/* $Id: bs3-cmn-SlabAlloc.c 62484 2016-07-22 18:35:33Z vboxsync $ */
/** @file
 * BS3Kit - Bs3SlabAlloc
 */

/*
 * Copyright (C) 2007-2016 Oracle Corporation
 *
 * This file is part of VirtualBox Open Source Edition (OSE), as
 * available from http://www.virtualbox.org. This file is free software;
 * you can redistribute it and/or modify it under the terms of the GNU
 * General Public License (GPL) as published by the Free Software
 * Foundation, in version 2 as it comes in the "COPYING" file of the
 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
 *
 * The contents of this file may alternatively be used under the terms
 * of the Common Development and Distribution License Version 1.0
 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
 * VirtualBox OSE distribution, in which case the provisions of the
 * CDDL are applicable instead of those of the GPL.
 *
 * You may elect to license modified versions of this file under the
 * terms and conditions of either the GPL or the CDDL or both.
 */


/*********************************************************************************************************************************
*   Header Files                                                                                                                 *
*********************************************************************************************************************************/
#include "bs3kit-template-header.h"
#include <iprt/asm.h>


#undef Bs3SlabAlloc
BS3_CMN_DEF(void BS3_FAR *, Bs3SlabAlloc,(PBS3SLABCTL pSlabCtl))
{
    if (pSlabCtl->cFreeChunks)
    {
        int32_t iBit = ASMBitFirstClear(&pSlabCtl->bmAllocated, pSlabCtl->cChunks);
        if (iBit >= 0)
        {
            BS3_XPTR_AUTO(void, pvRet);
            ASMBitSet(&pSlabCtl->bmAllocated, iBit);
            pSlabCtl->cFreeChunks  -= 1;

            BS3_XPTR_SET_FLAT(void, pvRet,
                              BS3_XPTR_GET_FLAT(uint8_t, pSlabCtl->pbStart) + ((uint32_t)iBit << pSlabCtl->cChunkShift));
            return BS3_XPTR_GET(void, pvRet);
        }
    }
    return NULL;
}