diff --git a/usrsctplib/user_atomic.h b/usrsctplib/user_atomic.h
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+/*-
+ * Copyright (c) 2009-2010 Brad Penoff
+ * Copyright (c) 2009-2010 Humaira Kamal
+ * Copyright (c) 2011-2012 Irene Ruengeler
+ * Copyright (c) 2011-2012 Michael Tuexen
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+ */
+
+#ifndef _USER_ATOMIC_H_
+#define _USER_ATOMIC_H_
+
+/* __Userspace__ version of sys/i386/include/atomic.h goes here */
+
+/* TODO In the future, might want to not use i386 specific assembly.
+ *    The options include:
+ *       - implement them generically (but maybe not truly atomic?) in userspace
+ *       - have ifdef's for __Userspace_arch_ perhaps (OS isn't enough...)
+ */
+
+#include <stdio.h>
+#include <sys/types.h>
+
+#if defined(__Userspace_os_Darwin) || defined (__Userspace_os_Windows)
+#if defined (__Userspace_os_Windows)
+#define atomic_add_int(addr, val) InterlockedExchangeAdd((LPLONG)addr, (LONG)val)
+#define atomic_fetchadd_int(addr, val) InterlockedExchangeAdd((LPLONG)addr, (LONG)val)
+#define atomic_subtract_int(addr, val)   InterlockedExchangeAdd((LPLONG)addr,-((LONG)val))
+#define atomic_cmpset_int(dst, exp, src) InterlockedCompareExchange((LPLONG)dst, src, exp)
+#define SCTP_DECREMENT_AND_CHECK_REFCOUNT(addr) (InterlockedExchangeAdd((LPLONG)addr, (-1L)) == 1)
+#else
+#include <libkern/OSAtomic.h>
+#define atomic_add_int(addr, val) OSAtomicAdd32Barrier(val, (int32_t *)addr)
+#define atomic_fetchadd_int(addr, val) OSAtomicAdd32Barrier(val, (int32_t *)addr)
+#define atomic_subtract_int(addr, val) OSAtomicAdd32Barrier(-val, (int32_t *)addr)
+#define atomic_cmpset_int(dst, exp, src) OSAtomicCompareAndSwapIntBarrier(exp, src, (int *)dst)
+#define SCTP_DECREMENT_AND_CHECK_REFCOUNT(addr) (atomic_fetchadd_int(addr, -1) == 0)
+#endif
+
+#if defined(INVARIANTS)
+#define SCTP_SAVE_ATOMIC_DECREMENT(addr, val) \
+{ \
+	int32_t newval; \
+	newval = atomic_fetchadd_int(addr, -val); \
+	if (newval < 0) { \
+		panic("Counter goes negative"); \
+	} \
+}
+#else
+#define SCTP_SAVE_ATOMIC_DECREMENT(addr, val) \
+{ \
+	int32_t newval; \
+	newval = atomic_fetchadd_int(addr, -val); \
+	if (newval < 0) { \
+		*addr = 0; \
+	} \
+}
+#endif
+#if defined(__Userspace_os_Windows)
+static void atomic_init() {} /* empty when we are not using atomic_mtx */
+#else
+static inline void atomic_init() {} /* empty when we are not using atomic_mtx */
+#endif
+
+#else
+/* Using gcc built-in functions for atomic memory operations
+   Reference: http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
+   Requires gcc version 4.1.0
+   compile with -march=i486
+ */
+
+/*Atomically add V to *P.*/
+#define atomic_add_int(P, V)	 (void) __sync_fetch_and_add(P, V)
+
+/*Atomically subtrace V from *P.*/
+#define atomic_subtract_int(P, V) (void) __sync_fetch_and_sub(P, V)
+
+/*
+ * Atomically add the value of v to the integer pointed to by p and return
+ * the previous value of *p.
+ */
+#define atomic_fetchadd_int(p, v) __sync_fetch_and_add(p, v)
+
+/* Following explanation from src/sys/i386/include/atomic.h,
+ * for atomic compare and set
+ *
+ * if (*dst == exp) *dst = src (all 32 bit words)
+ *
+ * Returns 0 on failure, non-zero on success
+ */
+
+#define atomic_cmpset_int(dst, exp, src) __sync_bool_compare_and_swap(dst, exp, src)
+
+#define SCTP_DECREMENT_AND_CHECK_REFCOUNT(addr) (atomic_fetchadd_int(addr, -1) == 1)
+#if defined(INVARIANTS)
+#define SCTP_SAVE_ATOMIC_DECREMENT(addr, val) \
+{ \
+	int32_t oldval; \
+	oldval = atomic_fetchadd_int(addr, -val); \
+	if (oldval < val) { \
+		panic("Counter goes negative"); \
+	} \
+}
+#else
+#define SCTP_SAVE_ATOMIC_DECREMENT(addr, val) \
+{ \
+	int32_t oldval; \
+	oldval = atomic_fetchadd_int(addr, -val); \
+	if (oldval < val) { \
+		*addr = 0; \
+	} \
+}
+#endif
+static inline void atomic_init() {} /* empty when we are not using atomic_mtx */
+#endif
+
+#if 0 /* using libatomic_ops */
+#include "user_include/atomic_ops.h"
+
+/*Atomically add incr to *P, and return the original value of *P.*/
+#define atomic_add_int(P, V)	 AO_fetch_and_add((AO_t*)P, V)
+
+#define atomic_subtract_int(P, V) AO_fetch_and_add((AO_t*)P, -(V))
+
+/*
+ * Atomically add the value of v to the integer pointed to by p and return
+ * the previous value of *p.
