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/* mpn_popcount, mpn_hamdist -- mpn bit population count/hamming distance.
Copyright 1994, 1996, 2000-2002, 2005, 2011, 2012 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 either:
* 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.
or
* the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any
later version.
or both in parallel, as here.
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 General Public License
for more details.
You should have received copies of the GNU General Public License and the
GNU Lesser General Public License along with the GNU MP Library. If not,
see https://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
mp_bitcnt_t
FNAME (mp_srcptr up,
#if OPERATION_hamdist
mp_srcptr vp,
#endif
mp_size_t n) __GMP_NOTHROW
{
mp_bitcnt_t 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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