From 49f178ed94b5fad00d25dbd12adea0bf4732f803 Mon Sep 17 00:00:00 2001 From: gatecat Date: Fri, 8 Apr 2022 13:42:54 +0100 Subject: Split up common into kernel,place,route Signed-off-by: gatecat --- common/kernel/bits.h | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 76 insertions(+) create mode 100644 common/kernel/bits.h (limited to 'common/kernel/bits.h') diff --git a/common/kernel/bits.h b/common/kernel/bits.h new file mode 100644 index 00000000..04b25b74 --- /dev/null +++ b/common/kernel/bits.h @@ -0,0 +1,76 @@ +/* + * 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 +#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 */ -- cgit v1.2.3