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author | tege <tege@gmplib.org> | 1996-05-08 09:10:48 +0200 |
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committer | tege <tege@gmplib.org> | 1996-05-08 09:10:48 +0200 |
commit | c6d715868f53b08c62a129ffd77fb585fd89c43b (patch) | |
tree | 82f36d2d8cbe7e07ad3e18d5c6e047e8796d861e /mpn/generic/hamdist.c | |
download | gmp-c6d715868f53b08c62a129ffd77fb585fd89c43b.tar.gz |
Initial revision
Diffstat (limited to 'mpn/generic/hamdist.c')
-rw-r--r-- | mpn/generic/hamdist.c | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/mpn/generic/hamdist.c b/mpn/generic/hamdist.c new file mode 100644 index 000000000..2190b636f --- /dev/null +++ b/mpn/generic/hamdist.c @@ -0,0 +1,88 @@ +/* mpn_hamdist -- + +Copyright (C) 1994, 1996 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 Library General Public License as published by +the Free Software Foundation; either version 2 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 Library General Public +License for more details. + +You should have received a copy of the GNU Library 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 defined __GNUC__ +#if defined __sparc_v9__ && BITS_PER_MP_LIMB == 64 +#define popc_limb(a) \ + ({ \ + DItype __res; \ + asm ("popc %1,%0" : "=r" (__res) : "rI" (a)); \ + __res; \ + }) +#endif +#endif + +#ifndef popc_limb + +/* Cool population count of a mp_limb_t. + You have to figure out how this works, I won't tell you! */ + +static inline unsigned int +popc_limb (x) + mp_limb_t x; +{ +#if BITS_PER_MP_LIMB == 64 + /* We have to go into some trouble to define these constants. + (For mp_limb_t being `long long'.) */ + mp_limb_t cnst; + cnst = 0x55555555L | ((mp_limb_t) 0x55555555L << BITS_PER_MP_LIMB/2); + x = ((x & ~cnst) >> 1) + (x & cnst); + cnst = 0x33333333L | ((mp_limb_t) 0x33333333L << BITS_PER_MP_LIMB/2); + x = ((x & ~cnst) >> 2) + (x & cnst); + cnst = 0x0f0f0f0fL | ((mp_limb_t) 0x0f0f0f0fL << BITS_PER_MP_LIMB/2); + x = ((x >> 4) + x) & cnst; + x = ((x >> 8) + x); + x = ((x >> 16) + x); + x = ((x >> 32) + x) & 0xff; +#endif +#if BITS_PER_MP_LIMB == 32 + x = ((x >> 1) & 0x55555555L) + (x & 0x55555555L); + x = ((x >> 2) & 0x33333333L) + (x & 0x33333333L); + x = ((x >> 4) + x) & 0x0f0f0f0fL; + x = ((x >> 8) + x); + x = ((x >> 16) + x) & 0xff; +#endif + return x; +} +#endif + +unsigned long int +#if __STDC__ +mpn_hamdist (mp_srcptr up, mp_srcptr vp, mp_size_t size) +#else +mpn_hamdist (up, vp, size) + register mp_srcptr up; + register mp_srcptr vp; + register mp_size_t size; +#endif +{ + unsigned long int hamdist; + mp_size_t i; + + hamdist = 0; + for (i = 0; i < size; i++) + hamdist += popc_limb (up[i] ^ vp[i]); + + return hamdist; +} |