parallel-rdp-standalone/util/bitops.hpp

106 lines
2.5 KiB
C++

/* Copyright (c) 2017-2020 Hans-Kristian Arntzen
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#pragma once
#ifdef _MSC_VER
#include <intrin.h>
#endif
namespace Util
{
#ifdef __GNUC__
#define leading_zeroes(x) ((x) == 0 ? 32 : __builtin_clz(x))
#define trailing_zeroes(x) ((x) == 0 ? 32 : __builtin_ctz(x))
#define trailing_ones(x) __builtin_ctz(~uint32_t(x))
#elif defined(_MSC_VER)
namespace Internal
{
static inline uint32_t clz(uint32_t x)
{
unsigned long result;
if (_BitScanReverse(&result, x))
return 31 - result;
else
return 32;
}
static inline uint32_t ctz(uint32_t x)
{
unsigned long result;
if (_BitScanForward(&result, x))
return result;
else
return 32;
}
}
#define leading_zeroes(x) ::Util::Internal::clz(x)
#define trailing_zeroes(x) ::Util::Internal::ctz(x)
#define trailing_ones(x) ::Util::Internal::ctz(~uint32_t(x))
#else
#error "Implement me."
#endif
template <typename T>
inline void for_each_bit(uint32_t value, const T &func)
{
while (value)
{
uint32_t bit = trailing_zeroes(value);
func(bit);
value &= ~(1u << bit);
}
}
template <typename T>
inline void for_each_bit_range(uint32_t value, const T &func)
{
if (value == ~0u)
{
func(0, 32);
return;
}
uint32_t bit_offset = 0;
while (value)
{
uint32_t bit = trailing_zeroes(value);
bit_offset += bit;
value >>= bit;
uint32_t range = trailing_ones(value);
func(bit_offset, range);
value &= ~((1u << range) - 1);
}
}
inline uint32_t next_pow2(uint32_t v)
{
v--;
v |= v >> 16;
v |= v >> 8;
v |= v >> 4;
v |= v >> 2;
v |= v >> 1;
return v + 1;
}
}