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/*
* nextpnr -- Next Generation Place and Route
*
* Copyright (c) 2013 Mike Pedersen
* Copyright (C) 2021 Symbiflow Authors
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
// This is a small library for implementing common bit vector utilities,
// namely:
//
// - popcount : The number of bits set in an unsigned int
// - ctz : The number of trailing zero bits in an unsigned int.
// Must be called with a value that has at least 1 bit set.
//
// These methods will typically use instrinics when available, and have a
// generic fallback in the event that the instrinic is not available.
//
// If clz (count leading zeros) is needed, it can be added when needed.
#ifndef BITS_H
#define BITS_H
#if defined(_MSC_VER) && (defined(_M_X64) || defined(_M_IX86))
#include <intrin.h>
#pragma intrinsic(_BitScanForward, _BitScanReverse, __popcnt)
#endif
#include "nextpnr_namespaces.h"
NEXTPNR_NAMESPACE_BEGIN
struct Bits
{
static int generic_popcount(unsigned int x);
static int generic_ctz(unsigned int x);
static int popcount(unsigned int x)
{
#if defined(__GNUC__) || defined(__clang__)
return __builtin_popcount(x);
#elif defined(_MSC_VER) && (defined(_M_X64) || defined(_M_IX86))
return __popcnt(x);
#else
return generic_popcount(x);
#endif
}
static int ctz(unsigned int x)
{
#if defined(__GNUC__) || defined(__clang__)
return __builtin_ctz(x);
#elif defined(_MSC_VER) && (defined(_M_X64) || defined(_M_IX86))
unsigned long result;
_BitScanForward(&result, x);
return result;
#else
return generic_ctz(x);
#endif
}
};
NEXTPNR_NAMESPACE_END
#endif /* BITS_H */
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