copyright (C) OpenTX
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*
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* Based on code named
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* th9x - http://code.google.com/p/th9x
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* er9x - http://code.google.com/p/er9x
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* gruvin9x - http://code.google.com/p/gruvin9x
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*
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* License GPLv2: http://www.gnu.org/licenses/gpl-2.0.html
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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 version 2 as
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* published by the Free Software Foundation.
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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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#include "opentx.h"
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uint16_t isqrt32(uint32_t n)
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{
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uint16_t c = 0x8000;
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uint16_t g = 0x8000;
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for (;;) {
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if ((uint32_t)g*g > n)
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g ^= c;
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c >>= 1;
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if(c == 0)
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return g;
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g |= c;
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}
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}
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/*
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Division by 10 and rounding or fixed point arithmetic values
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Examples:
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value -> result
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105 -> 11
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104 -> 10
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-205 -> -21
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-204 -> -20
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*/
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// djb2 hash algorithm
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uint32_t hash(const void * ptr, uint32_t size)
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{
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const uint8_t * data = (const uint8_t *)ptr;
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uint32_t hash = 5381;
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for (uint32_t i=0; i<size; i++) {
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hash = ((hash << 5) + hash) + data[i]; /* hash * 33 + c */
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}
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return hash;
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}
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