89 lines
2.4 KiB
C
89 lines
2.4 KiB
C
/* mpn_hamdist --
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Copyright (C) 1994, 1996 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Library General Public License as published by
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the Free Software Foundation; either version 2 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
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License for more details.
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You should have received a copy of the GNU Library General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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MA 02111-1307, USA. */
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#include "gmp.h"
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#include "gmp-impl.h"
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#if defined __GNUC__
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#if defined __sparc_v9__ && BITS_PER_MP_LIMB == 64
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#define popc_limb(a) \
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({ \
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DItype __res; \
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asm ("popc %1,%0" : "=r" (__res) : "rI" (a)); \
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__res; \
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})
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#endif
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#endif
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#ifndef popc_limb
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/* Cool population count of a mp_limb_t.
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You have to figure out how this works, I won't tell you! */
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static inline unsigned int
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popc_limb (x)
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mp_limb_t x;
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{
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#if BITS_PER_MP_LIMB == 64
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/* We have to go into some trouble to define these constants.
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(For mp_limb_t being `long long'.) */
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mp_limb_t cnst;
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cnst = 0x55555555L | ((mp_limb_t) 0x55555555L << BITS_PER_MP_LIMB/2);
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x = ((x & ~cnst) >> 1) + (x & cnst);
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cnst = 0x33333333L | ((mp_limb_t) 0x33333333L << BITS_PER_MP_LIMB/2);
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x = ((x & ~cnst) >> 2) + (x & cnst);
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cnst = 0x0f0f0f0fL | ((mp_limb_t) 0x0f0f0f0fL << BITS_PER_MP_LIMB/2);
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x = ((x >> 4) + x) & cnst;
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x = ((x >> 8) + x);
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x = ((x >> 16) + x);
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x = ((x >> 32) + x) & 0xff;
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#endif
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#if BITS_PER_MP_LIMB == 32
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x = ((x >> 1) & 0x55555555L) + (x & 0x55555555L);
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x = ((x >> 2) & 0x33333333L) + (x & 0x33333333L);
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x = ((x >> 4) + x) & 0x0f0f0f0fL;
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x = ((x >> 8) + x);
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x = ((x >> 16) + x) & 0xff;
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#endif
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return x;
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}
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#endif
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unsigned long int
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#if __STDC__
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mpn_hamdist (mp_srcptr up, mp_srcptr vp, mp_size_t size)
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#else
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mpn_hamdist (up, vp, size)
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register mp_srcptr up;
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register mp_srcptr vp;
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register mp_size_t size;
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#endif
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{
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unsigned long int hamdist;
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mp_size_t i;
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hamdist = 0;
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for (i = 0; i < size; i++)
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hamdist += popc_limb (up[i] ^ vp[i]);
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return hamdist;
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}
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