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/* $Id: bs3-cmn-SlabAllocEx.c $ */
/** @file
* BS3Kit - Bs3SlabAllocEx
*/
/*
* Copyright (C) 2007-2019 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 Bs3SlabAllocEx
BS3_CMN_DEF(void BS3_FAR *, Bs3SlabAllocEx,(PBS3SLABCTL pSlabCtl, uint16_t cChunks, uint16_t fFlags))
{
BS3_ASSERT(cChunks > 0);
if (pSlabCtl->cFreeChunks >= cChunks)
{
int32_t iBit = ASMBitFirstClear(&pSlabCtl->bmAllocated, pSlabCtl->cChunks);
if (iBit >= 0)
{
BS3_ASSERT(!ASMBitTest(&pSlabCtl->bmAllocated, iBit));
while ((uint32_t)iBit + cChunks <= pSlabCtl->cChunks)
{
/* Check that we've got the requested number of free chunks here. */
uint16_t i;
for (i = 1; i < cChunks; i++)
if (ASMBitTest(&pSlabCtl->bmAllocated, iBit + i))
break;
if (i == cChunks)
{
/* Check if the chunks are all in the same tiled segment. */
BS3_XPTR_AUTO(void, pvRet);
BS3_XPTR_SET_FLAT(void, pvRet,
BS3_XPTR_GET_FLAT(uint8_t, pSlabCtl->pbStart) + ((uint32_t)iBit << pSlabCtl->cChunkShift));
if ( !(fFlags & BS3_SLAB_ALLOC_F_SAME_TILE)
|| (BS3_XPTR_GET_FLAT(void, pvRet) >> 16)
== ((BS3_XPTR_GET_FLAT(void, pvRet) + ((uint32_t)cChunks << pSlabCtl->cChunkShift) - 1) >> 16) )
{
/* Complete the allocation. */
void *fpRet;
for (i = 0; i < cChunks; i++)
ASMBitSet(&pSlabCtl->bmAllocated, iBit + i);
pSlabCtl->cFreeChunks -= cChunks;
fpRet = BS3_XPTR_GET(void, pvRet);
#if ARCH_BITS == 16
BS3_ASSERT(fpRet != NULL);
#endif
return fpRet;
}
/*
* We're crossing a tiled segment boundrary.
* Skip to the start of the next segment and retry there.
* (We already know that the first chunk in the next tiled
* segment is free, otherwise we wouldn't have a crossing.)
*/
BS3_ASSERT(((uint32_t)cChunks << pSlabCtl->cChunkShift) <= _64K);
i = BS3_XPTR_GET_FLAT_LOW(void, pvRet);
i = UINT16_C(0) - i;
i >>= pSlabCtl->cChunkShift;
iBit += i;
}
else
{
/*
* Continue searching.
*/
iBit = ASMBitNextClear(&pSlabCtl->bmAllocated, pSlabCtl->cChunks, iBit + i);
if (iBit < 0)
break;
}
}
}
}
return NULL;
}
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