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https://github.com/esp8266/Arduino.git
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ce28a76a24
* +Esp.getHeapUnfragness() * only in debug mode * default value * always enable, 64->32, light 32 integer square root, comments * fix when debugging is disabled * give credits * cosmetics * fragmentation metric updates (doc, better api, added getMaxFreeBlockSize()) * api reworked, +example * fixe types, fix names * coding style fix * use astyle for example
57 lines
983 B
C
57 lines
983 B
C
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#include <coredecls.h>
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#include <stdint.h>
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uint32_t sqrt32 (uint32_t n)
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{
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// http://www.codecodex.com/wiki/Calculate_an_integer_square_root#C
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// Another very fast algorithm donated by Tristan.Muntsinger@gmail.com
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// (note: tested across the full 32 bits range, see comment below)
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// 15 iterations (c=1<<15)
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unsigned int c = 0x8000;
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unsigned int g = 0x8000;
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for(;;)
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{
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if (g*g > n)
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g ^= c;
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c >>= 1;
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if (!c)
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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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* tested with:
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*
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#include <stdio.h>
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#include <stdint.h>
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#include <math.h>
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int main (void)
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{
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for (uint32_t i = 0; ++i; )
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{
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uint32_t sr = sqrt32(i);
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uint32_t ifsr = sqrt(i);
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if (ifsr != sr)
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printf("%d: i%d f%d\n", i, sr, ifsr);
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if (!(i & 0xffffff))
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{
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printf("%i%% (0x%08x)\r", ((i >> 16) * 100) >> 16, i);
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fflush(stdout);
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}
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}
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printf("\n");
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}
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*
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*/
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