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/*
* Copyright (c) 2015-2017, Intel Corporation
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Intel Corporation nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/** \file
* \brief Platform specific popcount functions
*/
#ifndef UTIL_POPCOUNT_H_
#define UTIL_POPCOUNT_H_
#include "ue2common.h"
#include "util/arch.h"
static really_inline
u32 popcount32(u32 x) {
#if defined(HAVE_POPCOUNT_INSTR)
// Single-instruction builtin.
return _mm_popcnt_u32(x);
#else
// Fast branch-free version from bit-twiddling hacks as older Intel
// processors do not have a POPCNT instruction.
x -= (x >> 1) & 0x55555555;
x = (x & 0x33333333) + ((x >> 2) & 0x33333333);
return (((x + (x >> 4)) & 0xf0f0f0f) * 0x1010101) >> 24;
#endif
}
static really_inline
u32 popcount64(u64a x) {
#if defined(ARCH_X86_64)
# if defined(HAVE_POPCOUNT_INSTR)
// Single-instruction builtin.
return (u32)_mm_popcnt_u64(x);
# else
// Fast branch-free version from bit-twiddling hacks as older Intel
// processors do not have a POPCNT instruction.
x -= (x >> 1) & 0x5555555555555555;
x = (x & 0x3333333333333333) + ((x >> 2) & 0x3333333333333333);
x = (x + (x >> 4)) & 0x0f0f0f0f0f0f0f0f;
return (x * 0x0101010101010101) >> 56;
# endif
#else
// Synthesise from two 32-bit cases.
return popcount32(x >> 32) + popcount32(x);
#endif
}
#endif /* UTIL_POPCOUNT_H_ */
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