/*

  This program is part of the TACLeBench benchmark suite.
  Version V 1.x

  Name: bitcnt_4.c

  Author: Bob Stout

  Function: Recursive bit counting functions using table lookup

  Source: http://www.snippets.org/

  Changes: no major functional changes

  License: May be used, modified, and re-distributed freely.

*/


#include "bitops.h"   /* from Snippets */

static char bitcount_bits[ 256 ];

/*
**  Count bits in each nybble
**
**  Note: Only the first 16 table entries are used, the rest could be
**        omitted.
*/

void bitcount_init4( void )
{
  int volatile i = 0;
  char bitcount_bits_tmp[ 256 ] = {
    0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
  };

  for ( i = 0; i < 256; i++ )
    bitcount_bits[ i ] = bitcount_bits_tmp[ i ];
}

int bitcount_ntbl_bitcnt( unsigned long x )
{
    
  int cnt = bitcount_bits[ ( int )( x & 0x0000000FL ) ];

  if ( 0L != ( x >>= 4 ) )
    cnt += bitcount_ntbl_bitcnt( x );

  return cnt;
}

/*
**  Count bits in each byte
*/

int bitcount_btbl_bitcnt( unsigned long x )
{
#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
  int idx = sizeof(x) - 1;
#else
  int idx =  0;
#endif
  int cnt = bitcount_bits[( ( char * ) & x )[idx] & 0xFF];

  if ( 0L != ( x >>= 8 ) )
    cnt += bitcount_btbl_bitcnt( x );

  return cnt;
}