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Diffstat (limited to 'lib/count-one-bits.h')
| -rw-r--r-- | lib/count-one-bits.h | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/lib/count-one-bits.h b/lib/count-one-bits.h new file mode 100644 index 00000000000..2a7e93c3f40 --- /dev/null +++ b/lib/count-one-bits.h @@ -0,0 +1,136 @@ +/* count-one-bits.h -- counts the number of 1-bits in a word. + Copyright (C) 2007-2013 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU 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 General Public License for more details. + + You should have received a copy of the GNU 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 <limits.h> +#include <stdlib.h> + +#ifndef _GL_INLINE_HEADER_BEGIN + #error "Please include config.h first." +#endif +_GL_INLINE_HEADER_BEGIN +#ifndef COUNT_ONE_BITS_INLINE +# define COUNT_ONE_BITS_INLINE _GL_INLINE +#endif + +/* Expand to code that computes the number of 1-bits of the local + variable 'x' of type TYPE (an unsigned integer type) and return it + from the current function. */ +#define COUNT_ONE_BITS_GENERIC(TYPE) \ + do \ + { \ + int count = 0; \ + int bits; \ + for (bits = 0; bits < sizeof (TYPE) * CHAR_BIT; bits += 32) \ + { \ + count += count_one_bits_32 (x); \ + x = x >> 31 >> 1; \ + } \ + return count; \ + } \ + while (0) + +/* Assuming the GCC builtin is BUILTIN and the MSC builtin is MSC_BUILTIN, + expand to code that computes the number of 1-bits of the local + variable 'x' of type TYPE (an unsigned integer type) and return it + from the current function. */ +#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) +# define COUNT_ONE_BITS(BUILTIN, MSC_BUILTIN, TYPE) return BUILTIN (x) +#else + +/* Compute and return the number of 1-bits set in the least + significant 32 bits of X. */ +COUNT_ONE_BITS_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); +} + +# if 1500 <= _MSC_VER && (defined _M_IX86 || defined _M_X64) + +/* While gcc falls back to its own generic code if the machine + on which it's running doesn't support popcount, with Microsoft's + compiler we need to detect and fallback ourselves. */ +# pragma intrinsic __cpuid +# pragma intrinsic __popcnt +# pragma intrinsic __popcnt64 + +/* Return nonzero if popcount is supported. */ + +/* 1 if supported, 0 if not supported, -1 if unknown. */ +extern int popcount_support; + +COUNT_ONE_BITS_INLINE int +popcount_supported (void) +{ + if (popcount_support < 0) + { + int cpu_info[4]; + __cpuid (cpu_info, 1); + popcount_support = (cpu_info[2] >> 23) & 1; /* See MSDN. */ + } + return popcount_support; +} + +# define COUNT_ONE_BITS(BUILTIN, MSC_BUILTIN, TYPE) \ + do \ + { \ + if (popcount_supported ()) \ + return MSC_BUILTIN (x); \ + else \ + COUNT_ONE_BITS_GENERIC (TYPE); \ + } \ + while (0) +# else +# define COUNT_ONE_BITS(BUILTIN, MSC_BUILTIN, TYPE) \ + COUNT_ONE_BITS_GENERIC (TYPE) +# endif +#endif + +/* Compute and return the number of 1-bits set in X. */ +COUNT_ONE_BITS_INLINE int +count_one_bits (unsigned int x) +{ + COUNT_ONE_BITS (__builtin_popcount, __popcnt, unsigned int); +} + +/* Compute and return the number of 1-bits set in X. */ +COUNT_ONE_BITS_INLINE int +count_one_bits_l (unsigned long int x) +{ + COUNT_ONE_BITS (__builtin_popcountl, __popcnt, unsigned long int); +} + +#if HAVE_UNSIGNED_LONG_LONG_INT +/* Compute and return the number of 1-bits set in X. */ +COUNT_ONE_BITS_INLINE int +count_one_bits_ll (unsigned long long int x) +{ + COUNT_ONE_BITS (__builtin_popcountll, __popcnt64, unsigned long long int); +} +#endif + +_GL_INLINE_HEADER_END + +#endif /* COUNT_ONE_BITS_H */ |