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author | Ludovic Courtès <ludo@gnu.org> | 2008-09-09 22:37:43 +0200 |
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committer | Ludovic Courtès <ludo@gnu.org> | 2008-09-09 22:37:43 +0200 |
commit | d7014610b16cd5f273479e70db253bff2f0124fc (patch) | |
tree | 37b11db3954a4883ce83318fa1eddee4fa3f4a01 /lib/count-one-bits.h | |
parent | 53f4876abcebf3f05d2a88bba3a898ddcda25a74 (diff) | |
download | guile-d7014610b16cd5f273479e70db253bff2f0124fc.tar.gz |
Use Gnulib's `count-one-bits' module.
* m4/gnulib-cache.m4 (gl_MODULES): Add `count-one-bits'.
Diffstat (limited to 'lib/count-one-bits.h')
-rw-r--r-- | lib/count-one-bits.h | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/lib/count-one-bits.h b/lib/count-one-bits.h new file mode 100644 index 000000000..7ecae84f0 --- /dev/null +++ b/lib/count-one-bits.h @@ -0,0 +1,77 @@ +/* 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 */ |