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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 3 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. If not, see http://www.gnu.org/licenses/. */
#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 do 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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