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/* mpn_popcount, mpn_hamdist -- mpn bit population count/hamming distance.
Copyright 1994, 1996, 2000, 2001, 2002, 2005 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.
The GNU MP Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the GNU MP Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include "gmp.h"
#include "gmp-impl.h"
#if OPERATION_popcount
#define FNAME mpn_popcount
#define POPHAM(u,v) u
#endif
#if OPERATION_hamdist
#define FNAME mpn_hamdist
#define POPHAM(u,v) u ^ v
#endif
unsigned long
FNAME (mp_srcptr up,
#if OPERATION_hamdist
mp_srcptr vp,
#endif
mp_size_t n)
{
unsigned long result = 0;
mp_limb_t p0, p1, p2, p3, x, p01, p23;
mp_size_t i;
ASSERT (n >= 1); /* Actually, this code handles any n, but some
assembly implementations does not. */
for (i = n >> 2; i != 0; i--)
{
p0 = POPHAM (up[0], vp[0]);
p0 -= (p0 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */
p0 = ((p0 >> 2) & MP_LIMB_T_MAX/5) + (p0 & MP_LIMB_T_MAX/5); /* 4 0-4 */
p1 = POPHAM (up[1], vp[1]);
p1 -= (p1 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */
p1 = ((p1 >> 2) & MP_LIMB_T_MAX/5) + (p1 & MP_LIMB_T_MAX/5); /* 4 0-4 */
p01 = p0 + p1; /* 8 0-8 */
p01 = ((p01 >> 4) & MP_LIMB_T_MAX/17) + (p01 & MP_LIMB_T_MAX/17); /* 8 0-16 */
p2 = POPHAM (up[2], vp[2]);
p2 -= (p2 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */
p2 = ((p2 >> 2) & MP_LIMB_T_MAX/5) + (p2 & MP_LIMB_T_MAX/5); /* 4 0-4 */
p3 = POPHAM (up[3], vp[3]);
p3 -= (p3 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */
p3 = ((p3 >> 2) & MP_LIMB_T_MAX/5) + (p3 & MP_LIMB_T_MAX/5); /* 4 0-4 */
p23 = p2 + p3; /* 8 0-8 */
p23 = ((p23 >> 4) & MP_LIMB_T_MAX/17) + (p23 & MP_LIMB_T_MAX/17); /* 8 0-16 */
x = p01 + p23; /* 8 0-32 */
x = (x >> 8) + x; /* 8 0-64 */
x = (x >> 16) + x; /* 8 0-128 */
#if GMP_LIMB_BITS > 32
x = ((x >> 32) & 0xff) + (x & 0xff); /* 8 0-256 */
result += x;
#else
result += x & 0xff;
#endif
up += 4;
#if OPERATION_hamdist
vp += 4;
#endif
}
n &= 3;
if (n != 0)
{
x = 0;
do
{
p0 = POPHAM (up[0], vp[0]);
p0 -= (p0 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */
p0 = ((p0 >> 2) & MP_LIMB_T_MAX/5) + (p0 & MP_LIMB_T_MAX/5); /* 4 0-4 */
p0 = ((p0 >> 4) + p0) & MP_LIMB_T_MAX/17; /* 8 0-8 */
x += p0;
up += 1;
#if OPERATION_hamdist
vp += 1;
#endif
}
while (--n);
x = (x >> 8) + x;
x = (x >> 16) + x;
#if GMP_LIMB_BITS > 32
x = (x >> 32) + x;
#endif
result += x & 0xff;
}
return result;
}
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