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/* count-one-bits.h -- counts the number of 1-bits in a word.
Copyright (C) 2007-2021 Free Software Foundation, Inc.
This file 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 2.1 of the
License, or (at your option) any later version.
This file 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 <https://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
#ifdef __cplusplus
extern "C" {
#endif
/* Assuming the GCC builtin is GCC_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)) \
|| (__clang_major__ >= 4)
# define COUNT_ONE_BITS(GCC_BUILTIN, MSC_BUILTIN, TYPE) \
return GCC_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);
}
/* 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)
# 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. */
# if 0
# include <intrin.h>
# else
/* Don't pollute the namespace with too many MSVC intrinsics. */
# pragma intrinsic (__cpuid)
# pragma intrinsic (__popcnt)
# if defined _M_X64
# pragma intrinsic (__popcnt64)
# endif
# endif
# if !defined _M_X64
static inline __popcnt64 (unsigned long long x)
{
return __popcnt ((unsigned int) (x >> 32)) + __popcnt ((unsigned int) x);
}
# endif
/* 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)
{
/* Do as described in
<https://docs.microsoft.com/en-us/cpp/intrinsics/popcnt16-popcnt-popcnt64> */
int cpu_info[4];
__cpuid (cpu_info, 1);
popcount_support = (cpu_info[2] >> 23) & 1;
}
return popcount_support;
}
# define COUNT_ONE_BITS(GCC_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(GCC_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);
}
/* 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);
}
#ifdef __cplusplus
}
#endif
_GL_INLINE_HEADER_END
#endif /* COUNT_ONE_BITS_H */
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