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  1. #include <stdio.h>
  2.  
  3. int bit_count(int x)
  4. {
  5. 	int retVal;
  6.  
  7. 	int fives;
  8. 	fives = 0x55;
  9. 	fives |= fives << 0x08;
  10. 	fives |= fives << 0x10;
  11.  
  12. 	int threes;
  13. 	threes = 0x33;
  14. 	threes |= threes << 0x08;
  15. 	threes |= threes << 0x10;
  16.  
  17. 	int ofs;
  18. 	ofs = 0x0f;
  19. 	ofs |= ofs << 0x08;
  20. 	ofs |= ofs << 0x10;
  21.  
  22. 	int ooffs;
  23. 	ooffs = 0xff;
  24. 	ooffs |= ooffs << 0x10;
  25.  
  26. 	int ffff;
  27. 	ffff = 0xff;
  28. 	ffff |= ffff << 0x08;
  29.  
  30. 	retVal = x;
  31. 	retVal = ( retVal & fives ) + ( retVal >> 0x01 & fives );
  32. 	retVal = ( retVal & threes ) + ( retVal >> 0x02 & threes );
  33. 	retVal = ( retVal & ofs ) + ( retVal >> 0x04 & ofs );
  34. 	retVal = ( retVal & ooffs ) + ( retVal >> 0x08 & ooffs );
  35. 	retVal = ( retVal & ffff ) + ( retVal >> 0x10 & ffff );
  36.  
  37. 	return retVal;
  38. }
  39.  
  40. int main(void)
  41. {
  42. 	printf("%d\n", bit_count(0b11110000111100001111000011110000));
  43.  
  44. 	return 0;
  45. }
Success #stdin #stdout 0s 4392KB
comments (?)
stdin 
Standard input is empty
stdout 
16
https://ideone.com/nwUbVd
language:
C (gcc 8.3)
created:
8 years ago
visibility:
public

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