+ */
+#define atomic_fetchadd_int(p, v) AO_fetch_and_add((AO_t*)p, v)
+
+/* Atomically compare *addr to old_val, and replace *addr by new_val
+   if the first comparison succeeds.  Returns nonzero if the comparison
+   succeeded and *addr was updated.
+*/
+/* Following Explanation from src/sys/i386/include/atomic.h, which
+   matches that of AO_compare_and_swap above.
+ * Atomic compare and set, used by the mutex functions
+ *
+ * if (*dst == exp) *dst = src (all 32 bit words)
+ *
+ * Returns 0 on failure, non-zero on success
+ */
+
+#define atomic_cmpset_int(dst, exp, src) AO_compare_and_swap((AO_t*)dst, exp, src)
+
+static inline void atomic_init() {} /* empty when we are not using atomic_mtx */
+#endif /* closing #if for libatomic */
+
+#if 0 /* using atomic_mtx */
+
+#include <pthread.h>
+
+extern userland_mutex_t atomic_mtx;
+
+#if defined (__Userspace_os_Windows)
+static inline void atomic_init() {
+	InitializeCriticalSection(&atomic_mtx);
+}
+static inline void atomic_destroy() {
+	DeleteCriticalSection(&atomic_mtx);
+}
+static inline void atomic_lock() {
+	EnterCriticalSection(&atomic_mtx);
+}
+static inline void atomic_unlock() {
+	LeaveCriticalSection(&atomic_mtx);
+}
+#else
+static inline void atomic_init() {
+	pthread_mutexattr_t mutex_attr;
+
+	pthread_mutexattr_init(&mutex_attr);
+#ifdef INVARIANTS
+	pthread_mutexattr_settype(&mutex_attr, PTHREAD_MUTEX_ERRORCHECK);
+#endif
+	pthread_mutex_init(&accept_mtx, &mutex_attr);
+	pthread_mutexattr_destroy(&mutex_attr);
+}
+static inline void atomic_destroy() {
+	(void)pthread_mutex_destroy(&atomic_mtx);
+}
+static inline void atomic_lock() {
+#ifdef INVARIANTS
+	KASSERT(pthread_mutex_lock(&atomic_mtx) == 0, ("atomic_lock: atomic_mtx already locked"))
+#else
+	(void)pthread_mutex_lock(&atomic_mtx);
+#endif
+}
+static inline void atomic_unlock() {
+#ifdef INVARIANTS
+	KASSERT(pthread_mutex_unlock(&atomic_mtx) == 0, ("atomic_unlock: atomic_mtx not locked"))
+#else
+	(void)pthread_mutex_unlock(&atomic_mtx);
+#endif
+}
+#endif
+/*
+ * For userland, always use lock prefixes so that the binaries will run
+ * on both SMP and !SMP systems.
+ */
+
+#define	MPLOCKED	"lock ; "
+
+/*
+ * Atomically add the value of v to the integer pointed to by p and return
+ * the previous value of *p.
+ */
+static __inline u_int
+atomic_fetchadd_int(volatile void *n, u_int v)
+{
+	int *p = (int *) n;
+	atomic_lock();
+	__asm __volatile(
+	"	" MPLOCKED "		"
+	"	xaddl	%0, %1 ;	"
+	"# atomic_fetchadd_int"
+	: "+r" (v),			/* 0 (result) */
+	  "=m" (*p)			/* 1 */
+	: "m" (*p));			/* 2 */
+	atomic_unlock();
+
+	return (v);
+}
+
+
+#ifdef CPU_DISABLE_CMPXCHG
+
+static __inline int
+atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src)
+{
+	u_char res;
+
+	atomic_lock();
+	__asm __volatile(
+	"	pushfl ;		"
+	"	cli ;			"
+	"	cmpl	%3,%4 ;		"
+	"	jne	1f ;		"
+	"	movl	%2,%1 ;		"
+	"1:				"
+	"       sete	%0 ;		"
+	"	popfl ;			"
+	"# atomic_cmpset_int"
+	: "=q" (res),			/* 0 */
+	  "=m" (*dst)			/* 1 */
+	: "r" (src),			/* 2 */
+	  "r" (exp),			/* 3 */
+	  "m" (*dst)			/* 4 */
+	: "memory");
+	atomic_unlock();
+
+	return (res);
+}
+
+#else /* !CPU_DISABLE_CMPXCHG */
+
+static __inline int
+atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src)
+{
+	atomic_lock();
+	u_char res;
+
+	__asm __volatile(
+	"	" MPLOCKED "		"
+	"	cmpxchgl %2,%1 ;	"
+	"	sete	%0 ;		"
+	"1:				"
+	"# atomic_cmpset_int"
+	: "=a" (res),			/* 0 */
+	  "=m" (*dst)			/* 1 */
+	: "r" (src),			/* 2 */
+	  "a" (exp),			/* 3 */
+	  "m" (*dst)			/* 4 */
+	: "memory");
+	atomic_unlock();
+
+	return (res);
+}
+
+#endif /* CPU_DISABLE_CMPXCHG */
+
+#define atomic_add_int(P, V)	 do {   \
+		atomic_lock();          \
+		(*(u_int *)(P) += (V)); \
+		atomic_unlock();        \
+} while(0)
+#define atomic_subtract_int(P, V)  do {   \
+		atomic_lock();            \
+		(*(u_int *)(P) -= (V));   \
+		atomic_unlock();          \
+} while(0)
+
+#endif
+#endif