mirror of
https://git.savannah.gnu.org/git/emacs.git
synced 2024-12-12 09:28:24 +00:00
137 lines
4.8 KiB
C
137 lines
4.8 KiB
C
/* count-one-bits.h -- counts the number of 1-bits in a word.
|
|
Copyright (C) 2007-2019 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 <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
|
|
|
|
/* 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 */
|