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Annotation of OpenXM_contrib/gmp/mpn/generic/hamdist.c, Revision 1.1

1.1     ! maekawa     1: /* mpn_hamdist --
        !             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_hamdist (mp_srcptr up, mp_srcptr vp, mp_size_t size)
        !            73: #else
        !            74: mpn_hamdist (up, vp, size)
        !            75:      register mp_srcptr up;
        !            76:      register mp_srcptr vp;
        !            77:      register mp_size_t size;
        !            78: #endif
        !            79: {
        !            80:   unsigned long int hamdist;
        !            81:   mp_size_t i;
        !            82:
        !            83:   hamdist = 0;
        !            84:   for (i = 0; i < size; i++)
        !            85:     hamdist += popc_limb (up[i] ^ vp[i]);
        !            86:
        !            87:   return hamdist;
        !            88: }