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Annotation of OpenXM_contrib/gmp/mpn/generic/popcount.c, Revision 1.1.1.1

1.1       maekawa     1: /* popcount.c
                      2:
                      3: Copyright (C) 1994, 1996 Free Software Foundation, Inc.
                      4:
                      5: This file is part of the GNU MP Library.
                      6:
                      7: The GNU MP Library is free software; you can redistribute it and/or modify
                      8: it under the terms of the GNU Library General Public License as published by
                      9: the Free Software Foundation; either version 2 of the License, or (at your
                     10: option) any later version.
                     11:
                     12: The GNU MP Library is distributed in the hope that it will be useful, but
                     13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
                     14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
                     15: License for more details.
                     16:
                     17: You should have received a copy of the GNU Library General Public License
                     18: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
                     19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
                     20: MA 02111-1307, USA. */
                     21:
                     22: #include "gmp.h"
                     23: #include "gmp-impl.h"
                     24:
                     25: #if defined __GNUC__
                     26: #if defined __sparc_v9__ && BITS_PER_MP_LIMB == 64
                     27: #define popc_limb(a) \
                     28:   ({                                                                   \
                     29:     DItype __res;                                                      \
                     30:     asm ("popc %1,%0" : "=r" (__res) : "rI" (a));                      \
                     31:     __res;                                                             \
                     32:   })
                     33: #endif
                     34: #endif
                     35:
                     36: #ifndef popc_limb
                     37:
                     38: /* Cool population count of a mp_limb_t.
                     39:    You have to figure out how this works, I won't tell you!  */
                     40:
                     41: static inline unsigned int
                     42: popc_limb (x)
                     43:      mp_limb_t x;
                     44: {
                     45: #if BITS_PER_MP_LIMB == 64
                     46:   /* We have to go into some trouble to define these constants.
                     47:      (For mp_limb_t being `long long'.)  */
                     48:   mp_limb_t cnst;
                     49:   cnst = 0x55555555L | ((mp_limb_t) 0x55555555L << BITS_PER_MP_LIMB/2);
                     50:   x = ((x & ~cnst) >> 1) + (x & cnst);
                     51:   cnst = 0x33333333L | ((mp_limb_t) 0x33333333L << BITS_PER_MP_LIMB/2);
                     52:   x = ((x & ~cnst) >> 2) + (x & cnst);
                     53:   cnst = 0x0f0f0f0fL | ((mp_limb_t) 0x0f0f0f0fL << BITS_PER_MP_LIMB/2);
                     54:   x = ((x >> 4) + x) & cnst;
                     55:   x = ((x >> 8) + x);
                     56:   x = ((x >> 16) + x);
                     57:   x = ((x >> 32) + x) & 0xff;
                     58: #endif
                     59: #if BITS_PER_MP_LIMB == 32
                     60:   x = ((x >> 1) & 0x55555555L) + (x & 0x55555555L);
                     61:   x = ((x >> 2) & 0x33333333L) + (x & 0x33333333L);
                     62:   x = ((x >> 4) + x) & 0x0f0f0f0fL;
                     63:   x = ((x >> 8) + x);
                     64:   x = ((x >> 16) + x) & 0xff;
                     65: #endif
                     66:   return x;
                     67: }
                     68: #endif
                     69:
                     70: unsigned long int
                     71: #if __STDC__
                     72: mpn_popcount (register mp_srcptr p, register mp_size_t size)
                     73: #else
                     74: mpn_popcount (p, size)
                     75:      register mp_srcptr p;
                     76:      register mp_size_t size;
                     77: #endif
                     78: {
                     79:   unsigned long int popcnt;
                     80:   mp_size_t i;
                     81:
                     82:   popcnt = 0;
                     83:   for (i = 0; i < size; i++)
                     84:     popcnt += popc_limb (p[i]);
                     85:
                     86:   return popcnt;
                     87: }