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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* GLOBAL FUNCTIONS:

** DESCRIPTION:

**     PR Atomic operations

*/

#ifndef pratom_h___

#define pratom_h___

#include "prtypes.h"

#include "prlock.h"

PR_BEGIN_EXTERN_C

/*

** FUNCTION: PR_AtomicIncrement

** DESCRIPTION:

**    Atomically increment a 32 bit value.

** INPUTS:

**    val:  a pointer to the value to increment

** RETURN:

**    the returned value is the result of the increment

*/

NSPR_API(PRInt32)   PR_AtomicIncrement(PRInt32 *val);

/*

** FUNCTION: PR_AtomicDecrement

** DESCRIPTION:

**    Atomically decrement a 32 bit value.

** INPUTS:

**    val:  a pointer to the value to decrement

** RETURN:

**    the returned value is the result of the decrement

*/

NSPR_API(PRInt32)   PR_AtomicDecrement(PRInt32 *val);

/*

** FUNCTION: PR_AtomicSet

** DESCRIPTION:

**    Atomically set a 32 bit value.

** INPUTS:

**    val: A pointer to a 32 bit value to be set

**    newval: The newvalue to assign to val

** RETURN:

**    Returns the prior value

*/

NSPR_API(PRInt32) PR_AtomicSet(PRInt32 *val, PRInt32 newval);

/*

** FUNCTION: PR_AtomicAdd

** DESCRIPTION:

**    Atomically add a 32 bit value.

** INPUTS:

**    ptr:  a pointer to the value to increment

**    val:  value to be added

** RETURN:

**    the returned value is the result of the addition

*/

NSPR_API(PRInt32)   PR_AtomicAdd(PRInt32 *ptr, PRInt32 val);

/*

** MACRO: PR_ATOMIC_INCREMENT

** MACRO: PR_ATOMIC_DECREMENT

** MACRO: PR_ATOMIC_SET

** MACRO: PR_ATOMIC_ADD

** DESCRIPTION:

**    Macro versions of the atomic operations.  They may be implemented

**    as compiler intrinsics.

**

** IMPORTANT NOTE TO NSPR MAINTAINERS:

**    Implement these macros with compiler intrinsics only on platforms

**    where the PR_AtomicXXX functions are truly atomic (i.e., where the

**    configuration macro _PR_HAVE_ATOMIC_OPS is defined).  Otherwise,

**    the macros and functions won't be compatible and can't be used

**    interchangeably.

*/

#if defined(_WIN32) && !defined(_WIN32_WCE) && \

    (!defined(_MSC_VER) || (_MSC_VER >= 1310))

#include <intrin.h>

#ifdef _MSC_VER

#pragma intrinsic(_InterlockedIncrement)

#pragma intrinsic(_InterlockedDecrement)

#pragma intrinsic(_InterlockedExchange)

#pragma intrinsic(_InterlockedExchangeAdd)

#endif

#define PR_ATOMIC_INCREMENT(val) _InterlockedIncrement((long volatile *)(val))

#define PR_ATOMIC_DECREMENT(val) _InterlockedDecrement((long volatile *)(val))

#define PR_ATOMIC_SET(val, newval) \

        _InterlockedExchange((long volatile *)(val), (long)(newval))

#define PR_ATOMIC_ADD(ptr, val) \

        (_InterlockedExchangeAdd((long volatile *)(ptr), (long)(val)) + (val))

#elif ((__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1)) && \

      ((defined(__APPLE__) && \

           (defined(__ppc__) || defined(__i386__) || defined(__x86_64__))) || \

       (defined(__linux__) && \

           ((defined(__i386__) && \

           defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)) || \

           defined(__ia64__) || defined(__x86_64__) || \

           defined(__powerpc__) || \

           (defined(__arm__) && \

           defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)) || \

           defined(__aarch64__) || defined(__alpha) || \

           (defined(__mips__) && \

           defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)))))

/*

 * Because the GCC manual warns that some processors may support

 * reduced functionality of __sync_lock_test_and_set, we test for the

 * processors that we believe support a full atomic exchange operation.

*/

#define PR_ATOMIC_INCREMENT(val) __sync_add_and_fetch(val, 1)

#define PR_ATOMIC_DECREMENT(val) __sync_sub_and_fetch(val, 1)

#define PR_ATOMIC_SET(val, newval) __sync_lock_test_and_set(val, newval)

#define PR_ATOMIC_ADD(ptr, val) __sync_add_and_fetch(ptr, val)

#else

#define PR_ATOMIC_INCREMENT(val) PR_AtomicIncrement(val)

#define PR_ATOMIC_DECREMENT(val) PR_AtomicDecrement(val)

#define PR_ATOMIC_SET(val, newval) PR_AtomicSet(val, newval)

#define PR_ATOMIC_ADD(ptr, val) PR_AtomicAdd(ptr, val)

#endif

/*

** LIFO linked-list (stack)

*/

typedef struct PRStackElemStr PRStackElem;

struct PRStackElemStr {

    PRStackElem *prstk_elem_next;   /* next pointer MUST be at offset 0;

                                      assembly language code relies on this */

};

typedef struct PRStackStr PRStack;

/*

** FUNCTION: PR_CreateStack

** DESCRIPTION:

**    Create a stack, a LIFO linked list

** INPUTS:

**    stack_name:  a pointer to string containing the name of the stack

** RETURN:

**    A pointer to the created stack, if successful, else NULL.

*/

NSPR_API(PRStack *) PR_CreateStack(const char *stack_name);

/*

** FUNCTION: PR_StackPush

** DESCRIPTION:

**    Push an element on the top of the stack

** INPUTS:

**    stack:        pointer to the stack

**    stack_elem:   pointer to the stack element

** RETURN:

**    None

*/

NSPR_API(void)          PR_StackPush(PRStack *stack, PRStackElem *stack_elem);

/*

** FUNCTION: PR_StackPop

** DESCRIPTION:

**    Remove the element on the top of the stack

** INPUTS:

**    stack:        pointer to the stack

** RETURN:

**    A pointer to the stack element removed from the top of the stack,

**    if non-empty,

**    else NULL

*/

NSPR_API(PRStackElem *) PR_StackPop(PRStack *stack);

/*

** FUNCTION: PR_DestroyStack

** DESCRIPTION:

**    Destroy the stack

** INPUTS:

**    stack:        pointer to the stack

** RETURN:

**    PR_SUCCESS - if successfully deleted

**    PR_FAILURE - if the stack is not empty

**                  PR_GetError will return

**                      PR_INVALID_STATE_ERROR - stack is not empty

*/

NSPR_API(PRStatus)      PR_DestroyStack(PRStack *stack);

PR_END_EXTERN_C

#endif /* pratom_h___ */