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41 lines
680 B
41 lines
680 B
/**
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* :author: Dan Buch (daniel.buch@gmail.com)
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*/
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#include <stdio.h>
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static unsigned int mask[] = {
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0x55555555,
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0x33333333,
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0x0F0F0F0F,
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0x00FF00FF,
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0x0000FFFF
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};
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int get_bit_count(unsigned int x)
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{
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int i;
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int shift; /* Number of positions to shift to right*/
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for (i = 0, shift = 1; i < 5; i++, shift *= 2) {
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x = (x & mask[i]) + ((x >> shift) & mask[i]);
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}
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return x;
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}
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int main()
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{
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int to_test[] = {0, 5, 7};
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int current;
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for (int i = 0; i < 3 ; i++) {
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current = to_test[i];
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printf("get_bit_count(%d) = %d\n", current, get_bit_count(current));
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}
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}
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/* vim:filetype=c:fileencoding=utf-8
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*/
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