116 lines
3.6 KiB
C
116 lines
3.6 KiB
C
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/*
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Berkeley Software Design, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)cdefs.h 8.8 (Berkeley) 1/9/95
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*/
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#ifndef _UTILS_H_
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#define _UTILS_H_
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#include <assert.h>
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/*
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* A regular assert (debug/diagnostic only).
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*/
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#if defined(DEBUG)
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#define ASSERT assert
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#else
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#define ASSERT(x)
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#endif
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/*
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* Minimum, maximum and rounding macros.
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*/
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#ifndef MIN
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#define MIN(x, y) ((x) < (y) ? (x) : (y))
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#endif
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#ifndef MAX
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#define MAX(x, y) ((x) > (y) ? (x) : (y))
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#endif
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/*
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* Branch prediction macros.
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*/
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#ifndef __predict_true
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#define __predict_true(x) __builtin_expect((x) != 0, 1)
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#define __predict_false(x) __builtin_expect((x) != 0, 0)
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#endif
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/*
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* Atomic operations and memory barriers. If C11 API is not available,
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* then wrap the GCC builtin routines.
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*
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* Note: This atomic_compare_exchange_weak does not do the C11 thing of
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* filling *(expected) with the actual value, because we don't need
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* that here.
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*/
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#ifndef atomic_compare_exchange_weak
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#define atomic_compare_exchange_weak(ptr, expected, desired) \
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__sync_bool_compare_and_swap(ptr, *(expected), desired)
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#endif
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#ifndef atomic_thread_fence
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#define memory_order_relaxed __ATOMIC_RELAXED
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#define memory_order_acquire __ATOMIC_ACQUIRE
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#define memory_order_release __ATOMIC_RELEASE
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#define memory_order_seq_cst __ATOMIC_SEQ_CST
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#define atomic_thread_fence(m) __atomic_thread_fence(m)
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#endif
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#ifndef atomic_store_explicit
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#define atomic_store_explicit __atomic_store_n
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#endif
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#ifndef atomic_load_explicit
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#define atomic_load_explicit __atomic_load_n
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#endif
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/*
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* Exponential back-off for the spinning paths.
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*/
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#define SPINLOCK_BACKOFF_MIN 4
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#define SPINLOCK_BACKOFF_MAX 128
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#if defined(__x86_64__) || defined(__i386__)
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#define SPINLOCK_BACKOFF_HOOK __asm volatile("pause" ::: "memory")
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#else
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#define SPINLOCK_BACKOFF_HOOK
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#endif
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#define SPINLOCK_BACKOFF(count) \
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do { \
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for (int __i = (count); __i != 0; __i--) { \
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SPINLOCK_BACKOFF_HOOK; \
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} \
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if ((count) < SPINLOCK_BACKOFF_MAX) \
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(count) += (count); \
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} while (/* CONSTCOND */ 0);
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#endif
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