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Use Gnulib's `count-one-bits' module.

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* m4/gnulib-cache.m4 (gl_MODULES): Add `count-one-bits'.
This commit is contained in:
Ludovic Courtès 2008-09-09 22:37:43 +02:00
parent 53f4876abc
commit d7014610b1
8 changed files with 293 additions and 2 deletions
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lib/count-one-bits.h Normal file
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/* count-one-bits.h -- counts the number of 1-bits in a word.
Copyright (C) 2007-2008 Free Software Foundation, Inc.
This program 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.
This program 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 this program. If not, see <http://www.gnu.org/licenses/>. */
/* Written by Ben Pfaff. */
#ifndef COUNT_ONE_BITS_H
# define COUNT_ONE_BITS_H 1
#include <stdlib.h>
#include "verify.h"
/* Expand the code which computes the number of 1-bits of the local
variable 'x' of type TYPE (an unsigned integer type) and returns it
from the current function. */
#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
#define COUNT_ONE_BITS(BUILTIN, TYPE) \
return BUILTIN (x);
#else
#define COUNT_ONE_BITS(BUILTIN, TYPE) \
/* This condition is written so as to avoid shifting by more than \
31 bits at once, and also avoids a random HP-UX cc bug. */ \
verify (((TYPE) -1 >> 31 >> 31 >> 2) == 0); /* TYPE has at most 64 bits */ \
int count = count_one_bits_32 (x); \
if (1 < (TYPE) -1 >> 31) /* TYPE has more than 32 bits? */ \
count += count_one_bits_32 (x >> 31 >> 1); \
return count;
/* Compute and return the the number of 1-bits set in the least
significant 32 bits of X. */
static inline int
count_one_bits_32 (unsigned int x)
{
x = ((x & 0xaaaaaaaaU) >> 1) + (x & 0x55555555U);
x = ((x & 0xccccccccU) >> 2) + (x & 0x33333333U);
x = (x >> 16) + (x & 0xffff);
x = ((x & 0xf0f0) >> 4) + (x & 0x0f0f);
return (x >> 8) + (x & 0x00ff);
}
#endif
/* Compute and return the number of 1-bits set in X. */
static inline int
count_one_bits (unsigned int x)
{
COUNT_ONE_BITS (__builtin_popcount, unsigned int);
}
/* Compute and return the number of 1-bits set in X. */
static inline int
count_one_bits_l (unsigned long int x)
{
COUNT_ONE_BITS (__builtin_popcountl, unsigned long int);
}
#if HAVE_UNSIGNED_LONG_LONG_INT
/* Compute and return the number of 1-bits set in X. */
static inline int
count_one_bits_ll (unsigned long long int x)
{
COUNT_ONE_BITS (__builtin_popcountll, unsigned long long int);
}
#endif
#endif /* COUNT_ONE_BITS_H */