/*************************************************************************
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 * 
 * Copyright 2000, 2010 Oracle and/or its affiliates.
 *
 * OpenOffice.org - a multi-platform office productivity suite
 *
 * This file is part of OpenOffice.org.
 *
 * OpenOffice.org is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License version 3
 * only, as published by the Free Software Foundation.
 *
 * OpenOffice.org is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License version 3 for more details
 * (a copy is included in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU Lesser General Public License
 * version 3 along with OpenOffice.org.  If not, see
 * <http://www.openoffice.org/license.html>
 * for a copy of the LGPLv3 License.
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 ************************************************************************/

#include "system.h"

#include <osl/mutex.h>
#include <osl/diagnose.h>

/*
	Implementation notes:
	The void* hidden by oslMutex points to a WIN32
	CRITICAL_SECTION structure.
*/

typedef struct _oslMutexImpl {
	CRITICAL_SECTION	m_Mutex;
	int 				m_Locks;
	DWORD				m_Owner;
	DWORD				m_Requests;
} oslMutexImpl;

static BOOL (WINAPI *lpfTryEnterCriticalSection)(LPCRITICAL_SECTION)
	= (BOOL (WINAPI *)(LPCRITICAL_SECTION))0xFFFFFFFF;

static CRITICAL_SECTION MutexLock;

/*****************************************************************************/
/* osl_createMutex */
/*****************************************************************************/
oslMutex SAL_CALL osl_createMutex(void)
{
	oslMutexImpl *pMutexImpl;

	/* Window 95 does not support "TryEnterCriticalSection" */

	if (lpfTryEnterCriticalSection ==
				(BOOL (WINAPI *)(LPCRITICAL_SECTION))0xFFFFFFFF)
	{
		OSVERSIONINFO VersionInformation = 

		{
			sizeof(OSVERSIONINFO),
			0, 
	    	0, 
	    	0,
	    	0, 
	    	"",
		};

		/* ts: Window 98 does not support "TryEnterCriticalSection" but export the symbol !!!
		   calls to that symbol always returns FALSE */
		if (
			GetVersionEx(&VersionInformation) &&
			(VersionInformation.dwPlatformId == VER_PLATFORM_WIN32_NT)
		   )
		{
			lpfTryEnterCriticalSection = (BOOL (WINAPI *)(LPCRITICAL_SECTION))
					GetProcAddress(GetModuleHandle("KERNEL32"),
								   "TryEnterCriticalSection");
		}
		else
		{
			lpfTryEnterCriticalSection = (BOOL (WINAPI *)(LPCRITICAL_SECTION))NULL;
		}


		InitializeCriticalSection(&MutexLock);
	}

	pMutexImpl= calloc(sizeof(oslMutexImpl), 1);

	OSL_ASSERT(pMutexImpl); /* alloc successful? */

	InitializeCriticalSection(&pMutexImpl->m_Mutex);

	return (oslMutex)pMutexImpl;
}

/*****************************************************************************/
/* osl_destroyMutex */
/*****************************************************************************/
void SAL_CALL osl_destroyMutex(oslMutex Mutex)
{
	oslMutexImpl *pMutexImpl = (oslMutexImpl *)Mutex;

	if (pMutexImpl)
	{
		DeleteCriticalSection(&pMutexImpl->m_Mutex);
		free(pMutexImpl);
	}
}

/*****************************************************************************/
/* osl_acquireMutex */
/*****************************************************************************/
sal_Bool SAL_CALL osl_acquireMutex(oslMutex Mutex)
{
	oslMutexImpl *pMutexImpl = (oslMutexImpl *)Mutex;

	OSL_ASSERT(Mutex);

	if (lpfTryEnterCriticalSection == NULL)
	{
		EnterCriticalSection(&MutexLock);
		pMutexImpl->m_Requests++;
		LeaveCriticalSection(&MutexLock);

		EnterCriticalSection(&pMutexImpl->m_Mutex);

		EnterCriticalSection(&MutexLock);
		pMutexImpl->m_Requests--;
		if (pMutexImpl->m_Locks++ == 0)
			pMutexImpl->m_Owner = GetCurrentThreadId();
		LeaveCriticalSection(&MutexLock);
	}
	else
		EnterCriticalSection(&pMutexImpl->m_Mutex);

	return sal_True;
}

/*****************************************************************************/
/* osl_tryToAcquireMutex */
/*****************************************************************************/
sal_Bool SAL_CALL osl_tryToAcquireMutex(oslMutex Mutex)
{
	sal_Bool 	 ret = sal_False;
	oslMutexImpl *pMutexImpl = (oslMutexImpl *)Mutex;

	OSL_ASSERT(Mutex);

	if (lpfTryEnterCriticalSection != NULL)
		return (sal_Bool)(lpfTryEnterCriticalSection(&pMutexImpl->m_Mutex) != FALSE);
	else
	{
		EnterCriticalSection(&MutexLock);

		if ( ((pMutexImpl->m_Requests == 0) && (pMutexImpl->m_Locks == 0)) ||
			 (pMutexImpl->m_Owner == GetCurrentThreadId()) )
			ret = osl_acquireMutex(Mutex);

		LeaveCriticalSection(&MutexLock);
	}

	return ret;
}

/*****************************************************************************/
/* osl_releaseMutex */
/*****************************************************************************/
sal_Bool SAL_CALL osl_releaseMutex(oslMutex Mutex)
{
	oslMutexImpl *pMutexImpl = (oslMutexImpl *)Mutex;

	OSL_ASSERT(Mutex);

	if (lpfTryEnterCriticalSection == NULL)
	{
		EnterCriticalSection(&MutexLock);

		if (--(pMutexImpl->m_Locks) == 0)
			pMutexImpl->m_Owner = 0;

		LeaveCriticalSection(&MutexLock);
	}

	LeaveCriticalSection(&pMutexImpl->m_Mutex);

	return sal_True;
}

/*****************************************************************************/
/* osl_getGlobalMutex */
/*****************************************************************************/

/* initialized in dllentry.c */
oslMutex g_Mutex;

oslMutex * SAL_CALL osl_getGlobalMutex(void) 
{
	return &g_Mutex;
}